<section xml:id="dns_overview"><info><title>The Domain Name System (<acronym>DNS</acronym>)</title></info>
<para>
- The purpose of this document is to explain the installation
+ This document explains the installation
and upkeep of the <acronym>BIND</acronym> (Berkeley Internet
- Name Domain) software package, and we
+ Name Domain) software package. We
begin by reviewing the fundamentals of the Domain Name System
(<acronym>DNS</acronym>) as they relate to <acronym>BIND</acronym>.
</para>
<para>
For administrative purposes, the name space is partitioned into
areas called <emphasis>zones</emphasis>, each starting at a node and
- extending down to the leaf nodes or to nodes where other zones
+ extending down to the "leaf" nodes or to nodes where other zones
start.
The data for each zone is stored in a <emphasis>name server</emphasis>, which answers queries about the zone using the
<emphasis>DNS protocol</emphasis>.
<emphasis>terminal</emphasis>, that is, has no
<emphasis>subdomains</emphasis>. Every subdomain is a domain and
every domain except the root is also a subdomain. The terminology is
- not intuitive and we suggest that you read RFCs 1033, 1034 and 1035
+ not intuitive and we suggest reading RFCs 1033, 1034, and 1035
to
gain a complete understanding of this difficult and subtle
topic.
<para>
Though <acronym>BIND</acronym> is called a "domain name
server",
- it deals primarily in terms of zones. The master and slave
+ it deals primarily in terms of zones. The "primary" and "secondary"
declarations in the <filename>named.conf</filename> file
specify
- zones, not domains. When you ask some other site if it is willing to
- be a slave server for your <emphasis>domain</emphasis>, you are
- actually asking for slave service for some collection of zones.
+ zones, not domains. When BIND asks some other site if it is willing to
+ be a secondary server for a <emphasis>domain</emphasis>, it is
+ actually asking for secondary service for some collection of <emphasis>zones</emphasis>.
</para>
</section>
<command>dig</command> (<xref linkend="diagnostic_tools"/>).
</para>
- <section xml:id="primary_master"><info><title>The Primary Master</title></info>
+ <section xml:id="primary_master"><info><title>The Primary Server</title></info>
<para>
- The authoritative server where the master copy of the zone
+ The authoritative server where the main copy of the zone
data is maintained is called the
- <emphasis>primary master</emphasis> server, or simply the
+ <emphasis>primary</emphasis> (or
+ <command>master</command>) server, or simply the
<emphasis>primary</emphasis>. Typically it loads the zone
contents from some local file edited by humans or perhaps
generated mechanically from some other local file which is
</para>
<para>
- In some cases, however, the master file may not be edited
+ In some cases, however, the zone file may not be edited
by humans at all, but may instead be the result of
<emphasis>dynamic update</emphasis> operations.
</para>
</section>
- <section xml:id="slave_server"><info><title>Slave Servers</title></info>
+ <section xml:id="slave_server"><info><title>Secondary Servers</title></info>
<para>
- The other authoritative servers, the <emphasis>slave</emphasis>
- servers (also known as <emphasis>secondary</emphasis> servers)
- load the zone contents from another server using a replication
+ The other authoritative servers, called the
+ <emphasis>secondary</emphasis>
+ (or <command>slave</command>) servers, load the zone
+ contents from another server using a replication
process known as a <emphasis>zone transfer</emphasis>.
- Typically the data are transferred directly from the primary
+ Typically the data is transferred directly from the primary
master, but it is also possible to transfer it from another
- slave. In other words, a slave server may itself act as a
- master to a subordinate slave server.
+ secondary. In other words, a secondary server may itself act as a
+ primary to a subordinate secondary server.
</para>
<para>
- Periodically, the slave server must send a refresh query to
+ Periodically, the secondary server must send a refresh query to
determine whether the zone contents have been updated. This
- is done by sending a query for the zone's SOA record and
+ is done by sending a query for the zone's Start of Authority (SOA) record and
checking whether the SERIAL field has been updated; if so,
a new transfer request is initiated. The timing of these
refresh queries is controlled by the SOA REFRESH and RETRY
<para>
If the zone data cannot be updated within the time specified
by the SOA EXPIRE option (up to a hard-coded maximum of
- 24 weeks) then the slave zone expires and will no longer
- respond to queries.
+ 24 weeks), the secondary zone expires and no longer
+ responds to queries.
</para>
</section>
<section xml:id="stealth_server"><info><title>Stealth Servers</title></info>
<para>
- Usually all of the zone's authoritative servers are listed in
+ Usually, all of the zone's authoritative servers are listed in
NS records in the parent zone. These NS records constitute
a <emphasis>delegation</emphasis> of the zone from the parent.
The authoritative servers are also listed in the zone file itself,
at the <emphasis>top level</emphasis> or <emphasis>apex</emphasis>
- of the zone. You can list servers in the zone's top-level NS
- records that are not in the parent's NS delegation, but you cannot
- list servers in the parent's delegation that are not present at
- the zone's top level.
+ of the zone. Servers that are not in the parent's NS delegation can be listed in the zone's top-level NS
+ records, but servers that are not present at
+ the zone's top level cannot be listed in the parent's delegation.
</para>
<para>
authoritative for a zone but is not listed in that zone's NS
records. Stealth servers can be used for keeping a local copy of
a
- zone to speed up access to the zone's records or to make sure that
+ zone, to speed up access to the zone's records, or to make sure that
the
zone is available even if all the "official" servers for the zone
are
</para>
<para>
- A configuration where the primary master server itself is a
+ A configuration where the primary server itself is a
stealth server is often referred to as a "hidden primary"
configuration. One use for this configuration is when the primary
- master
- is behind a firewall and therefore unable to communicate directly
+ is behind a firewall and is therefore unable to communicate directly
with the outside world.
</para>
<para>
The length of time for which a record may be retained in
the cache of a caching name server is controlled by the
- Time To Live (TTL) field associated with each resource record.
+ Time-To-Live (TTL) field associated with each resource record.
</para>
<section xml:id="forwarder"><info><title>Forwarding</title></info>
There may be one or more forwarders,
and they are queried in turn until the list is exhausted or an
answer
- is found. Forwarders are typically used when you do not
- wish all the servers at a given site to interact directly with the
+ is found. Forwarders are typically used when it is undesirable
+ for all the servers at a given site to interact directly with the
rest of
- the Internet servers. A typical scenario would involve a number
-
of internal <acronym>DNS</acronym> servers and an
+ the Internet's servers. A typical scenario involves
+ internal <acronym>DNS</acronym> servers and an
Internet firewall. Servers unable
- to pass packets through the firewall would forward to the server
- that can
do it, and that server would query the Internet <acronym>DNS</acronym> servers
- on the internal server's behalf.
+ to pass packets through the firewall forward their requests to the server
+ that can
, and that server queries the Internet <acronym>DNS</acronym> servers
+ on the internal servers' behalf.
</para>
</section>
<para>
The <acronym>BIND</acronym> name server can
simultaneously act as
- a master for some zones, a slave for other zones, and as a caching
+ a primary for some zones, a secondary for other zones, and a caching
(recursive) server for a set of local clients.
</para>
<para>
<acronym>DNS</acronym> hardware requirements have
traditionally been quite modest.
- For many installations, servers that have been pensioned off from
+ For many installations, servers that have been retired from
active duty have performed admirably as <acronym>DNS</acronym> servers.
</para>
<para>
-
The DNSSEC features of <acronym>BIND</acronym> 9
- may prove to be quite
- CPU intensive however, so organizations that make heavy use of these
+
However, the DNSSEC features of <acronym>BIND</acronym> 9
+ may be quite
+ CPU-intensive, so organizations that make heavy use of these
features may wish to consider larger systems for these applications.
<acronym>BIND</acronym> 9 is fully multithreaded, allowing
full utilization of
<section xml:id="cpu_req"><info><title>CPU Requirements</title></info>
<para>
CPU requirements for <acronym>BIND</acronym> 9 range from
- i486-class machines
- for serving of static zones without caching, to enterprise-class
- machines if you intend to process many dynamic updates and DNSSEC
- signed zones, serving many thousands of queries per second.
+ i386-class machines,
+ for serving static zones without caching, to enterprise-class
+ machines to process many dynamic updates and DNSSEC-signed zones,
+ serving many thousands of queries per second.
</para>
</section>
<section xml:id="mem_req"><info><title>Memory Requirements</title></info>
<para>
- The memory of the server has to be large enough to fit the
- cache and zones loaded off disk. The <command>max-cache-size</command>
- option can be used to limit the amount of memory used by the cache,
+ Server memory must be sufficient to hold both the
+ cache and the zones loaded from disk. The <command>max-cache-size</command>
+ option can limit the amount of memory used by the cache,
at the expense of reducing cache hit rates and causing more <acronym>DNS</acronym>
traffic.
- Additionally, if additional section caching
+ If additional section caching
(<xref linkend="acache"/>) is enabled,
the <command>max-acache-size</command> option can be used to
limit the amount
of memory used by the mechanism.
It is still good practice to have enough memory to load
- all zone and cache data into memory — unfortunately, the best
+ all zone and cache data into memory; unfortunately, the best
way
to determine this for a given installation is to watch the name server
- in operation. After a few weeks the server process should reach
+ in operation. After a few weeks, the server process should reach
a relatively stable size where entries are expiring from the cache as
fast as they are being inserted.
</para>
-->
</section>
- <section xml:id="intensive_env"><info><title>Name Server Intensive Environment Issues</title></info>
+ <section xml:id="intensive_env"><info><title>Name Server-Intensive Environment Issues</title></info>
<para>
- For name server intensive environments, there are two alternative
- configurations that may be used. The first is where clients and
+ For name server-intensive environments, there are two
+ configurations that may be used. The first is one where clients and
any second-level internal name servers query a main name server, which
- has enough memory to build a large cache. This approach minimizes
+ has enough memory to build a large cache; this approach minimizes
the bandwidth used by external name lookups. The second alternative
is to set up second-level internal name servers to make queries
independently.
- In this configuration, none of the individual machines needs to
+ In this configuration, none of the individual machines need to
have as much memory or CPU power as in the first alternative, but
this has the disadvantage of making many more external queries,
as none of the name servers share their cached data.
<section xml:id="supported_os"><info><title>Supported Operating Systems</title></info>
<para>
- ISC <acronym>BIND</acronym> 9 compiles and runs on a large
- number
- of Unix-like operating systems and on
- Microsoft Windows Server 2003 and 2008, and Windows XP and Vista.
+ ISC <acronym>BIND</acronym> 9 compiles and runs on many
+ Unix-like operating systems and on
+ Microsoft Windows Server 2012 R2, 2016 and Windows 10.
For an up-to-date
- list of supported systems, see the README file in the top level
+ list of supported systems, see the PLATFORMS.md file in the top-level
directory
of the BIND 9 source distribution.
</para>
<chapter xml:id="Bv9ARM.ch03"><info><title>Name Server Configuration</title></info>
<para>
- In this chapter we provide some suggested configurations along
+ In this chapter we provide some suggested configurations, along
with guidelines for their use. We suggest reasonable values for
certain option settings.
</para>
name server for use by clients internal to a corporation. All
queries
from outside clients are refused using the <command>allow-query</command>
- option. Alternatively, the same effect could be achieved using
+ option. The same effect can be achieved using
suitable
firewall rules.
</para>
<para>
This sample configuration is for an authoritative-only server
- that is the master server for "<filename>example.com</filename>"
- and a slave for the subdomain "<filename>eng.example.com</filename>".
+ that is the primary server for "<filename>example.com</filename>"
+ and a secondary server for the subdomain "<filename>eng.example.com</filename>".
</para>
<programlisting>
file "localhost.rev";
notify no;
};
-// We are the master server for example.com
+// We are the primary server for example.com
zone "example.com" {
type master;
file "example.com.db";
- // IP addresses of slave servers allowed to
+ // IP addresses of secondary servers allowed to
// transfer example.com
allow-transfer {
192.168.4.14;
192.168.5.53;
};
};
-// We are a slave server for eng.example.com
+// We are a secondary server for eng.example.com
zone "eng.example.com" {
type slave;
file "eng.example.com.bk";
- // IP address of eng.example.com master server
+ // IP address of eng.example.com primary server
masters { 192.168.4.12; };
};
</programlisting>
</para>
<para>
- For example, if you have three WWW servers with network addresses
- of 10.0.0.1, 10.0.0.2 and 10.0.0.3, a set of records such as the
- following means that clients will connect to each machine one third
+ For example, assuming three HTTP servers with network addresses
+ of 10.0.0.1, 10.0.0.2, and 10.0.0.3, a set of records such as the
+ following means that clients will connect to each machine one-third
of the time:
</para>
</tgroup>
</informaltable>
<para>
- When a resolver queries for these records, <acronym>BIND</acronym> will rotate
- them and respond to the query with the records in a different
- order. In the example above, clients will randomly receive
+ When a resolver queries for these records, <acronym>BIND</acronym> rotates
+ them and responds to the query with the records in a different
+ order. In the example above, clients randomly receive
records in the order 1, 2, 3; 2, 3, 1; and 3, 1, 2. Most clients
- will use the first record returned and discard the rest.
+ use the first record returned and discard the rest.
</para>
<para>
For more detail on ordering responses, check the
<section xml:id="tools"><info><title>Tools for Use With the Name Server Daemon</title></info>
<para>
This section describes several indispensable diagnostic,
- administrative and monitoring tools available to the system
+ administrative, and monitoring tools available to the system
administrator for controlling and debugging the name server
daemon.
</para>
<section xml:id="diagnostic_tools"><info><title>Diagnostic Tools</title></info>
<para>
The <command>dig</command>, <command>host</command>, and
- <command>nslookup</command> programs are all command
- line tools
+ <command>nslookup</command> programs are all command-line tools
for manually querying name servers. They differ in style and
output format.
</para>
<command>dig</command>
is the most versatile and complete of these lookup tools.
It has two modes: simple interactive
- mode for a single query, and batch mode which executes a
+ mode for a single query, and batch mode, which executes a
query for
each in a list of several query lines. All query options are
accessible
<arg choice="opt" rep="norepeat">%<replaceable>comment</replaceable></arg>
</cmdsynopsis>
<para>
- The usual simple use of <command>dig</command> will take the form
+ The usual simple use of <command>dig</command> takes the form
</para>
<simpara>
<command>dig @server domain query-type query-class</command>
has two modes: interactive and
non-interactive. Interactive mode allows the user to
query name servers for information about various
- hosts and domains or to print a list of hosts in a
+ hosts and domains, or to print a list of hosts in a
domain. Non-interactive mode is used to print just
the name and requested information for a host or
domain.
</cmdsynopsis>
<para>
Interactive mode is entered when no arguments are given (the
- default name server will be used) or when the first argument
+ default name server is used) or when the first argument
is a
- hyphen (`-') and the second argument is the host name or
+ hyphen ("-") and the second argument is the host name or
Internet address
of a name server.
</para>
<listitem>
<para>
The <command>named-checkzone</command> program
- checks a master file for
+ checks a zone file for
syntax and consistency.
</para>
<cmdsynopsis label="Usage" sepchar=" ">
<term><command>named-compilezone</command></term>
<listitem>
<para>
- Similar to <command>named-checkzone,</command> but
+ This tool is similar to <command>named-checkzone,</command> but
it always dumps the zone content to a specified file
(typically in a different format).
</para>
(<command>rndc</command>) program allows the
system
administrator to control the operation of a name server.
- Since <acronym>BIND</acronym> 9.2, <command>rndc</command>
- supports all the commands of the BIND 8 <command>ndc</command>
- utility except <command>ndc start</command> and
- <command>ndc restart</command>, which were also
- not supported in <command>ndc</command>'s
- channel mode.
- If you run <command>rndc</command> without any
- options
- it will display a usage message as follows:
+ If <command>rndc</command> is run without any
+ options,
+ it displays a usage message as follows:
</para>
<cmdsynopsis label="Usage" sepchar=" ">
<command>rndc</command>
alternate
location can be specified with the <option>-c</option>
option. If the configuration file is not found,
- <command>rndc</command> will also look in
+ <command>rndc</command> also looks in
<filename>/etc/rndc.key</filename> (or whatever
<varname>sysconfdir</varname> was defined when
the <acronym>BIND</acronym> build was
<para>
The format of the configuration file is similar to
- that of <filename>named.conf</filename>, but
+ that of <filename>named.conf</filename>, but is
limited to
- only four statements, the <command>options</command>,
- <command>key</command>, <command>server</command> and
+ only four statements: the <command>options</command>,
+ <command>key</command>, <command>server</command>, and
<command>include</command>
statements. These statements are what associate the
secret keys to the servers with which they are meant to
<command>default-server</command>, <command>default-key</command>,
and <command>default-port</command>.
<command>default-server</command> takes a
- host name or address argument and represents the server
- that will
- be contacted if no <option>-s</option>
+ host name or address argument and represents the server
+ that
+ is contacted if no <option>-s</option>
option is provided on the command line.
<command>default-key</command> takes
the name of a key as its argument, as defined by a <command>key</command> statement.
The <command>key</command> statement has two
clauses:
<command>algorithm</command> and <command>secret</command>.
- While the configuration parser will accept any string as the
+ While the configuration parser accepts any string as the
argument
- to algorithm, currently only the strings
+ to <command>algorithm</command>, currently only the strings
"<userinput>hmac-md5</userinput>",
"<userinput>hmac-sha1</userinput>",
"<userinput>hmac-sha224</userinput>",
"<userinput>hmac-sha256</userinput>",
- "<userinput>hmac-sha384</userinput>"
+ "<userinput>hmac-sha384</userinput>",
and "<userinput>hmac-sha512</userinput>"
- have any meaning. The secret is a Base64 encoded string
+ have any meaning. The secret is a Base64-encoded string
as specified in RFC 3548.
</para>
<para>
This file, if installed as <filename>/etc/rndc.conf</filename>,
- would allow the command:
+ allows the command:
</para>
<para>
</para>
<para>
- to connect to 127.0.0.1 port 953 and cause the name server
- to reload, if a name server on the local machine were
+ to connect to 127.0.0.1 port 953 and causes the name server
+ to reload, if a name server on the local machine is
running with
following controls statements:
</para>
</programlisting>
<para>
- and it had an identical key statement for
+ and it has an identical key statement for
<literal>rndc_key</literal>.
</para>
<para>
Running the <command>rndc-confgen</command>
- program will
- conveniently create a <filename>rndc.conf</filename>
- file for you, and also display the
+ program
+ conveniently creates an <filename>rndc.conf</filename>
+ file, and also displays the
corresponding <command>controls</command>
- statement that you need to
+ statement needed to
add to <filename>named.conf</filename>.
Alternatively,
- you can run <command>rndc-confgen -a</command>
+ it is possible to run <command>rndc-confgen -a</command>
to set up
- a <filename>rndc.key</filename> file and not
+ an <filename>rndc.key</filename> file and not
modify
<filename>named.conf</filename> at all.
</para>
<section xml:id="signals"><info><title>Signals</title></info>
<para>
- Certain UNIX signals cause the name server to take specific
+ Certain Unix signals cause the name server to take specific
actions, as described in the following table. These signals can
be sent using the <command>kill</command> command.
</para>
<section xml:id="notify"><info><title>Notify</title></info>
<para>
- <acronym>DNS</acronym> NOTIFY is a mechanism that allows master
- servers to notify their slave servers of changes to a zone's data. In
- response to a <command>NOTIFY</command> from a master server, the
- slave will check to see that its version of the zone is the
- current version and, if not, initiate a zone transfer.
+ <acronym>DNS</acronym> NOTIFY is a mechanism that allows primary
+ servers to notify their secondary servers of changes to a zone's data. In
+ response to a <command>NOTIFY</command> from a primary server, the
+ secondary checks to see that its version of the zone is the
+ current version and, if not, initiates a zone transfer.
</para>
<para>
</para>
<note><simpara>
- As a slave zone can also be a master to other slaves, <command>named</command>,
+ As a secondary zone can also be a primary to other secondaries, <command>named</command>,
by default, sends <command>NOTIFY</command> messages for every zone
- it loads. Specifying <command>notify master-only;</command> will
- cause <command>named</command> to only send <command>NOTIFY</command> for master
+ it loads. Specifying <command>notify primary-only;</command>
+ causes <command>named</command> to only send <command>NOTIFY</command> for primary
zones that it loads.
</simpara></note>
<section xml:id="dynamic_update"><info><title>Dynamic Update</title></info>
<para>
- Dynamic Update is a method for adding, replacing or deleting
- records in a master server by sending it a special form of DNS
+ Dynamic Update is a method for adding, replacing, or deleting
+ records in a primary server by sending it a special form of DNS
messages. The format and meaning of these messages is specified
in RFC 2136.
</para>
<para>
If the zone's <command>update-policy</command> is set to
<userinput>local</userinput>, updates to the zone
- will be permitted for the key <varname>local-ddns</varname>,
- which will be generated by <command>named</command> at startup.
+ are permitted for the key <varname>local-ddns</varname>,
+ which is generated by <command>named</command> at startup.
See <xref linkend="dynamic_update_policies"/> for more details.
</para>
<para>
- Dynamic updates using Kerberos signed requests can be made
- using the TKEY/GSS protocol by setting either the
- <command>tkey-gssapi-keytab</command> option, or alternatively
+ Dynamic updates using Kerberos-signed requests can be made
+ using the TKEY/GSS protocol, either by setting the
+ <command>tkey-gssapi-keytab</command> option, or
by setting both the <command>tkey-gssapi-credential</command>
and <command>tkey-domain</command> options. Once enabled,
- Kerberos signed requests will be matched against the update
+ Kerberos-signed requests are matched against the update
policies for the zone, using the Kerberos principal as the
signer for the request.
</para>
<para>
Updating of secure zones (zones using DNSSEC) follows RFC
- 3007: RRSIG, NSEC and NSEC3 records affected by updates are
+ 3007: RRSIG, NSEC, and NSEC3 records affected by updates are
automatically regenerated by the server using an online
zone key. Update authorization is based on transaction
signatures and an explicit server policy.
</para>
- <section xml:id="journal"><info><title>The journal file</title></info>
+ <section xml:id="journal"><info><title>The Journal File</title></info>
<para>
All changes made to a zone using dynamic update are stored
The name of the journal file is formed by appending the extension
<filename>.jnl</filename> to the name of the
corresponding zone
- file unless specifically overridden. The journal file is in a
+ file, unless specifically overridden. The journal file is in a
binary format and should not be edited manually.
</para>
<para>
- The server will also occasionally write ("dump")
+ The server also occasionally writes ("dumps")
the complete contents of the updated zone to its zone file.
This is not done immediately after
each dynamic update, because that would be too slow when a large
zone is updated frequently. Instead, the dump is delayed by
up to 15 minutes, allowing additional updates to take place.
- During the dump process, transient files will be created
+ During the dump process, transient files are created
with the extensions <filename>.jnw</filename> and
<filename>.jbk</filename>; under ordinary circumstances, these
- will be removed when the dump is complete, and can be safely
+ are removed when the dump is complete, and can be safely
ignored.
</para>
<para>
- When a server is restarted after a shutdown or crash, it will replay
- the journal file to incorporate into the zone any updates that
+ When a server is restarted after a shutdown or crash, it replays
+ the journal file to incorporate into the zone any updates that
took
place after the last zone dump.
</para>
<para>
Changes that result from incoming incremental zone transfers are
also
- journalled in a similar way.
+ journaled in a similar way.
</para>
<para>
The zone files of dynamic zones cannot normally be edited by
hand because they are not guaranteed to contain the most recent
- dynamic changes — those are only in the journal file.
+ dynamic changes; those are only in the journal file.
The only way to ensure that the zone file of a dynamic zone
- is up to date is to run <command>rndc stop</command>.
+ is up-to-date is to run <command>rndc stop</command>.
</para>
<para>
- If you have to make changes to a dynamic zone
- manually, the following procedure will work:
- Disable dynamic updates to the zone using
+ To make changes to a dynamic zone
+ manually, follow these steps:
+ first, disable dynamic updates to the zone using
<command>rndc freeze <replaceable>zone</replaceable></command>.
- This will update the zone's master file with the changes
+ This updates the zone file with the changes
stored in its <filename>.jnl</filename> file.
- Edit the zone file. Run
+ Then, edit the zone file. Finally, run
<command>rndc thaw <replaceable>zone</replaceable></command>
to reload the changed zone and re-enable dynamic updates.
</para>
<para>
<command>rndc sync <replaceable>zone</replaceable></command>
- will update the zone file with changes from the journal file
+ updates the zone file with changes from the journal file
without stopping dynamic updates; this may be useful for viewing
the current zone state. To remove the <filename>.jnl</filename>
file after updating the zone file, use
<para>
The incremental zone transfer (IXFR) protocol is a way for
- slave servers to transfer only changed data, instead of having to
- transfer the entire zone. The IXFR protocol is specified in RFC
+ secondary servers to transfer only changed data, instead of having to
+ transfer an entire zone. The IXFR protocol is specified in RFC
1995. See <xref linkend="proposed_standards"/>.
</para>
<para>
- When acting as a
master, <acronym>BIND</acronym> 9
+ When acting as a
primary server, <acronym>BIND</acronym> 9
supports IXFR for those zones
where the necessary change history information is available. These
- include master zones maintained by dynamic update and slave zones
- whose data was obtained by IXFR. For manually maintained master
- zones, and for slave zones obtained by performing a full zone
+ include primary zones maintained by dynamic update and secondary zones
+ whose data was obtained by IXFR. For manually maintained primary
+ zones, and for secondary zones obtained by performing a full zone
transfer (AXFR), IXFR is supported only if the option
<command>ixfr-from-differences</command> is set
to <userinput>yes</userinput>.
</para>
<para>
- When acting as a slave, <acronym>BIND</acronym> 9 will
- attempt to use IXFR unless
+ When acting as a secondary server, <acronym>BIND</acronym> 9
+ attempts to use IXFR unless
it is explicitly disabled. For more information about disabling
IXFR, see the description of the <command>request-ixfr</command> clause
of the <command>server</command> statement.
<section xml:id="split_dns"><info><title>Split DNS</title></info>
<para>
- Setting up different views, or visibility, of the DNS space to
+ Setting up different views of the DNS space to
internal and external resolvers is usually referred to as a
- <emphasis>Split DNS</emphasis> setup. There are several
- reasons an organization would want to set up its DNS this way.
+ <emphasis>split DNS</emphasis> setup. There are several
+ reasons an organization might want to set up its DNS this way.
</para>
<para>
- One common reason for setting up a DNS system this way is
+ One common reason to use split DNS is
to hide "internal" DNS information from "external" clients on the
- Internet. There is some debate as to whether or not this is actually
+ Internet. There is some debate as to whether this is actually
useful.
Internal DNS information leaks out in many ways (via email headers,
for example) and most savvy "attackers" can find the information
However, since listing addresses of internal servers that
external clients cannot possibly reach can result in
connection delays and other annoyances, an organization may
- choose to use a Split DNS to present a consistent view of itself
+ choose to use split DNS to present a consistent view of itself
to the outside world.
</para>
<para>
- Another common reason for setting up a Split DNS system is
+ Another common reason for setting up a split DNS system is
to allow internal networks that are behind filters or in RFC 1918
space (reserved IP space, as documented in RFC 1918) to resolve DNS
on the Internet. Split DNS can also be used to allow mail from outside
- back in to the internal network.
+ back into the internal network.
</para>
- <section xml:id="split_dns_sample"><info><title>Example split DNS setup</title></info>
+ <section xml:id="split_dns_sample"><info><title>Example Split DNS Setup</title></info>
<para>
Let's say a company named <emphasis>Example, Inc.</emphasis>
(<literal>example.com</literal>)
at all outside of the internal network.
</para>
<para>
- In order to accomplish this, the company will set up two sets
- of name servers. One set will be on the inside network (in the
+ In order to accomplish this, the company sets up two sets
+ of name servers. One set is on the inside network (in the
reserved
- IP space) and the other set will be on bastion hosts, which are
+ IP space) and the other set is on bastion hosts, which are
"proxy"
- hosts that can talk to both sides of its network, in the DMZ.
+ hosts in the DMZ that can talk to both sides of its network.
</para>
<para>
- The internal servers will be configured to forward all queries,
+ The internal servers are configured to forward all queries,
except queries for <filename>site1.internal</filename>, <filename>site2.internal</filename>, <filename>site1.example.com</filename>,
and <filename>site2.example.com</filename>, to the servers
in the
hosts.
</para>
<para>
- The external servers, which are on the bastion hosts, will
- be configured to serve the "public" version of the <filename>site1</filename> and <filename>site2.example.com</filename> zones.
+ The external servers, which are on the bastion hosts, are
+ configured to serve the "public" version of the <filename>site1.example.com</filename> and <filename>site2.example.com</filename> zones.
This could include things such as the host records for public servers
- (<filename>www.example.com</filename> and <filename>ftp.example.com</filename>),
- and mail exchange (MX) records (<filename>a.mx.example.com</filename> and <filename>b.mx.example.com</filename>).
+ (<filename>www.example.com</filename> and <filename>ftp.example.com</filename>)
+ and mail exchange (MX) records (<filename>a.mx.example.com</filename> and <filename>b.mx.example.com</filename>).
</para>
<para>
- In addition, the public <filename>site1</filename> and <filename>site2.example.com</filename> zones
- should have special MX records that contain wildcard (`*') records
+ In addition, the public <filename>site1.example.com</filename> and <filename>site2.example.com</filename> zones
+ should have special MX records that contain wildcard ("*") records
pointing to the bastion hosts. This is needed because external mail
servers do not have any other way of looking up how to deliver mail
- to those internal hosts. With the wildcard records, the mail will
- be delivered to the bastion host, which can then forward it on to
+ to those internal hosts. With the wildcard records, the mail is
+ delivered to the bastion host, which can then forward it on to
internal hosts.
</para>
<para>
<programlisting>* IN MX 10 external1.example.com.</programlisting>
<para>
Now that they accept mail on behalf of anything in the internal
- network, the bastion hosts will need to know how to deliver mail
- to internal hosts. In order for this to work properly, the resolvers
+ network, the bastion hosts need to know how to deliver mail
+ to internal hosts. The resolvers
on
- the bastion hosts will need to be configured to point to the internal
+ the bastion hosts need to be configured to point to the internal
name servers for DNS resolution.
</para>
<para>
- Queries for internal hostnames will be answered by the internal
- servers, and queries for external hostnames will be forwarded back
+ Queries for internal hostnames are answered by the internal
+ servers, and queries for external hostnames are forwarded back
out to the DNS servers on the bastion hosts.
</para>
<para>
- In order for all this to work properly, internal clients will
+ For all of this to work properly, internal clients
need to be configured to query <emphasis>only</emphasis> the internal
name servers for DNS queries. This could also be enforced via
selective
</para>
<para>
If everything has been set properly, <emphasis>Example, Inc.</emphasis>'s
- internal clients will now be able to:
+ internal clients are now able to:
</para>
<itemizedlist>
<listitem>
<simpara>
- Look up any hostnames in the <literal>site1</literal>
+ Look up any hostnames in the <literal>site1.example.com</literal>
and
<literal>site2.example.com</literal> zones.
</simpara>
<simpara>Look up any hostnames on the Internet.</simpara>
</listitem>
<listitem>
- <simpara>Exchange mail with both internal and external people.</simpara>
+ <simpara>Exchange mail with both internal and external users.</simpara>
</listitem>
</itemizedlist>
<para>
- Hosts on the Internet will be able to:
+ Hosts on the Internet are able to:
</para>
<itemizedlist>
<listitem>
<simpara>
- Look up any hostnames in the <literal>site1</literal>
+ Look up any hostnames in the <literal>site1.example.com</literal>
and
<literal>site2.example.com</literal> zones.
</simpara>
</listitem>
<listitem>
<simpara>
- Exchange mail with anyone in the <literal>site1</literal> and
+ Exchange mail with anyone in the <literal>site1.example.com</literal> and
<literal>site2.example.com</literal> zones.
</simpara>
</listitem>
</itemizedlist>
<para>
- Here is an example configuration for the setup we just
+ Here is an example configuration for the setup just
described above. Note that this is only configuration information;
- for information on how to configure your zone files, see <xref linkend="sample_configuration"/>.
+ for information on how to configure the zone files, see <xref linkend="sample_configuration"/>.
</para>
<para>
...
};
-// sample master zone
+// sample primary zone
zone "site1.example.com" {
type master;
file "m/site1.example.com";
allow-transfer { internals; };
};
-// sample slave zone
+// sample secondary zone
zone "site2.example.com" {
type slave;
file "s/site2.example.com";
...
};
-// sample slave zone
+// sample secondary zone
zone "site1.example.com" {
type master;
file "m/site1.foo.com";
clients when IP-based access control is insufficient or needs to
be overridden, or as a way to ensure message authenticity when it
is critical to the integrity of the server, such as with dynamic
- UPDATE messages or zone transfers from a master to a slave server.
+ UPDATE messages or zone transfers from a primary to a secondary server.
</para>
<para>
- This is a guide to setting up TSIG in <acronym>BIND</acronym>.
+ This
section is a guide to setting up TSIG in <acronym>BIND</acronym>.
It describes the configuration syntax and the process of creating
TSIG keys.
</para>
<itemizedlist>
<listitem>
<xref linkend="man.nsupdate"/> supports TSIG via the
- <option>-k</option>, <option>-l</option> and
- <option>-y</option> command line options, or via
+ <option>-k</option>, <option>-l</option>, and
+ <option>-y</option> command-line options, or via
the <command>key</command> command when running
interactively.
</listitem>
<listitem>
<xref linkend="man.dig"/> supports TSIG via the
- <option>-k</option> and <option>-y</option> command
- line options.
+ <option>-k</option> and <option>-y</option>
+ command-line options.
</listitem>
</itemizedlist>
</para>
TSIG keys can be generated using the <command>tsig-keygen</command>
command; the output of the command is a <command>key</command> directive
suitable for inclusion in <filename>named.conf</filename>. The
- key name, algorithm and size can be specified by command line parameters;
+ key name, algorithm, and size can be specified by command-line parameters;
the defaults are "tsig-key", HMAC-SHA256, and 256 bits, respectively.
</para>
<para>
Any string which is a valid DNS name can be used as a key name.
For example, a key to be shared between servers called
<emphasis>host1</emphasis> and <emphasis>host2</emphasis> could
- be called "host1-host2.", and this key could be generated using:
+ be called "host1-host2.", and this key can be generated using:
</para>
<programlisting>
$ tsig-keygen host1-host2. > host1-host2.key
</para>
</section>
- <section><info><title>Loading A New Key</title></info>
+ <section><info><title>Loading a New Key</title></info>
<para>
For a key shared between servers called
<emphasis>host1</emphasis> and <emphasis>host2</emphasis>,
Since this text contains a secret, it
is recommended that either <filename>named.conf</filename> not be
world-readable, or that the <command>key</command> directive
- be stored in a file which is not world-readable, and which is
+ be stored in a file which is not world-readable and which is
included in <filename>named.conf</filename> via the
<command>include</command> directive.
</para>
Once a key has been added to <filename>named.conf</filename> and the
server has been restarted or reconfigured, the server can recognize
the key. If the server receives a message signed by the
- key, it will be able to verify the signature. If the signature
- is valid, the response will be signed using the same key.
+ key, it is able to verify the signature. If the signature
+ is valid, the response is signed using the same key.
</para>
<para>
TSIG keys that are known to a server can be listed using the
<para>
For example, a key may be specified for each server in the
<command>masters</command> statement in the definition of a
- slave zone; in this case, all SOA QUERY messages, NOTIFY
- messages, and zone transfer requests (AXFR or IXFR) will be
+ secondary zone; in this case, all SOA QUERY messages, NOTIFY
+ messages, and zone transfer requests (AXFR or IXFR) are
signed using the specified key. Keys may also be specified
- in the <command>also-notify</command> statement of a master
- or slave zone, causing NOTIFY messages to be signed using
+ in the <command>also-notify</command> statement of a primary
+ or secondary zone, causing NOTIFY messages to be signed using
the specified key.
</para>
<para>
configuration file.
</para>
<para>
- Whenever any server sends a TSIG-signed DNS request, it will expect
+ Whenever any server sends a TSIG-signed DNS request, it expects
the response to be signed with the same key. If a response is not
- signed, or if the signature is not valid, the response will be
+ signed, or if the signature is not valid, the response is
rejected.
</para>
</section>
<section><info><title>TSIG-Based Access Control</title></info>
<para>
TSIG keys may be specified in ACL definitions and ACL directives
- such as <command>allow-query</command>, <command>allow-transfer</command>
+ such as <command>allow-query</command>, <command>allow-transfer</command>,
and <command>allow-update</command>.
The above key would be denoted in an ACL element as
<command>key host1-host2.</command>
</para>
<para>
- An example of an <command>allow-update</command> directive using
+ Here is an example of an <command>allow-update</command> directive using
a TSIG key:
</para>
<programlisting>
</listitem>
<listitem>
If a TSIG-aware server receives a message with a time
- outside of the allowed range, the response will be signed, with
+ outside of the allowed range, the response will be signed but
the TSIG extended error code set to BADTIME, and the time values
will be adjusted so that the response can be successfully
verified.
</listitem>
</itemizedlist>
- In all of the above cases, the server will return a response code
+ In all of the above cases, the server returns a response code
of NOTAUTH (not authenticated).
</para>
</section>
a query of type TKEY to a TKEY-aware server. The query must include
an appropriate KEY record in the additional section, and
must be signed using either TSIG or SIG(0) with a previously
- established key. The server's response, if successful, will
- contain a TKEY record in its answer section. After this transaction,
- both participants will have enough information to calculate a
+ established key. The server's response, if successful,
+ contains a TKEY record in its answer section. After this transaction,
+ both participants have enough information to calculate a
shared secret using Diffie-Hellman key exchange. The shared secret
can then be used by to sign subsequent transactions between the
two servers.
<acronym>BIND</acronym> partially supports DNSSEC SIG(0)
transaction signatures as specified in RFC 2535 and RFC 2931.
SIG(0) uses public/private keys to authenticate messages. Access control
- is performed in the same manner as TSIG keys; privileges can be
+ is performed in the same manner as with TSIG keys; privileges can be
granted or denied in ACL directives based on the key name.
</para>
<para>
- When a SIG(0) signed message is received, it will only be
+ When a SIG(0) signed message is received, it is only
verified if the key is known and trusted by the server. The
- server will not attempt to recursively fetch or validate the
+ server does not attempt to recursively fetch or validate the
key.
</para>
<para>
below. In all cases, the <option>-h</option> option prints a
full list of parameters. Note that the DNSSEC tools require the
keyset files to be in the working directory or the
- directory specified by the <option>-d</option> option, and
- that the tools shipped with BIND 9.2.x and earlier are not compatible
- with the current ones.
+ directory specified by the <option>-d</option> option.
</para>
<para>
There must also be communication with the administrators of
the parent and/or child zone to transmit keys. A zone's security
- status must be indicated by the parent zone for a DNSSEC capable
+ status must be indicated by the parent zone for a DNSSEC-capable
resolver to trust its data. This is done through the presence
or absence of a <literal>DS</literal> record at the
delegation
<para>
For other servers to trust data in this zone, they must
- either be statically configured with this zone's zone key or the
+ be statically configured with either this zone's zone key or the
zone key of another zone above this one in the DNS tree.
</para>
A secure zone must contain one or more zone keys. The
zone keys will sign all other records in the zone, as well as
the zone keys of any secure delegated zones. Zone keys must
- have the same name as the zone, a name type of
- <command>ZONE</command>, and must be usable for
+ have the same name as the zone, have a name type of
+ <command>ZONE</command>, and be usable for
authentication.
It is recommended that zone keys use a cryptographic algorithm
designated as "mandatory to implement" by the IETF; currently
</para>
<para>
- The following command will generate a 768-bit RSASHA1 key for
+ The following command generates a 768-bit RSASHA1 key for
the <filename>child.example</filename> zone:
</para>
</para>
<para>
- Two output files will be produced:
+ Two output files are produced:
<filename>Kchild.example.+005+12345.key</filename> and
<filename>Kchild.example.+005+12345.private</filename>
(where
12345 is an example of a key tag). The key filenames contain
- the key name (<filename>child.example.</filename>),
+ the key name (<filename>child.example.</filename>), the
algorithm (3
is DSA, 1 is RSAMD5, 5 is RSASHA1, etc.), and the key tag (12345 in
this case).
</para>
<para>
- To generate another key with the same properties (but with
- a different key tag), repeat the above command.
+ To generate another key with the same properties but with
+ a different key tag, repeat the above command.
</para>
<para>
The <command>dnssec-keyfromlabel</command> program is used
- to get a key pair from a crypto hardware and build the key
+ to get a key pair from a crypto hardware device and build the key
files. Its usage is similar to <command>dnssec-keygen</command>.
</para>
<para>
Any <filename>keyset</filename> files corresponding to
- secure subzones should be present. The zone signer will
- generate <literal>NSEC</literal>, <literal>NSEC3</literal>
+ secure sub-zones should be present. The zone signer
+ generates <literal>NSEC</literal>, <literal>NSEC3</literal>,
and <literal>RRSIG</literal> records for the zone, as
well as <literal>DS</literal> for the child zones if
- <literal>'-g'</literal> is specified. If <literal>'-g'</literal>
+ <literal>-g</literal> is specified. If <literal>-g</literal>
is not specified, then DS RRsets for the secure child
zones need to be added manually.
</para>
<para>
- The following command signs the zone, assuming it is in a
- file called <filename>zone.child.example</filename>. By
- default, all zone keys which have an available private key are
- used to generate signatures.
+ By default, all zone keys which have an available private key are
+ used to generate signatures. The following command signs the zone, assuming it is in a
+ file called <filename>zone.child.example</filename>:
</para>
<para>
</para>
<para><command>dnssec-signzone</command>
- will also produce a keyset and dsset files and optionally a
- dlvset file. These are used to provide the parent zone
+ also produces keyset and dsset files.
+ These are used to provide the parent zone
administrators with the <literal>DNSKEYs</literal> (or their
corresponding <literal>DS</literal> records) that are the
secure entry point to the zone.
</section>
- <section xml:id="dnssec_config"><info><title>Configuring Servers</title></info>
+ <section xml:id="dnssec_config"><info><title>Configuring Servers for DNSSEC</title></info>
<para>
To enable <command>named</command> to respond appropriately
- to DNS requests from DNSSEC aware clients,
+ to DNS requests from DNSSEC-aware clients,
<command>dnssec-enable</command> must be set to yes.
(This is the default setting.)
</para>
To enable <command>named</command> to validate answers from
other servers, the <command>dnssec-enable</command> option
must be set to <userinput>yes</userinput>, and the
- <command>dnssec-validation</command> options must be set to
+ <command>dnssec-validation</command> option must be set to
<userinput>yes</userinput> or <userinput>auto</userinput>.
</para>
<para>
If <command>dnssec-validation</command> is set to
<userinput>auto</userinput>, then a default
- trust anchor for the DNS root zone will be used.
+ trust anchor for the DNS root zone is used.
If it is set to <userinput>yes</userinput>, however,
then at least one trust anchor must be configured
with a <command>trusted-keys</command> or
for zones that are used to form the first link in the
cryptographic chain of trust. All keys listed in
<command>trusted-keys</command> (and corresponding zones)
- are deemed to exist and only the listed keys will be used
- to validated the DNSKEY RRset that they are from.
+ are deemed to exist and only the listed keys are used
+ to validate the DNSKEY RRset that they are from.
</para>
<para>
<command>managed-keys</command> are trusted keys which are
- automatically kept up to date via RFC 5011 trust anchor
+ automatically kept up-to-date via RFC 5011 trust anchor
maintenance.
</para>
</para>
<para>
-
Unlike <acronym>BIND</acronym> 8, <acronym>BIND</acronym>
+ <acronym>BIND</acronym>
9 does not verify signatures on load, so zone keys for
authoritative zones do not need to be specified in the
configuration file.
</para>
<para>
- After DNSSEC gets established, a typical DNSSEC configuration
- will look something like the following. It has one or
- more public keys for the root. This allows answers from
- outside the organization to be validated. It will also
- have several keys for parts of the namespace the organization
+ After DNSSEC is established, a typical DNSSEC configuration
+ looks something like the following. It has one or
+ more public keys for the root, which allows answers from
+ outside the organization to be validated. It also
+ has several keys for parts of the namespace that the organization
controls. These are here to ensure that <command>named</command>
- is immune to compromises in the DNSSEC components of the security
+ is immune to compromised security in the DNSSEC components
of parent zones.
</para>
<para>
When DNSSEC validation is enabled and properly configured,
- the resolver will reject any answers from signed, secure zones
- which fail to validate, and will return SERVFAIL to the client.
+ the resolver rejects any answers from signed, secure zones
+ which fail to validate, and returns SERVFAIL to the client.
</para>
<para>
<para>
If the validator <emphasis>can</emphasis> prove that the zone
is insecure, then the response is accepted. However, if it
- cannot, then it must assume an insecure response to be a
+ cannot, the validator must assume an insecure response to be a
forgery; it rejects the response and logs an error.
</para>
<para>
<section xml:id="ipv6"><info><title>IPv6 Support in <acronym>BIND</acronym> 9</title></info>
<para>
<acronym>BIND</acronym> 9 fully supports all currently
- defined forms of IPv6 name to address and address to name
- lookups. It will also use IPv6 addresses to make queries when
- running on an IPv6 capable system.
+ defined forms of IPv6 name-to-address and address-to-name
+ lookups. It also uses IPv6 addresses to make queries when
+ running on an IPv6-capable system.
</para>
<para>
but support of binary labels has been completely removed per
RFC 3363.
Many applications in <acronym>BIND</acronym> 9 do not understand
- the binary label format at all any more, and will return an
- error if given.
+ the binary label format at all anymore, and return an
+ error if one is given.
In particular, an authoritative <acronym>BIND</acronym> 9
name server will not load a zone file containing binary labels.
</para>
<para>
The IPv6 AAAA record is a parallel to the IPv4 A record,
and, unlike the deprecated A6 record, specifies the entire
- IPv6 address in a single record. For example,
+ IPv6 address in a single record. For example:
</para>
<programlisting>
the address.
</para>
</section>
- <section><info><title>Address to Name Lookups Using Nibble Format</title></info>
+ <section><info><title>Address-to-Name Lookups Using Nibble Format</title></info>
<para>
When looking up an address in nibble format, the address
resulting name.
For example, the following would provide reverse name lookup for
a host with address
- <literal>2001:db8::1</literal>.
+ <literal>2001:db8::1</literal>:
</para>
<programlisting>
<section xml:id="lightweight_resolver"><info><title>The Lightweight Resolver Library</title></info>
<para>
- Traditionally applications have been linked with a stub resolver
+ Traditionally, applications have been linked with a stub resolver
library that sends recursive DNS queries to a local caching name
server.
</para>
<para>
- IPv6 once introduced new complexity into the resolution process,
+ At first, IPv6 introduced new complexity into the resolution process,
such as following A6 chains and DNAME records, and simultaneous
lookup of IPv4 and IPv6 addresses. Though most of the complexity was
then removed, these are hard or impossible
services to local clients
using a combination of a lightweight resolver library and a resolver
daemon process running on the local host. These communicate using
- a simple UDP-based protocol, the "lightweight resolver protocol"
+ a simple UDP-based protocol, the "lightweight resolver protocol,"
that is distinct from and simpler than the full DNS protocol.
</para>
</section>
</para>
<para>
- By default, applications using the lightweight resolver library will
+ By default, applications using the lightweight resolver library
make
UDP requests to the IPv4 loopback address (127.0.0.1) on port 921.
The
<filename>/etc/resolv.conf</filename>.
</para>
- <para>
- The daemon currently only looks in the DNS, but in the future
- it may use other sources such as <filename>/etc/hosts</filename>,
- NIS, etc.
- </para>
-
<para>
The <command>lwresd</command> daemon is essentially a
caching-only name server that responds to requests using the
resolver protocol rather than the DNS protocol. Because it needs
to run on each host, it is designed to require no or minimal
configuration.
- Unless configured otherwise, it uses the name servers listed on
+ Unless otherwise instructed, it uses the name servers listed on
<command>nameserver</command> lines in <filename>/etc/resolv.conf</filename>
as forwarders, but is also capable of doing the resolution
autonomously if
<para>
The <command>lwresd</command> daemon may also be
configured with a
- <filename>named.conf</filename> style configuration file,
+ <filename>named.conf</filename>-style configuration file,
in
<filename>/etc/lwresd.conf</filename> by default. A name
server may also
</para>
<para>
The number of client queries that the <command>lwresd</command>
- daemon is able to serve can be set using the
+ daemon serves can be set using the
<option>lwres-tasks</option> and <option>lwres-clients</option>
statements in the configuration.
</para>
<chapter xml:id="Bv9ARM.ch06"><info><title><acronym>BIND</acronym> 9 Configuration Reference</title></info>
- <para>
- <acronym>BIND</acronym> 9 configuration is broadly similar
- to <acronym>BIND</acronym> 8; however, there are a few new
- areas
- of configuration, such as views. <acronym>BIND</acronym>
- 8 configuration files should work with few alterations in <acronym>BIND</acronym>
- 9, although more complex configurations should be reviewed to check
- if they can be more efficiently implemented using the new features
- found in <acronym>BIND</acronym> 9.
- </para>
-
- <para>
- <acronym>BIND</acronym> 4 configuration files can be
- converted to the new format
- using the shell script
- <filename>contrib/named-bootconf/named-bootconf.sh</filename>.
- </para>
<section xml:id="configuration_file_elements"><info><title>Configuration File Elements</title></info>
<para>
A list of one or more
<varname>ip_addr</varname>,
<varname>ip_prefix</varname>, <varname>key_id</varname>,
- or <varname>acl_name</varname> elements, see
+ or <varname>acl_name</varname> elements; see
<xref linkend="address_match_lists"/>.
</para>
</entry>
with optional <varname>key_id</varname> and/or
<varname>ip_port</varname>.
A <varname>masters_list</varname> may include other
- <varname>masters_lists</varname>.
+ <varname>masters_list</varname>s.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- A quoted string which will be used as
- a DNS name, for example "<literal>my.test.domain</literal>".
+ A quoted string which is used as
+ a DNS name; for example, <literal>my.test.domain</literal>.
</para>
</entry>
</row>
<entry colname="2">
<para>
One to four integers valued 0 through
- 255 separated by dots (`.'), such as <command>123</command>,
- <command>45.67</command> or <command>89.123.45.67</command>.
+ 255 separated by dots ("."), such as <command>123.45.67</command> or <command>89.123.45.67</command>.
</para>
</entry>
</row>
<entry colname="2">
<para>
An IPv6 address, such as <command>2001:db8::1234</command>.
- IPv6 scoped addresses that have ambiguity on their
+ IPv6-scoped addresses that have ambiguity on their
scope zones must be disambiguated by an appropriate
- zone ID with the percent character (`%') as
+ zone ID with the percent character ("%") as a
delimiter. It is strongly recommended to use
string zone names rather than numeric identifiers,
- in order to be robust against system configuration
+ to be robust against system configuration
changes. However, since there is no standard
mapping for such names and identifier values,
- currently only interface names as link identifiers
+ only interface names as link identifiers
are supported, assuming one-to-one mapping between
interfaces and links. For example, a link-local
address <command>fe80::1</command> on the link
attached to the interface <command>ne0</command>
can be specified as <command>fe80::1%ne0</command>.
Note that on most systems link-local addresses
- always have the ambiguity, and need to be
+ always have ambiguity and need to be
disambiguated.
</para>
</entry>
through 65535, with values
below 1024 typically restricted to use by processes running
as root.
- In some cases, an asterisk (`*') character can be used as a
+ In some cases, an asterisk ("*") character can be used as a
placeholder to
select a random high-numbered port.
</para>
<entry colname="2">
<para>
An IP network specified as an <varname>ip_addr</varname>,
- followed by a slash (`/') and then the number of bits in the
+ followed by a slash ("/") and then the number of bits in the
netmask.
- Trailing zeros in a <varname>ip_addr</varname>
- may omitted.
+ Trailing zeros in an <varname>ip_addr</varname>
+ may be omitted.
For example, <command>127/8</command> is the
network <command>127.0.0.0</command> with
netmask <command>255.0.0.0</command> and <command>1.2.3.0/28</command> is
network <command>1.2.3.0</command> with netmask <command>255.255.255.240</command>.
</para>
<para>
- When specifying a prefix involving a IPv6 scoped address
- the scope may be omitted. In that case the prefix will
- match packets from any scope.
+ When specifying a prefix involving a IPv6-scoped address,
+ the scope may be omitted. In that case, the prefix
+ matches packets from any scope.
</para>
</entry>
</row>
<entry colname="2">
<para>
A non-negative real number that can be specified to
- the nearest one hundredth. Up to five digits can be
+ the nearest one-hundredth. Up to five digits can be
specified before a decimal point, and up to two
digits after, so the maximum value is 99999.99.
Acceptable values might be further limited by the
- context in which it is used.
+ contexts in which they are used.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- A quoted string which will be used as
+ A quoted string which is used as
a pathname, such as <filename>zones/master/my.test.domain</filename>.
</para>
</entry>
For example,
<userinput>range 1024 65535</userinput> represents
ports from 1024 through 65535.
- In either case an asterisk (`*') character is not
+ In either case an asterisk ("*") character is not
allowed as a valid <varname>ip_port</varname>.
</para>
</entry>
use a more limited range within these extremes.
In most cases, setting a value to 0 does not
literally mean zero; it means "undefined" or
- "as big as possible", depending on the context.
+ "as big as possible," depending on the context.
See the explanations of particular parameters
that use <varname>size_spec</varname>
for details on how they interpret its use.
</para>
<para>
<varname>unlimited</varname> generally means
- "as big as possible", and is usually the best
+ "as big as possible," and is usually the best
way to safely set a very large number.
</para>
<para>
</entry>
<entry colname="2">
<para>
- <varname>size_spec</varname> or integer value
- followed by '%' to represent percents.
+ A <varname>size_spec</varname> or integer value
+ followed by "%" to represent percent.
</para>
<para>
The behavior is exactly the same as
<varname>size_spec</varname>, but
- <varname>size_or_percent</varname> allows also
- to specify a positive integer value followed by
- '%' sign to represent percents.
+ <varname>size_or_percent</varname> also allows
+ specifying a positive integer value followed by the
+ "%"" sign to represent percent.
</para>
</entry>
</row>
<para>
One of <userinput>yes</userinput>,
<userinput>no</userinput>, <userinput>notify</userinput>,
- <userinput>notify-passive</userinput>, <userinput>refresh</userinput> or
+ <userinput>notify-passive</userinput>, <userinput>refresh</userinput>, or
<userinput>passive</userinput>.
When used in a zone, <userinput>notify-passive</userinput>,
<userinput>refresh</userinput>, and <userinput>passive</userinput>
- are restricted to slave and stub zones.
+ are restricted to secondary and stub zones.
</para>
</entry>
</row>
<simpara>an IP address (IPv4 or IPv6)</simpara>
</listitem>
<listitem>
- <simpara>an IP prefix (in `/' notation)</simpara>
+ <simpara>an IP prefix (in "/" notation)</simpara>
</listitem>
<listitem>
<simpara>
</itemizedlist>
<para>
- Elements can be negated with a leading exclamation mark (`!'),
+ Elements can be negated with a leading exclamation mark ("!"),
and the match list names "any", "none", "localhost", and
"localnets" are predefined. More information on those names
- can be found in the description of the acl statement.
+ can be found in the description of the <command>acl</command>
+ statement.
</para>
<para>
<command>allow-update-forwarding</command>,
<command>blackhole</command>, and
<command>keep-response-order</command> all use address match
- lists. Similarly, the <command>listen-on</command> option will cause the
+ lists. Similarly, the <command>listen-on</command> option causes the
server to refuse queries on any of the machine's
addresses which do not match the list.
</para>
<para>
Order of insertion is significant. If more than one element
in an ACL is found to match a given IP address or prefix,
- preference will be given to the one that came
+ preference is given to the one that came
<emphasis>first</emphasis> in the ACL definition.
Because of this first-match behavior, an element that
defines a subset of another element in the list should
either is negated. For example, in
<command>1.2.3/24; ! 1.2.3.13;</command>
the 1.2.3.13 element is completely useless because the
- algorithm will match any lookup for 1.2.3.13 to the 1.2.3/24
+ algorithm matches any lookup for 1.2.3.13 to the 1.2.3/24
element. Using <command>! 1.2.3.13; 1.2.3/24</command> fixes
- that problem by having 1.2.3.13 blocked by the negation, but
- all other 1.2.3.* hosts fall through.
+ that problem by blocking 1.2.3.13 via the negation, but
+ all other 1.2.3.* hosts pass through.
</para>
</section>
</section>
<section xml:id="comment_syntax"><info><title>Comment Syntax</title></info>
<para>
- The <acronym>BIND</acronym> 9 comment syntax allows for
+ The <acronym>BIND</acronym> 9 comment syntax allows
comments to appear
anywhere that whitespace may appear in a <acronym>BIND</acronym> configuration
file. To appeal to programmers of all kinds, they can be written
<para>
<programlisting>/* This is a <acronym>BIND</acronym> comment as in C */</programlisting>
<programlisting>// This is a <acronym>BIND</acronym> comment as in C++</programlisting>
- <programlisting># This is a <acronym>BIND</acronym> comment as in common UNIX shells
+ <programlisting># This is a <acronym>BIND</acronym> comment as in common Unix shells
# and perl</programlisting>
</para>
</section>
</para>
<para>
- Shell-style (or perl-style, if you prefer) comments start
+ Shell-style (or perl-style) comments start
with the character <literal>#</literal> (number sign)
and continue to the end of the
physical line, as in C++ comments.
<warning>
<para>
- You cannot use the semicolon (`;') character
- to start a comment such as you would in a zone file. The
+ The semicolon (";") character
+ cannot start a comment, unlike in a zone file. The
semicolon indicates the end of a configuration
statement.
</para>
<para>
A <acronym>BIND</acronym> 9 configuration consists of
statements and comments.
- Statements end with a semicolon. Statements and comments are the
+ Statements end with a semicolon; statements and comments are the
only elements that can appear without enclosing braces. Many
statements contain a block of sub-statements, which are also
terminated with a semicolon.
</entry>
<entry colname="2">
<para>
- defines a named IP address
+ Defines a named IP address
matching list, for access control and other uses.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- declares control channels to be used
+ Declares control channels to be used
by the <command>rndc</command> utility.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- includes a file.
+ Includes a file.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- specifies key information for use in
+ Specifies key information for use in
authentication and authorization using TSIG.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- specifies what the server logs, and where
+ Specifies what information the server logs and where
the log messages are sent.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- configures <command>named</command> to
- also act as a light-weight resolver daemon (<command>lwresd</command>).
+ Configures <command>named</command> to
+ also act as a lightweight resolver daemon (<command>lwresd</command>).
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- defines a named masters list for
- inclusion in stub and slave zones'
+ Defines a named list of primary servers for
+ inclusion in stub and secondary zones'
<command>masters</command> or
<command>also-notify</command> lists.
</para>
</entry>
<entry colname="2">
<para>
- controls global server configuration
+ Controls global server configuration
options and sets defaults for other statements.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- sets certain configuration options on
+ Sets certain configuration options on
a per-server basis.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- declares communication channels to get access to
+ Declares communication channels to get access to
<command>named</command> statistics.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- defines trusted DNSSEC keys.
+ Defines trusted DNSSEC keys.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- lists DNSSEC keys to be kept up to date
+ Lists DNSSEC keys to be kept up-to-date
using RFC 5011 trust anchor maintenance.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- defines a view.
+ Defines a view.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- defines a zone.
+ Defines a zone.
</para>
</entry>
</row>
<para>
The <command>acl</command> statement assigns a symbolic
- name to an address match list. It gets its name from a primary
- use of address match lists: Access Control Lists (ACLs).
+ name to an address match list. It gets its name from one of the primary
+ uses of address match lists: Access Control Lists (ACLs).
</para>
<para>
ACL element is updated to reflect the changes.
Some systems do not provide a way to determine the prefix
lengths of
- local IPv6 addresses.
- In such a case, <command>localnets</command>
+ local IPv6 addresses;
+ in such cases, <command>localnets</command>
only matches the local
IPv6 addresses, just like <command>localhost</command>.
</para>
<para>
The <command>controls</command> statement declares control
- channels to be used by system administrators to control the
+ channels to be used by system administrators to manage the
operation of the name server. These control channels are
used by the <command>rndc</command> utility to send
commands to and retrieve non-DNS results from a name server.
listening at the specified <command>ip_port</command> on the
specified <command>ip_addr</command>, which can be an IPv4 or IPv6
address. An <command>ip_addr</command> of <literal>*</literal> (asterisk) is
- interpreted as the IPv4 wildcard address; connections will be
+ interpreted as the IPv4 wildcard address; connections are
accepted on any of the system's IPv4 addresses.
To listen on the IPv6 wildcard address,
use an <command>ip_addr</command> of <literal>::</literal>.
- If you will only use <command>rndc</command> on the local host,
+ If <command>rndc</command> is only used on the local host,
using the loopback address (<literal>127.0.0.1</literal>
or <literal>::1</literal>) is recommended for maximum security.
</para>
<command>keys</command> clauses.
Connections to the control channel are permitted based on the
<command>address_match_list</command>. This is for simple
- IP address based filtering only; any <command>key_id</command>
+ IP address-based filtering only; any <command>key_id</command>
elements of the <command>address_match_list</command>
are ignored.
</para>
<para>
- A <command>unix</command> control channel is a UNIX domain
+ A <command>unix</command> control channel is a Unix domain
socket listening at the specified path in the file system.
Access to the socket is specified by the <command>perm</command>,
- <command>owner</command> and <command>group</command> clauses.
- Note on some platforms (SunOS and Solaris) the permissions
+ <command>owner</command>, and <command>group</command> clauses.
+ Note on some platforms (SunOS and Solaris), the permissions
(<command>perm</command>) are applied to the parent directory
as the permissions on the socket itself are ignored.
</para>
<para>
If no <command>controls</command> statement is present,
- <command>named</command> will set up a default
+ <command>named</command> sets up a default
control channel listening on the loopback address 127.0.0.1
and its IPv6 counterpart ::1.
In this case, and also when the <command>controls</command> statement
is present but does not have a <command>keys</command> clause,
- <command>named</command> will attempt to load the command channel key
+ <command>named</command> attempts to load the command channel key
from the file <filename>rndc.key</filename> in
<filename>/etc</filename> (or whatever <varname>sysconfdir</varname>
- was specified
as when <acronym>BIND</acronym> was built).
- To create a <filename>rndc.key</filename> file, run
+ was specified when <acronym>BIND</acronym> was built).
+ To create an <filename>rndc.key</filename> file, run
<userinput>rndc-confgen -a</userinput>.
</para>
<para>
- The <filename>rndc.key</filename> feature was created to
- ease the transition of systems from <acronym>BIND</acronym> 8,
- which did not have digital signatures on its command channel
- messages and thus did not have a <command>keys</command> clause.
-
- It makes it possible to use an existing <acronym>BIND</acronym> 8
- configuration file in <acronym>BIND</acronym> 9 unchanged,
- and still have <command>rndc</command> work the same way
- <command>ndc</command> worked in BIND 8, simply by executing the
- command <userinput>rndc-confgen -a</userinput> after BIND 9 is
- installed.
- </para>
-
- <para>
- Since the <filename>rndc.key</filename> feature
- is only intended to allow the backward-compatible usage of
- <acronym>BIND</acronym> 8 configuration files, this
- feature does not
- have a high degree of configurability. You cannot easily change
- the key name or the size of the secret, so you should make a
- <filename>rndc.conf</filename> with your own key if you
- wish to change
- those things. The <filename>rndc.key</filename> file
+ The key name and the size of the secret cannot be easily changed; if it
+ is desirable to change those things, make a
+ <filename>rndc.conf</filename> with a custom key. The <filename>rndc.key</filename> file
also has its
permissions set such that only the owner of the file (the user that
<command>named</command> is running as) can access it.
- If you
- desire greater flexibility in allowing other users to access
- <command>rndc</command> commands, then you need to create
+ For greater flexibility in allowing other users to access
+ <command>rndc</command> commands, create
a
- <filename>rndc.conf</filename> file and make it group
- readable by a group
+ <filename>rndc.conf</filename> file and make it group-readable by a group
that contains the users who should have access.
</para>
<para>
The <replaceable>key_id</replaceable>, also known as the
- key name, is a domain name uniquely identifying the key. It can
+ key name, is a domain name that uniquely identifies the key. It can
be used in a <command>server</command>
statement to cause requests sent to that
server to be signed with this key, or in address match lists to
that specifies a security/authentication algorithm. The
<command>named</command> server supports <literal>hmac-md5</literal>,
<literal>hmac-sha1</literal>, <literal>hmac-sha224</literal>,
- <literal>hmac-sha256</literal>, <literal>hmac-sha384</literal>
+ <literal>hmac-sha256</literal>, <literal>hmac-sha384</literal>,
and <literal>hmac-sha512</literal> TSIG authentication.
Truncated hashes are supported by appending the minimum
- number of required bits preceded by a dash, e.g.
+ number of required bits preceded by a dash, e.g.,
<literal>hmac-sha1-80</literal>. The
<replaceable>secret_string</replaceable> is the secret
- to be used by the algorithm, and is treated as a Base64
- encoded string.
+ to be used by the algorithm, and is treated as a Base64-encoded string.
</para>
</section>
The <command>logging</command> statement configures a
wide
variety of logging options for the name server. Its <command>channel</command> phrase
- associates output methods, format options and severity levels with
+ associates output methods, format options, and severity levels with
a name that can then be used with the <command>category</command> phrase
to select how various classes of messages are logged.
</para>
<para>
Only one <command>logging</command> statement is used to
define
- as many channels and categories as are wanted. If there is no <command>logging</command> statement,
- the logging configuration will be:
+ as many channels and categories as desired. If there is no <command>logging</command> statement,
+ the logging configuration is:
</para>
<programlisting>logging {
If <command>named</command> is started with the
<option>-L</option> option, it logs to the specified file
at startup, instead of using syslog. In this case the logging
- configuration will be:
+ configuration is:
</para>
<programlisting>logging {
</programlisting>
<para>
- In <acronym>BIND</acronym> 9, the logging configuration
+ The logging configuration
is only established when
- the entire configuration file has been parsed. In <acronym>BIND</acronym> 8, it was
- established as soon as the <command>logging</command>
- statement
- was parsed. When the server is starting up, all logging messages
+ the entire configuration file has been parsed. When the server starts up, all logging messages
regarding syntax errors in the configuration file go to the default
channels, or to standard error if the <option>-g</option> option
was specified.
<para>
All log output goes to one or more <emphasis>channels</emphasis>;
- you can make as many of them as you want.
+ there is no limit to the number of channels that can be created.
</para>
<para>
Every channel definition must include a destination clause that
- says whether messages selected for the channel go to a file, to a
- particular syslog facility, to the standard error stream, or are
- discarded. It can optionally also limit the message severity level
- that will be accepted by the channel (the default is
+ says whether messages selected for the channel go to a file, go to a
+ particular syslog facility, go to the standard error stream, or are
+ discarded. The definition can optionally also limit the message severity level
+ that is accepted by the channel (the default is
<command>info</command>), and whether to include a
<command>named</command>-generated time stamp, the
- category name
- and/or severity level (the default is not to include any).
+ category name,
+ and/or the severity level (the default is not to include any).
</para>
<para>
The <command>file</command> destination clause directs
the channel
to a disk file. It can include limitations
- both on how large the file is allowed to become, and how many
+ both on how large the file is allowed to become, and on how many
versions
- of the file will be saved each time the file is opened.
+ of the file are saved each time the file is opened.
</para>
<para>
- If you use the <command>versions</command> log file
- option, then
- <command>named</command> will retain that many backup
+ If the <command>versions</command> log file
+ option is used, then
+ <command>named</command> retains that many backup
versions of the file by
- renaming them when opening. For example, if you choose to keep
+ renaming them when opening. For example, to keep
three old versions
- of the file <filename>lamers.log</filename>, then just
+ of the file <filename>lamers.log</filename>, just
before it is opened
<filename>lamers.log.1</filename> is renamed to
<filename>lamers.log.2</filename>, <filename>lamers.log.0</filename> is renamed
to <filename>lamers.log.1</filename>, and <filename>lamers.log</filename> is
renamed to <filename>lamers.log.0</filename>.
- You can say <command>versions unlimited</command> to
+ The <command>versions unlimited</command> option can be set to
not limit
the number of versions.
If a <command>size</command> option is associated with
<para>
The <command>size</command> option for files is used
to limit log
- growth. If the file ever exceeds the size, then <command>named</command> will
- stop writing to the file unless it has a <command>versions</command> option
+ growth. If the file ever exceeds the size, then <command>named</command>
+ stops writing to the file unless it also has a <command>versions</command> option
associated with it. If backup versions are kept, the files are
rolled as
described above and a new one begun. If there is no
- <command>versions</command> option, no more data will
- be written to the log
+ <command>versions</command> option, no more data is
+ written to the log
until some out-of-band mechanism removes or truncates the log to
less than the
maximum size. The default behavior is not to limit the size of
</para>
<para>
- Example usage of the <command>size</command> and
+ Here is an example using the <command>size</command> and
<command>versions</command> options:
</para>
<command>uucp</command>, <command>cron</command>, <command>authpriv</command>,
<command>ftp</command>, <command>local0</command>, <command>local1</command>,
<command>local2</command>, <command>local3</command>, <command>local4</command>,
- <command>local5</command>, <command>local6</command> and
- <command>local7</command>, however not all facilities
+ <command>local5</command>, <command>local6</command>, and
+ <command>local7</command>; however, not all facilities
are supported on
all operating systems.
- How <command>syslog</command> will handle messages
+ How <command>syslog</command> handles messages
sent to
this facility is described in the <command>syslog.conf</command> man
- page. If you have a system which uses a very old version of <command>syslog</command> that
+ page. On a system which uses a very old version of <command>syslog</command>, which
only uses two arguments to the <command>openlog()</command> function,
then this clause is silently ignored.
</para>
<para>
- On Windows machines syslog messages are directed to the EventViewer.
+ On Windows machines, syslog messages are directed to the EventViewer.
</para>
<para>
The <command>severity</command> clause works like <command>syslog</command>'s
- "priorities", except that they can also be used if you are writing
+ "priorities," except that they can also be used when writing
straight to a file rather than using <command>syslog</command>.
- Messages which are not at least of the severity level given will
- not be selected for the channel; messages of higher severity
+ Messages which are not at least of the severity level given are
+ not selected for the channel; messages of higher severity
levels
- will be accepted.
+ are accepted.
</para>
<para>
- If you are using <command>syslog</command>, then the <command>syslog.conf</command> priorities
- will also determine what eventually passes through. For example,
- defining a channel facility and severity as <command>daemon</command> and <command>debug</command> but
- only logging <command>daemon.warning</command> via <command>syslog.conf</command> will
- cause messages of severity <command>info</command> and
+ When using <command>syslog</command>, the <command>syslog.conf</command> priorities
+ also determine what eventually passes through. For example,
+ defining a channel facility and severity as <command>daemon</command> and <command>debug</command>, but
+ only logging <command>daemon.warning</command> via <command>syslog.conf</command>,
+ causes messages of severity <command>info</command> and
<command>notice</command> to
be dropped. If the situation were reversed, with <command>named</command> writing
messages of only <command>warning</command> or higher,
directs the
channel to the server's standard error stream. This is intended
for
- use when the server is running as a foreground process, for
- example
- when debugging a configuration.
+ use when the server is running as a foreground process, as
+ when debugging a configuration, for example.
</para>
<para>
The server can supply extensive debugging information when
it is in debugging mode. If the server's global debug level is
greater
- than zero, then debugging mode will be active. The global debug
+ than zero, debugging mode is active. The global debug
level is set either by starting the <command>named</command> server
with the <option>-d</option> flag followed by a positive integer,
or by running <command>rndc trace</command>.
The global debug level
can be set to zero, and debugging mode turned off, by running <command>rndc
-notrace</command>. All debugging messages in the server have a debug
- level, and higher debug levels give more detailed output. Channels
+ notrace</command>. All debugging messages in the server have a debug
+ level; higher debug levels give more detailed output. Channels
that specify a specific debug severity, for example:
</para>
</programlisting>
<para>
- will get debugging output of level 3 or less any time the
+ get debugging output of level 3 or less any time the
server is in debugging mode, regardless of the global debugging
level. Channels with <command>dynamic</command>
severity use the
server's global debug level to determine what messages to print.
</para>
<para>
- If <command>print-time</command> has been turned on,
- then
- the date and time will be logged. <command>print-time</command> may
- be specified for a <command>syslog</command> channel,
- but is usually
- pointless since <command>syslog</command> also logs
- the date and
- time. If <command>print-category</command> is
- requested, then the
- category of the message will be logged as well. Finally, if <command>print-severity</command> is
- on, then the severity level of the message will be logged. The <command>print-</command> options may
- be used in any combination, and will always be printed in the
+ If <command>print-time</command> is set to
+ <userinput>yes</userinput>, then the date and time are logged.
+ <command>print-time</command> may be specified for a
+ <command>syslog</command> channel, but is usually
+ unnecessary since <command>syslog</command> also logs
+ the date and time. If <command>print-category</command> is
+ set to <userinput>yes</userinput>, then the
+ category of the message is logged as well. Finally, if
+ <command>print-severity</command> is set, then the severity
+ level of the message is logged.
+ The <command>print-</command> options may
+ be used in any combination, and are always printed in the
following
order: time, category, severity. Here is an example where all
three <command>print-</command> options
</para>
<para>
- If <command>buffered</command> has been turned on the output
- to files will not be flushed after each log entry. By default
+ If <command>buffered</command> has been turned on, the output
+ to files is not flushed after each log entry. By default
all log messages are flushed.
</para>
<para>
There are four predefined channels that are used for
- <command>named</command>'s default logging as follows.
+ <command>named</command>'s default logging, as follows.
If <command>named</command> is started with the
- <option>-L</option> then a
- fifth channel <command>default_logfile</command> is added.
+ <option>-L</option>, then a
+ fifth channel, <command>default_logfile</command>, is added.
How they are
used is described in <xref linkend="the_category_phrase"/>.
</para>
special
property that it only produces output when the server's debug
level is
- nonzero. It normally writes to a file called <filename>named.run</filename>
+ non-zero. It normally writes to a file called <filename>named.run</filename>
in the server's working directory.
</para>
<para>
For security reasons, when the <option>-u</option>
- command line option is used, the <filename>named.run</filename> file
+ command-line option is used, the <filename>named.run</filename> file
is created only after <command>named</command> has
changed to the
new UID, and any debug output generated while <command>named</command> is
- starting up and still running as root is discarded. If you need
- to capture this output, you must run the server with the <option>-L</option>
+ starting - and still running as root - is discarded.
+ To capture this output, run the server with the <option>-L</option>
option to specify a default logfile, or the <option>-g</option>
- option to log to standard error which you can redirect to a file.
+ option to log to standard error which can be redirected to a file.
</para>
<para>
- Once a channel is defined, it cannot be redefined. Thus you
- cannot alter the built-in channels directly, but you can modify
- the default logging by pointing categories at channels you have
- defined.
+ Once a channel is defined, it cannot be redefined.
+ The built-in channels cannot be altered directly, but
+ the default logging can be modified by pointing categories at defined channels.
</para>
</section>
<section xml:id="the_category_phrase"><info><title>The <command>category</command> Phrase</title></info>
<para>
- There are many categories, so you can send the logs you want
- to see wherever you want, without seeing logs you don't want. If
- you don't specify a list of channels for a category, then log
+ There are many categories, so desired logs
+ can be sent anywhere while unwanted logs are ignored. If
+ a list of channels is not specified for a category, log
messages
- in that category will be sent to the <command>default</command> category
- instead. If you don't specify a default category, the following
+ in that category are sent to the <command>default</command> category
+ instead. If no default category is specified, the following
"default default" is used:
</para>
</programlisting>
<para>
- If you start <command>named</command> with the
- <option>-L</option> option then the default category is:
+ If <command>named</command> is started with the
+ <option>-L</option> option, the default category is:
</para>
<programlisting>category default { default_logfile; default_debug; };
</programlisting>
<para>
- As an example, let's say you want to log security events to
- a file, but you also want keep the default logging behavior. You'd
+ As an example, let's say a user wants to log security events to
+ a file, but also wants to keep the default logging behavior. They would
specify the following:
</para>
</programlisting>
<para>
- Following are the available categories and brief descriptions
+ The following are the available categories and brief descriptions
of the types of log information they contain. More
categories may be added in future <acronym>BIND</acronym> releases.
</para>
used to indicate why and how specific queries resulted in
responses which indicate an error. Normally, these messages
will be logged at <command>debug</command> logging levels;
- note, however, that if query logging is active, some will be
+ note, however, that if query logging is active, some are
logged at <command>info</command>. The logging levels are
described below:
</para>
<para>
At <command>debug</command> level 1 or higher - or at
<command>info</command>, when query logging is active - each
- response with response code SERVFAIL will be logged as follows:
+ response with response code SERVFAIL is logged as follows:
</para>
<para>
<computeroutput>client 127.0.0.1#61502: query failed (SERVFAIL) for www.example.com/IN/AAAA at query.c:3880</computeroutput>
<para>
This means an error resulting in SERVFAIL was detected at line
3880 of source file <filename>query.c</filename>. Log messages
- of this level will particularly help identify the cause of
+ of this level are particularly helpful in identifying the cause of
SERVFAIL for an authoritative server.
</para>
<para>
At <command>debug</command> level 2 or higher, detailed
context information about recursive resolutions that resulted in
- SERVFAIL will be logged. The log message will look like this:
+ SERVFAIL is logged. The log message looks like this:
</para>
<para>
<!-- NOTE: newlines and some spaces added so this would fit on page -->
<para>
The first part before the colon shows that a recursive
resolution for AAAA records of www.example.com completed
- in 10.000183 seconds and the final result that led to the
+ in 10.000183 seconds, and the final result that led to the
SERVFAIL was determined at line 2970 of source file
<filename>resolver.c</filename>.
</para>
<para>
- The following part shows the detected final result and the
+ The next part shows the detected final result and the
latest result of DNSSEC validation. The latter is always
"success" when no validation attempt was made. In this example,
this query probably resulted in SERVFAIL because all name
<para>
The number of referrals the resolver received
throughout the resolution process.
- In the above example this is 2, which are most
+ In the above example there are two, which are most
likely com and example.com.
</para>
</entry>
The number of cycles that the resolver tried
remote servers at the <varname>domain</varname>
zone.
- In each cycle the resolver sends one query
+ In each cycle, the resolver sends one query
(possibly resending it, depending on the response)
to each known name server of
the <varname>domain</varname> zone.
at the <varname>domain</varname> zone.
A server is detected to be lame either by an
invalid response or as a result of lookup in
- BIND9's address database (ADB), where lame
+ BIND 9's address database (ADB), where lame
servers are cached.
</para>
</entry>
The number of erroneous results that the
resolver encountered in sending queries
at the <varname>domain</varname> zone.
- One common case is the remote server is
- unreachable and the resolver receives an ICMP
- unreachable error message.
+ One common case is when the remote server is
+ unreachable and the resolver receives an "ICMP
+ unreachable" error message.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Failures of resolving remote server addresses.
+ Failures to resolve remote server addresses.
This is a total number of failures throughout
the resolution process.
</para>
</informaltable>
<para>
At <command>debug</command> level 3 or higher, the same
- messages as those at <command>debug</command> level 1 will be
- logged for other errors than SERVFAIL. Note that negative
+ messages as those at <command>debug</command> level 1 are
+ logged for errors other than SERVFAIL. Note that negative
responses such as NXDOMAIN are not errors, and are not logged
at this debug level.
</para>
<para>
At <command>debug</command> level 4 or higher, the
detailed context information logged at <command>debug</command>
- level 2 will be logged for other errors than SERVFAIL and
- for negative resonses such as NXDOMAIN.
+ level 2 is logged for errors other than SERVFAIL and
+ for negative responses such as NXDOMAIN.
</para>
</section>
</section>
resolver daemon
should accept requests on. If no port is specified, port 921 is
used.
- If this statement is omitted, requests will be accepted on
+ If this statement is omitted, requests are accepted on
127.0.0.1,
port 921.
</para>
instance of a
lightweight resolver daemon to a view in the DNS namespace, so that
the
- response will be constructed in the same manner as a normal DNS
+ response is constructed in the same manner as a normal DNS
query
matching this view. If this statement is omitted, the default view
is
- used, and if there is no default view, an error is triggered.
+ used; if there is no default view, an error is triggered.
</para>
<para>
<filename>/etc/resolv.conf</filename>. It indicates the
minimum
number of dots in a relative domain name that should result in an
- exact match lookup before search path elements are appended.
+ exact-match lookup before search path elements are appended.
</para>
<para>
The <option>lwres-tasks</option> statement specifies the number
- of worker threads the lightweight resolver will dedicate to serving
- clients. By default the number is the same as the number of CPUs on
+ of worker threads the lightweight resolver dedicates to serving
+ clients. By default, the number is the same as the number of CPUs on
the system; this can be overridden using the <option>-n</option>
- command line option when starting the server.
+ command-line option when starting the server.
</para>
<para>
- The <option>lwres-clients</option> specifies
+ The <option>lwres-clients</option> statement specifies
the number of client objects per thread the lightweight
resolver should create to serve client queries.
By default, if the lightweight resolver runs as a part
of <command>named</command>, 256 client objects are
created for each task; if it runs as <command>lwresd</command>,
1024 client objects are created for each thread. The maximum
- value is 32768; higher values will be silently ignored and
- the maximum will be used instead.
+ value is 32768; higher values are silently ignored and
+ the maximum is used instead.
Note that setting too high a value may overconsume
system resources.
</para>
Usage</title></info>
<para><command>masters</command>
- lists allow for a common set of masters to be easily used by
- multiple stub and slave zones in their <command>masters</command>
+ lists allow for a common set of primaries to be easily used by
+ multiple stub and secondary zones in their <command>masters</command>
or <command>also-notify</command> lists.
</para>
</section>
to be used by <acronym>BIND</acronym>. This statement
may appear only
once in a configuration file. If there is no <command>options</command>
- statement, an options block with each option set to its default will
- be used.
+ statement, an options block with each option set to its default is
+ used.
</para>
<variablelist>
<term><command>attach-cache</command></term>
<listitem>
<para>
- Allows multiple views to share a single cache
+ This option allows multiple views to share a single cache
database.
Each view has its own cache database by default, but
if multiple views have the same operational policy
for name resolution and caching, those views can
- share a single cache to save memory and possibly
- improve resolution efficiency by using this option.
+ share a single cache to save memory, and possibly
+ improve resolution efficiency, by using this option.
</para>
<para>
views which are supposed to share a cache, it
creates a cache with the specified name for the
first view of these sharing views.
- The rest of the views will simply refer to the
- already created cache.
+ The rest of the views simply refer to the
+ already-created cache.
</para>
<para>
- One common configuration to share a cache would be to
+ One common configuration to share a cache is to
allow all views to share a single cache.
This can be done by specifying
- the <command>attach-cache</command> as a global
+ <command>attach-cache</command> as a global
option with an arbitrary name.
</para>
<para>
Another possible operation is to allow a subset of
- all views to share a cache while the others to
+ all views to share a cache while the others
retain their own caches.
For example, if there are three views A, B, and C,
and only A and B should share a cache, specify the
- <command>attach-cache</command> option as a view A (or
+ <command>attach-cache</command> option as a view of A (or
B)'s option, referring to the other view name:
</para>
forwarders that can return different answers for the
same question, sharing the answer does not make
sense or could even be harmful.
- It is administrator's responsibility to ensure
+ It is administrator's responsibility to ensure that
configuration differences in different views do
not cause disruption with a shared cache.
</para>
<term><command>directory</command></term>
<listitem>
<para>
- The working directory of the server.
- Any non-absolute pathnames in the configuration file will
- be taken as relative to this directory. The default
+ This sets the working directory of the server.
+ Any non-absolute pathnames in the configuration file are
+ taken as relative to this directory. The default
location for most server output files
- (e.g. <filename>named.run</filename>) is this directory.
+ (e.g., <filename>named.run</filename>) is this directory.
If a directory is not specified, the working directory
- defaults to `<filename>.</filename>', the directory from
+ defaults to "<filename>.</filename>", the directory from
which the server was started. The directory specified
should be an absolute path. It is
<emphasis>strongly recommended</emphasis>
<para>
To enable <command>dnstap</command> at compile time,
the <command>fstrm</command> and <command>protobuf-c</command>
- libraries must be available, and BIND must be configured with
+ libraries must be available, and <acronym>BIND</acronym> must be configured with
<option>--enable-dnstap</option>.
</para>
<para>
for each view. Supported types are <literal>client</literal>,
<literal>auth</literal>, <literal>resolver</literal>, and
<literal>forwarder</literal>. Specifying type
- <literal>all</literal> will cause all <command>dnstap</command>
+ <literal>all</literal> causes all <command>dnstap</command>
messages to be logged, regardless of type.
</para>
<para>
<listitem>
<simpara>
<command>fstrm-set-output-queue-model</command>:
- Controls the queuing semantics to use for queue
+ The queuing semantics to use for queue
objects. The default is <literal>mpsc</literal>
(multiple producer, single consumer); the other
option is <literal>spsc</literal> (single producer,
<term><command>dnstap-output</command></term>
<listitem>
<para>
- Configures the path to which the <command>dnstap</command>
- frame stream will be sent if <command>dnstap</command>
+ This configures the path to which the <command>dnstap</command>
+ frame stream is sent if <command>dnstap</command>
is enabled at compile time and active.
</para>
<para>
The first argument is either <literal>file</literal> or
<literal>unix</literal>, indicating whether the destination
- is a file or a UNIX domain socket. The second argument
+ is a file or a Unix domain socket. The second argument
is the path of the file or socket. (Note: when using a
- socket, <command>dnstap</command> messages will
- only be sent if another process such as
+ socket, <command>dnstap</command> messages are
+ only sent if another process such as
<command>fstrm_capture</command>
(provided with <command>libfstrm</command>) is listening on
the socket.)
<term><command>dnstap-identity</command></term>
<listitem>
<para>
- Specifies an <command>identity</command> string to send in
+ This specifies an <command>identity</command> string to send in
<command>dnstap</command> messages. If set to
<literal>hostname</literal>, which is the default, the
- server's hostname will be sent. If set to
- <literal>none</literal>, no identity string will be sent.
+ server's hostname is sent. If set to
+ <literal>none</literal>, no identity string is sent.
</para>
</listitem>
</varlistentry>
<term><command>dnstap-version</command></term>
<listitem>
<para>
- Specifies a <command>version</command> string to send in
+ This specifies a <command>version</command> string to send in
<command>dnstap</command> messages. The default is the
- version number of the BIND release. If set to
- <literal>none</literal>, no version string will be sent.
+ version number of the <acronym>BIND</acronym> release. If set to
+ <literal>none</literal>, no version string is sent.
</para>
</listitem>
</varlistentry>
this specifies the directory containing GeoIP
database files. By default, the option is set based on
the prefix used to build the <command>libmaxminddb</command>
- module: for example, if the library is installed in
+ module; for example, if the library is installed in
<filename>/usr/local/lib</filename>, then the default
- <command>geoip-directory</command> will be
+ <command>geoip-directory</command> is
<filename>/usr/local/share/GeoIP</filename>. On Windows,
the default is the <command>named</command> working
directory. See <xref linkend="acl"/> for details about
<term><command>key-directory</command></term>
<listitem>
<para>
- When performing dynamic update of secure zones, the
+ This is the
directory where the public and private DNSSEC key files
- should be found, if different than the current working
+ should be found when performing a dynamic update of secure zones, if different than the current working
directory. (Note that this option has no effect on the
paths for files containing non-DNSSEC keys such as
<filename>bind.keys</filename>,
- <filename>rndc.key</filename> or
+ <filename>rndc.key</filename>, or
<filename>session.key</filename>.)
</para>
</listitem>
</para>
<para>
Because the database file is memory mapped, its size is
- limited by the address space of the named process. The
+ limited by the address space of the <command>named</command> process. The
default of 32 megabytes was chosen to be usable with
32-bit <command>named</command> builds. The largest
permitted value is 1 terabyte. Given typical zone
<term><command>managed-keys-directory</command></term>
<listitem>
<para>
- Specifies the directory in which to store the files that
+ This specifies the directory in which to store the files that
track managed DNSSEC keys. By default, this is the working
directory. The directory <emphasis>must</emphasis>
be writable by the effective user ID of the
</para>
<para>
If <command>named</command> is not configured to use views,
- then managed keys for the server will be tracked in a single
+ managed keys for the server are tracked in a single
file called <filename>managed-keys.bind</filename>.
- Otherwise, managed keys will be tracked in separate files,
- one file per view; each file name will be the view name
+ Otherwise, managed keys are tracked in separate files,
+ one file per view; each file name is the view name
(or, if it contains characters that are incompatible with
use as a file name, the SHA256 hash of the view name),
followed by the extension
<filename>.mkeys</filename>.
</para>
<para>
- (Note: in previous releases, file names for views
+ (Note: in earlier releases, file names for views
always used the SHA256 hash of the view name. To ensure
- compatibility after upgrade, if a file using the old
- name format is found to exist, it will be used instead
+ compatibility after upgrading, if a file using the old
+ name format is found to exist, it is used instead
of the new format.)
</para>
</listitem>
<term><command>named-xfer</command></term>
<listitem>
<para>
- <emphasis>This option is obsolete.</emphasis> It
- was used in <acronym>BIND</acronym> 8 to specify
- the pathname to the <command>named-xfer</command>
- program. In <acronym>BIND</acronym> 9, no separate
+ <emphasis>This option is obsolete.</emphasis>
+ In <acronym>BIND</acronym> 9, no separate
<command>named-xfer</command> program is needed;
its functionality is built into the name server.
</para>
<term><command>tkey-gssapi-keytab</command></term>
<listitem>
<para>
- The KRB5 keytab file to use for GSS-TSIG updates. If
+ This is the KRB5 keytab file to use for GSS-TSIG updates. If
this option is set and tkey-gssapi-credential is not
- set, then updates will be allowed with any key
+ set, updates are allowed with any key
matching a principal in the specified keytab.
</para>
</listitem>
<term><command>tkey-gssapi-credential</command></term>
<listitem>
<para>
- The security credential with which the server should
+ This is the security credential with which the server should
authenticate keys requested by the GSS-TSIG protocol.
- Currently only Kerberos 5 authentication is available
- and the credential is a Kerberos principal which the
+ Currently only Kerberos 5 authentication is available;
+ the credential is a Kerberos principal which the
server can acquire through the default system key
file, normally <filename>/etc/krb5.keytab</filename>.
- The location keytab file can be overridden using the
- tkey-gssapi-keytab option. Normally this principal is
+ The location of the keytab file can be overridden using the
+ <command>tkey-gssapi-keytab</command> option. Normally this principal is
of the form "<userinput>DNS/</userinput><varname>server.domain</varname>".
To use GSS-TSIG, <command>tkey-domain</command> must
also be set if a specific keytab is not set with
- tkey-gssapi-keytab.
+ <command>tkey-gssapi-keytab</command>.
</para>
</listitem>
</varlistentry>
<term><command>tkey-domain</command></term>
<listitem>
<para>
- The domain appended to the names of all shared keys
+ This domain is appended to the names of all shared keys
generated with <command>TKEY</command>. When a
client requests a <command>TKEY</command> exchange,
it may or may not specify the desired name for the
- key. If present, the name of the shared key will
- be <varname>client specified part</varname> +
+ key. If present, the name of the shared key is
+ <varname>client-specified part</varname> +
<varname>tkey-domain</varname>. Otherwise, the
- name of the shared key will be <varname>random hex
+ name of the shared key is <varname>random hex
digits</varname> + <varname>tkey-domain</varname>.
In most cases, the <command>domainname</command>
should be the server's domain name, or an otherwise
- non-existent subdomain like
- "_tkey.<varname>domainname</varname>". If you are
+ nonexistent subdomain like
+ "_tkey.<varname>domainname</varname>". If
using GSS-TSIG, this variable must be defined, unless
- you specify a specific keytab using tkey-gssapi-keytab.
+ a specific keytab is specified using <command>tkey-gssapi-keytab</command>.
</para>
</listitem>
</varlistentry>
<term><command>tkey-dhkey</command></term>
<listitem>
<para>
- The Diffie-Hellman key used by the server
+ This is the Diffie-Hellman key used by the server
to generate shared keys with clients using the Diffie-Hellman
mode
of <command>TKEY</command>. The server must be
<term><command>dump-file</command></term>
<listitem>
<para>
- The pathname of the file the server dumps
- the database to when instructed to do so with
+ This is the pathname of the file the server dumps
+ the database to, when instructed to do so with
<command>rndc dumpdb</command>.
If not specified, the default is <filename>named_dump.db</filename>.
</para>
<term><command>memstatistics-file</command></term>
<listitem>
<para>
- The pathname of the file the server writes memory
+ This is the pathname of the file the server writes memory
usage statistics to on exit. If not specified,
the default is <filename>named.memstats</filename>.
</para>
<term><command>lock-file</command></term>
<listitem>
<para>
- The pathname of a file on which <command>named</command> will
- attempt to acquire a file lock when starting up for
- the first time; if unsuccessful, the server will
- will terminate, under the assumption that another
+ This is the pathname of a file on which <command>named</command>
+ attempts to acquire a file lock when starting for
+ the first time; if unsuccessful, the server
+ terminates, under the assumption that another
server is already running. If not specified, the default is
<filename>none</filename>.
</para>
<command>lock-file</command> are ignored if
<command>named</command> is being reloaded or
reconfigured; it is only effective when the server is
- first started up.
+ first started.
</para>
</listitem>
</varlistentry>
<term><command>pid-file</command></term>
<listitem>
<para>
- The pathname of the file the server writes its process ID
+ This is the pathname of the file the server writes its process ID
in. If not specified, the default is
<filename>/var/run/named/named.pid</filename>.
- The PID file is used by programs that want to send signals to
+ The PID file is used by programs that send signals to
the running
name server. Specifying <command>pid-file none</command> disables the
- use of a PID file — no file will be written and any
- existing one will be removed. Note that <command>none</command>
+ use of a PID file; no file is written and any
+ existing one is removed. Note that <command>none</command>
is a keyword, not a filename, and therefore is not enclosed
in
double quotes.
<term><command>recursing-file</command></term>
<listitem>
<para>
- The pathname of the file the server dumps
- the queries that are currently recursing when instructed
+ This is the pathname of the file where the server dumps
+ the queries that are currently recursing, when instructed
to do so with <command>rndc recursing</command>.
If not specified, the default is <filename>named.recursing</filename>.
</para>
<term><command>statistics-file</command></term>
<listitem>
<para>
- The pathname of the file the server appends statistics
- to when instructed to do so using <command>rndc stats</command>.
+ This is the pathname of the file the server appends statistics
+ to, when instructed to do so using <command>rndc stats</command>.
If not specified, the default is <filename>named.stats</filename> in the
server's current directory. The format of the file is
described
<term><command>bindkeys-file</command></term>
<listitem>
<para>
- The pathname of a file to override the built-in trusted
+ This is the pathname of a file to override the built-in trusted
keys provided by <command>named</command>.
See the discussion of <command>dnssec-validation</command>
for details. If not specified, the default is
<term><command>secroots-file</command></term>
<listitem>
<para>
- The pathname of the file the server dumps
- security roots to when instructed to do so with
+ This is the pathname of the file the server dumps
+ security roots to, when instructed to do so with
<command>rndc secroots</command>.
If not specified, the default is
<filename>named.secroots</filename>.
<term><command>session-keyfile</command></term>
<listitem>
<para>
- The pathname of the file into which to write a TSIG
+ This is the pathname of the file into which to write a TSIG
session key generated by <command>named</command> for use by
<command>nsupdate -l</command>. If not specified, the
default is <filename>/var/run/named/session.key</filename>.
<term><command>session-keyname</command></term>
<listitem>
<para>
- The key name to use for the TSIG session key.
- If not specified, the default is "local-ddns".
+ This is the key name to use for the TSIG session key.
+ If not specified, the default is <varname>local-ddns</varname>.
</para>
</listitem>
</varlistentry>
<term><command>session-keyalg</command></term>
<listitem>
<para>
- The algorithm to use for the TSIG session key.
+ This is the algorithm to use for the TSIG session key.
Valid values are hmac-sha1, hmac-sha224, hmac-sha256,
- hmac-sha384, hmac-sha512 and hmac-md5. If not
+ hmac-sha384, hmac-sha512, and hmac-md5. If not
specified, the default is hmac-sha256.
</para>
</listitem>
<term><command>port</command></term>
<listitem>
<para>
- The UDP/TCP port number the server uses for
- receiving and sending DNS protocol traffic.
+ This is the UDP/TCP port number the server uses to
+ receive and send DNS protocol traffic.
The default is 53. This option is mainly intended for server
testing;
- a server using a port other than 53 will not be able to
+ a server using a port other than 53 is not able to
communicate with
the global DNS.
</para>
<term><command>dscp</command></term>
<listitem>
<para>
- The global Differentiated Services Code Point (DSCP)
- value to classify outgoing DNS traffic on operating
+ This is the global Differentiated Services Code Point (DSCP)
+ value to classify outgoing DNS traffic, on operating
systems that support DSCP. Valid values are 0 through 63.
It is not configured by default.
</para>
<term><command>random-device</command></term>
<listitem>
<para>
- The source of entropy to be used by the server. Entropy is
+ This specifies a source of entropy to be used by the server. Entropy is
primarily needed
for DNSSEC operations, such as TKEY transactions and dynamic
update of signed
- zones. This options specifies the device (or file) from which
+ zones. This option specifies the device (or file) from which
to read
- entropy. If this is a file, operations requiring entropy will
+ entropy. If it is a file, operations requiring entropy will
fail when the
- file has been exhausted. If not specified, the default value
+ file has been exhausted. If <command>random-device</command> is not specified, the default value
is
<filename>/dev/random</filename>
(or equivalent) when present, and none otherwise. The
<term><command>preferred-glue</command></term>
<listitem>
<para>
- If specified, the listed type (A or AAAA) will be emitted
+ If specified, the listed type (A or AAAA) is emitted
before other glue
in the additional section of a query response.
The default is to prefer A records when responding
<term><command>root-delegation-only</command></term>
<listitem>
<para>
- Turn on enforcement of delegation-only in TLDs
- (top level domains) and root zones with an optional
+ This turns on enforcement of delegation-only in TLDs
+ (top-level domains) and root zones with an optional
exclude list.
</para>
<para>
DS queries are expected to be made to and be answered by
- delegation only zones. Such queries and responses are
+ delegation-only zones. Such queries and responses are
treated as an exception to delegation-only processing
- and are not converted to NXDOMAIN responses provided
+ and are not converted to NXDOMAIN responses, provided
a CNAME is not discovered at the query name.
</para>
<para>
- If a delegation only zone server also serves a child
- zone it is not always possible to determine whether
- an answer comes from the delegation only zone or the
- child zone. SOA NS and DNSKEY records are apex
- only records and a matching response that contains
+ If a delegation-only zone server also serves a child
+ zone, it is not always possible to determine whether
+ an answer comes from the delegation-only zone or the
+ child zone. SOA NS and DNSKEY records are apex-only
+ records and a matching response that contains
these records or DS is treated as coming from a
child zone. RRSIG records are also examined to see
- if they are signed by a child zone or not. The
- authority section is also examined to see if there
+ if they are signed by a child zone, and the
+ authority section is examined to see if there
is evidence that the answer is from the child zone.
Answers that are determined to be from a child zone
are not converted to NXDOMAIN responses. Despite
- all these checks there is still a possibility of
+ all these checks, there is still a possibility of
false negatives when a child zone is being served.
</para>
<para>
- Similarly false positives can arise from empty nodes
- (no records at the name) in the delegation only zone
- when the query type is not ANY.
+ Similarly, false positives can arise from empty nodes
+ (no records at the name) in the delegation-only zone
+ when the query type is not <varname>ANY</varname>.
</para>
<para>
- Note some TLDs are not delegation only (e.g. "DE", "LV",
- "US" and "MUSEUM"). This list is not exhaustive.
+ Note that some TLDs are not delegation-only; e.g., "DE", "LV",
+ "US", and "MUSEUM". This list is not exhaustive.
</para>
<programlisting>
<term><command>disable-algorithms</command></term>
<listitem>
<para>
- Disable the specified DNSSEC algorithms at and below the
+ This disables the specified DNSSEC algorithms at and below the
specified name.
Multiple <command>disable-algorithms</command>
statements are allowed.
- Only the best match <command>disable-algorithms</command>
- clause will be used to determine which algorithms are used.
+ Only the best-match <command>disable-algorithms</command>
+ clause is used to determine the algorithms.
</para>
<para>
If all supported algorithms are disabled, the zones covered
- by the <command>disable-algorithms</command> will be treated
+ by the <command>disable-algorithms</command> setting are treated
as insecure.
</para>
<para>
Configured trust anchors in <command>trusted-keys</command>
or <command>managed-keys</command> that match a disabled
- algorithm will be ignored and treated as if they were not
- configured at all.
+ algorithm are ignored and treated as if they were not
+ configured.
</para>
</listitem>
</varlistentry>
<term><command>disable-ds-digests</command></term>
<listitem>
<para>
- Disable the specified DS/DLV digest types at and below the
+ This disables the specified DS digest types at and below the
specified name.
Multiple <command>disable-ds-digests</command>
statements are allowed.
- Only the best match <command>disable-ds-digests</command>
- clause will be used to determine which digest types are used.
+ Only the best-match <command>disable-ds-digests</command>
+ clause is used to determine the digest types.
</para>
<para>
If all supported digest types are disabled, the zones covered
- by the <command>disable-ds-digests</command> will be treated
+ by <command>disable-ds-digests</command> are treated
as insecure.
</para>
</listitem>
below a domain specified by the deepest
<command>dnssec-lookaside</command>, and the normal DNSSEC
validation has left the key untrusted, the trust-anchor
- will be appended to the key name and a DLV record will be
+ is appended to the key name and a DLV record is
looked up to see if it can validate the key. If the DLV
record validates a DNSKEY (similarly to the way a DS
- record does) the DNSKEY RRset is deemed to be trusted.
+ record does), the DNSKEY RRset is deemed to be trusted.
</para>
<para>
If <command>dnssec-lookaside</command> is set to
- <userinput>no</userinput>, then dnssec-lookaside
+ <userinput>no</userinput>, then <command>dnssec-lookaside</command>
is not used.
</para>
<para>
- NOTE: The ISC-provided DLV service at
- <literal>dlv.isc.org</literal>, has been shut down.
+ Note: the ISC-provided DLV service at
+ <literal>dlv.isc.org</literal> has been shut down.
The <command>dnssec-lookaside auto;</command>
configuration option, which set <command>named</command>
- up to use ISC DLV with minimal configuration, has
+ to use ISC DLV with minimal configuration, has
accordingly been removed.
</para>
</listitem>
<term><command>dnssec-must-be-secure</command></term>
<listitem>
<para>
- Specify hierarchies which must be or may not be secure
+ This specifies hierarchies which must be or may not be secure
(signed and validated). If <userinput>yes</userinput>,
- then <command>named</command> will only accept answers if
+ then <command>named</command> only accepts answers if
they are secure. If <userinput>no</userinput>, then normal
- DNSSEC validation applies allowing for insecure answers to
+ DNSSEC validation applies, allowing insecure answers to
be accepted. The specified domain must be under a
<command>trusted-keys</command> or
<command>managed-keys</command> statement, or
</para>
<para>
Compatible IPv6 prefixes have lengths of 32, 40, 48, 56,
- 64 and 96 as per RFC 6052. Bits 64..71 inclusive must
- be zero with the most significate bit of the prefix in
+ 64, and 96, per RFC 6052. Bits 64..71 inclusive must
+ be zero, with the most significant bit of the prefix in
position 0.
</para>
<para>
- Additionally a reverse IP6.ARPA zone will be created for
+ In addition, a reverse IP6.ARPA zone is created for
the prefix to provide a mapping from the IP6.ARPA names
to the corresponding IN-ADDR.ARPA names using synthesized
CNAMEs. <command>dns64-server</command> and
<command>dns64-contact</command> can be used to specify
the name of the server and contact for the zones. These
- are settable at the view / options level. These are
- not settable on a per-prefix basis.
+ can be set at the view/options level but not
+ on a per-prefix basis.
</para>
<para>
Each <command>dns64</command> supports an optional
Each <command>dns64</command> supports an optional
<command>mapped</command> ACL that selects which
IPv4 addresses are to be mapped in the corresponding
- A RRset. If not defined it defaults to
+ A RRset. If not defined, it defaults to
<userinput>any;</userinput>.
</para>
<para>
- Normally, DNS64 won't apply to a domain name that
- owns one or more AAAA records; these records will
- simply be returned. The optional
+ Normally, DNS64 does not apply to a domain name that
+ owns one or more AAAA records; these records are
+ simply returned. The optional
<command>exclude</command> ACL allows specification
- of a list of IPv6 addresses that will be ignored
- if they appear in a domain name's AAAA records, and
- DNS64 will be applied to any A records the domain
+ of a list of IPv6 addresses that are ignored
+ if they appear in a domain name's AAAA records;
+ DNS64 is applied to any A records the domain
name owns. If not defined, <command>exclude</command>
defaults to ::ffff:0.0.0.0/96.
</para>
</para>
<para>
If <command>recursive-only</command> is set to
- <command>yes</command> the DNS64 synthesis will
- only happen for recursive queries. The default
+ <command>yes</command>, the DNS64 synthesis
+ only happens for recursive queries. The default
is <command>no</command>.
</para>
<para>
If <command>break-dnssec</command> is set to
- <command>yes</command> the DNS64 synthesis will
- happen even if the result, if validated, would
+ <command>yes</command>, the DNS64 synthesis
+ happens even if the result, if validated, would
cause a DNSSEC validation failure. If this option
is set to <command>no</command> (the default), the DO
is set on the incoming query, and there are RRSIGs on
- the applicable records, then synthesis will not happen.
+ the applicable records, then synthesis does not happen.
</para>
<programlisting>
acl rfc1918 { 10/8; 192.168/16; 172.16/12; };
<listitem>
<para>
When a zone is configured with <command>auto-dnssec
- maintain;</command> its key repository must be checked
+ maintain;</command>, its key repository must be checked
periodically to see if any new keys have been added
or any existing keys' timing metadata has been updated
(see <xref linkend="man.dnssec-keygen"/> and
<xref linkend="dynamic_update_policies"/>), and
if <command>named</command> has access to the
private signing key(s) for the zone, then
- <command>named</command> will automatically sign all new
- or changed records and maintain signatures for the zone
+ <command>named</command> automatically signs all new
+ or changed records and maintains signatures for the zone
by regenerating RRSIG records whenever they approach
their expiration date.
</para>
<para>
If the option is changed to <literal>no-resign</literal>,
- then <command>named</command> will sign all new or
+ then <command>named</command> signs all new or
changed records, but scheduled maintenance of
signatures is disabled.
</para>
<para>
With either of these settings, <command>named</command>
- will reject updates to a DNSSEC-signed zone when the
+ rejects updates to a DNSSEC-signed zone when the
signing keys are inactive or unavailable to
<command>named</command>. (A planned third option,
<literal>external</literal>, will disable all automatic
<term><command>nta-lifetime</command></term>
<listitem>
<para>
- Species the default lifetime, in seconds,
- that will be used for negative trust anchors added
+ This specifies the default lifetime, in seconds,
+ for negative trust anchors added
via <command>rndc nta</command>.
</para>
<para>
A negative trust anchor selectively disables
DNSSEC validation for zones that are known to be
- failing because of misconfiguration rather than
+ failing because of misconfiguration, rather than
an attack. When data to be validated is
at or below an active NTA (and above any other
- configured trust anchors), <command>named</command> will
- abort the DNSSEC validation process and treat the data as
+ configured trust anchors), <command>named</command>
+ aborts the DNSSEC validation process and treats the data as
insecure rather than bogus. This continues until the
NTA's lifetime is elapsed. NTAs persist
across <command>named</command> restarts.
</para>
<para>
- For convenience, TTL-style time unit suffixes can be
- used to specify the NTA lifetime in seconds, minutes
+ For convenience, TTL-style time-unit suffixes can be
+ used to specify the NTA lifetime in seconds, minutes,
or hours. <option>nta-lifetime</option> defaults to
- one hour. It cannot exceed one week.
+ one hour; it cannot exceed one week.
</para>
</listitem>
</varlistentry>
<term><command>nta-recheck</command></term>
<listitem>
<para>
- Species how often to check whether negative
+ This specifies how often to check whether negative
trust anchors added via <command>rndc nta</command>
are still necessary.
</para>
it temporarily disables DNSSEC validation for that
domain. In the interest of ensuring that DNSSEC
validation is turned back on as soon as possible,
- <command>named</command> will periodically send a
+ <command>named</command> periodically sends a
query to the domain, ignoring negative trust anchors,
to find out whether it can now be validated. If so,
the negative trust anchor is allowed to expire early.
to zero.
</para>
<para>
- For convenience, TTL-style time unit suffixes can be
+ For convenience, TTL-style time-unit suffixes can be
used to specify the NTA recheck interval in seconds,
- minutes or hours. The default is five minutes. It
- cannot be longer than <option>nta-lifetime</option>
- (which cannot be longer than a week).
+ minutes, or hours. The default is five minutes. It
+ cannot be longer than <option>nta-lifetime</option>,
+ which cannot be longer than a week.
</para>
</listitem>
</varlistentry>
<term><command>max-zone-ttl</command></term>
<listitem>
<para>
- Specifies a maximum permissible TTL value in seconds.
- For convenience, TTL-style time unit suffixes may be
+ This specifies a maximum permissible TTL value in seconds.
+ For convenience, TTL-style time-unit suffixes may be
used to specify the maximum value.
When loading a zone file using a
<option>masterfile-format</option> of
<constant>text</constant> or <constant>raw</constant>,
any record encountered with a TTL higher than
- <option>max-zone-ttl</option> will cause the zone to
+ <option>max-zone-ttl</option> causes the zone to
be rejected.
</para>
<para>
rolling to a new DNSKEY, the old key needs to remain
available until RRSIG records have expired from
caches. The <option>max-zone-ttl</option> option guarantees
- that the largest TTL in the zone will be no higher
+ that the largest TTL in the zone is no higher
than the set value.
</para>
<para>
- (NOTE: Because <constant>map</constant>-format files
+ (Note: because <constant>map</constant>-format files
load directly into memory, this option cannot be
used with them.)
</para>
<listitem>
<para>
Zones configured for dynamic DNS may use this
- option to set the update method that will be used for
+ option to set the update method to be used for
the zone serial number in the SOA record.
</para>
<para>
With the default setting of
<command>serial-update-method increment;</command>, the
- SOA serial number will be incremented by one each time
+ SOA serial number is incremented by one each time
the zone is updated.
</para>
<para>
When set to
<command>serial-update-method unixtime;</command>, the
- SOA serial number will be set to the number of seconds
- since the UNIX epoch, unless the serial number is
+ SOA serial number is set to the number of seconds
+ since the Unix epoch, unless the serial number is
already greater than or equal to that value, in which
case it is simply incremented by one.
</para>
<para>
When set to
<command>serial-update-method date;</command>, the
- new SOA serial number will be the current date
+ new SOA serial number is the current date
in the form "YYYYMMDD", followed by two zeroes,
unless the existing serial number is already greater
than or equal to that value, in which case it is
<term><command>zone-statistics</command></term>
<listitem>
<para>
- If <userinput>full</userinput>, the server will collect
- statistical data on all zones (unless specifically
+ If <userinput>full</userinput>, the server collects
+ statistical data on all zones, unless specifically
turned off on a per-zone basis by specifying
<command>zone-statistics terse</command> or
<command>zone-statistics none</command>
- in the <command>zone</command> statement).
+ in the <command>zone</command> statement.
The default is <userinput>terse</userinput>, providing
minimal statistics on zones (including name and
current serial number, but not query type
These statistics may be accessed via the
<command>statistics-channel</command> or
using <command>rndc stats</command>, which
- will dump them to the file listed
+ dumps them to the file listed
in the <command>statistics-file</command>. See
also <xref linkend="statsfile"/>.
</para>
<listitem>
<para>
If <userinput>yes</userinput> and supported by the operating
- system, automatically rescan network interfaces when the
+ system, this automatically rescans network interfaces when the
interface addresses are added or removed. The default is
<userinput>yes</userinput>. This configuration option does
- not affect time based <command>interface-interval</command>
- option, and it is recommended to set the time based
+ not affect the time-based <command>interface-interval</command>
+ option; it is recommended to set the time-based
<command>interface-interval</command> to 0 when the operator
confirms that automatic interface scanning is supported by the
operating system.
</para>
<para>
The <command>automatic-interface-scan</command> implementation
- uses routing sockets for the network interface discovery,
- and therefore the operating system has to support the routing
+ uses routing sockets for the network interface discovery;
+ therefore, the operating system must support the routing
sockets for this feature to work.
</para>
</listitem>
cryptographic hash of the view name is used instead.
</para>
<para>
- Zones added at runtime will have their configuration
+ Configurations for zones added at runtime are
stored either in a new-zone file (NZF) or a new-zone
- database (NZD) depending on whether
+ database (NZD), depending on whether
<command>named</command> was linked with
liblmdb at compile time.
See <xref linkend="man.rndc"/> for further details
If <userinput>yes</userinput>, then the <command>AA</command> bit
is always set on NXDOMAIN responses, even if the server is
not actually
- authoritative. The default is <userinput>no</userinput>;
- this is
- a change from <acronym>BIND</acronym> 8. If you
- are using very old DNS software, you
- may need to set it to <userinput>yes</userinput>.
+ authoritative. The default is <userinput>no</userinput>.
</para>
</listitem>
</varlistentry>
<term><command>memstatistics</command></term>
<listitem>
<para>
- Write memory statistics to the file specified by
+ This writes memory statistics to the file specified by
<command>memstatistics-file</command> at exit.
The default is <userinput>no</userinput> unless
- '-m record' is specified on the command line in
+ <userinput>-m record</userinput> is specified on the command line, in
which case it is <userinput>yes</userinput>.
</para>
</listitem>
across
a dial-on-demand dialup link, which can be brought up by
traffic
- originating from this server. This has different effects
+ originating from this server. Although this setting has different effects
according
- to zone type and concentrates the zone maintenance so that
- it all
- happens in a short interval, once every <command>heartbeat-interval</command> and
- hopefully during the one call. It also suppresses some of
- the normal
+ to zone type, it concentrates the zone maintenance so that
+ everything
+ happens quickly, once every <command>heartbeat-interval</command>,
+ ideally during a single call. It also suppresses some
+ normal
zone maintenance traffic. The default is <userinput>no</userinput>.
</para>
<para>
- The <command>dialup</command> option
- may also be specified in the <command>view</command> and
- <command>zone</command> statements,
- in which case it overrides the global <command>dialup</command>
- option.
+ If specified in the <command>view</command> and
+ <command>zone</command> statements, the <command>dialup</command> option
+ overrides the global <command>dialup</command> option.
</para>
<para>
- If the zone is a master zone, then the server will send out a
+ If the zone is a primary zone, the server sends out a
NOTIFY
- request to all the slaves (default). This should trigger the
+ request to all the secondaries (default). This should trigger the
zone serial
- number check in the slave (providing it supports NOTIFY)
- allowing the slave
+ number check in the secondary (providing it supports NOTIFY),
+ allowing the secondary
to verify the zone while the connection is active.
The set of servers to which NOTIFY is sent can be controlled
by
</para>
<para>
If the
- zone is a slave or stub zone, then the server will suppress
+ zone is a secondary or stub zone, the server suppresses
the regular
- "zone up to date" (refresh) queries and only perform them
+ "zone up to date" (refresh) queries and only performs them
when the
- <command>heartbeat-interval</command> expires in
+ <command>heartbeat-interval</command> expires, in
addition to sending
NOTIFY requests.
</para>
<para>
Finer control can be achieved by using
- <userinput>notify</userinput> which only sends NOTIFY
- messages,
- <userinput>notify-passive</userinput> which sends NOTIFY
+ <userinput>notify</userinput>, which only sends NOTIFY
+ messages;
+ <userinput>notify-passive</userinput>, which sends NOTIFY
messages and
- suppresses the normal refresh queries, <userinput>refresh</userinput>
+ suppresses the normal refresh queries; <userinput>refresh</userinput>,
which suppresses normal refresh processing and sends refresh
queries
when the <command>heartbeat-interval</command>
- expires, and
- <userinput>passive</userinput> which just disables normal
+ expires; and
+ <userinput>passive</userinput>, which disables normal
refresh
processing.
</para>
In BIND 8, <userinput>fetch-glue yes</userinput>
caused the server to attempt to fetch glue resource records
it
- didn't have when constructing the additional
+ did not have when constructing the additional
data section of a response. This is now considered a bad
idea
and BIND 9 never does it.
<term><command>flush-zones-on-shutdown</command></term>
<listitem>
<para>
- When the nameserver exits due receiving SIGTERM,
+ When the nameserver exits upon receiving SIGTERM,
flush or do not flush any pending zone writes. The default
is
<command>flush-zones-on-shutdown</command> <userinput>no</userinput>.
In BIND 8, this enabled keeping of
statistics for every host that the name server interacts
with.
- Not implemented in BIND 9.
+ It is not implemented in BIND 9.
</para>
</listitem>
</varlistentry>
<term><command>root-key-sentinel</command></term>
<listitem>
<para>
- Respond to root key sentinel probes as described in
+ If <userinput>yes</userinput>, respond to root key sentinel probes as described in
draft-ietf-dnsop-kskroll-sentinel-08. The default is
<userinput>yes</userinput>.
</para>
It was used in <acronym>BIND</acronym> 8 to
determine whether a transaction log was
kept for Incremental Zone Transfer. <acronym>BIND</acronym> 9 maintains a transaction
- log whenever possible. If you need to disable outgoing
+ log whenever possible. To disable outgoing
incremental zone
transfers, use <command>provide-ixfr</command> <userinput>no</userinput>.
</para>
<para>
If <userinput>yes</userinput>, DNS name compression is
used in responses to regular queries (not including
- AXFR or IXFR, which always uses compression). Setting
+ AXFR or IXFR, which always use compression). Setting
this option to <userinput>no</userinput> reduces CPU
usage on servers and may improve throughput. However,
it increases response size, which may cause more queries
<listitem>
<para>
If set to <userinput>yes</userinput>, then when generating
- responses the server will only add records to the authority
+ responses the server only adds records to the authority
and additional data sections when they are required (e.g.
delegations, negative responses). This may improve the
performance of the server.
</para>
<para>
When set to <userinput>no-auth</userinput>, the
- server will omit records from the authority section
+ server omits records from the authority section
unless they are required, but it may still add
records to the additional section. When set to
<userinput>no-auth-recursive</userinput>, this
settings are useful when answering stub clients,
which usually ignore the authority section.
<userinput>no-auth-recursive</userinput> is
- designed for mixed-mode servers which handle
+ designed for mixed-mode servers that handle
both authoritative and recursive queries.
</para>
<para>
<term><command>minimal-any</command></term>
<listitem>
<para>
- If set to <userinput>yes</userinput>, then when
- generating a positive response to a query of type
- ANY over UDP, the server will reply with only one
+ If set to <userinput>yes</userinput>, the server replies with only one
of the RRsets for the query name, and its covering
- RRSIGs if any, instead of replying with all known
+ RRSIGs if any, when
+ generating a positive response to a query of type
+ ANY over UDP, instead of replying with all known
RRsets for the name. Similarly, a query for type
- RRSIG will be answered with the RRSIG records covering
+ RRSIG is answered with the RRSIG records covering
only one type. This can reduce the impact of some kinds
of attack traffic, without harming legitimate
clients. (Note, however, that the RRset returned is the
the smallest available RRset.)
Additionally, <option>minimal-responses</option> is
turned on for these queries, so no unnecessary records
- will be added to the authority or additional sections.
+ are added to the authority or additional sections.
The default is <userinput>no</userinput>.
</para>
</listitem>
<listitem>
<para>
This option was used in <acronym>BIND</acronym> 8 to allow
- a domain name to have multiple CNAME records in violation of
+ a domain name to have multiple CNAME records, in violation of
the DNS standards. <acronym>BIND</acronym> 9.2 onwards
- always strictly enforces the CNAME rules both in master
+ always strictly enforces the CNAME rules both in primary
files and dynamic updates.
</para>
</listitem>
If <userinput>yes</userinput> (the default),
DNS NOTIFY messages are sent when a zone the server is
authoritative for
- changes, see <xref linkend="notify"/>. The messages are
+ changes; see <xref linkend="notify"/>. The messages are
sent to the
- servers listed in the zone's NS records (except the master
+ servers listed in the zone's NS records (except the primary
server identified
in the SOA MNAME field), and to any servers listed in the
<command>also-notify</command> option.
<para>
If <userinput>master-only</userinput>, notifies are only
sent
- for master zones.
+ for primary zones.
If <userinput>explicit</userinput>, notifies are sent only
to
servers explicitly listed using <command>also-notify</command>.
statement,
in which case it overrides the <command>options notify</command> statement.
It would only be necessary to turn off this option if it
- caused slaves
+ caused secondary zones
to crash.
</para>
</listitem>
<term><command>notify-to-soa</command></term>
<listitem>
<para>
- If <userinput>yes</userinput> do not check the nameservers
+ If <userinput>yes</userinput>, do not check the name servers
in the NS RRset against the SOA MNAME. Normally a NOTIFY
- message is not sent to the SOA MNAME (SOA ORIGIN) as it is
- supposed to contain the name of the ultimate master.
- Sometimes, however, a slave is listed as the SOA MNAME in
- hidden master configurations and in that case you would
- want the ultimate master to still send NOTIFY messages to
- all the nameservers listed in the NS RRset.
+ message is not sent to the SOA MNAME (SOA ORIGIN), as it is
+ supposed to contain the name of the ultimate primary server.
+ Sometimes, however, a secondary server is listed as the SOA MNAME in
+ hidden primary configurations; in that case,
+ the ultimate primary should be set to still send NOTIFY messages to
+ all the name servers listed in the NS RRset.
</para>
</listitem>
</varlistentry>
<listitem>
<para>
If <userinput>yes</userinput>, and a
- DNS query requests recursion, then the server will attempt
+ DNS query requests recursion, then the server attempts
to do
all the work required to answer the query. If recursion is
off
- and the server does not already know the answer, it will
- return a
+ and the server does not already know the answer, it
+ returns a
referral response. The default is
<userinput>yes</userinput>.
Note that setting <command>recursion no</command> does not prevent
<term><command>require-server-cookie</command></term>
<listitem>
<para>
- Require a valid server cookie before sending a full
- response to a UDP request from a cookie aware client.
- BADCOOKIE is sent if there is a bad or no existent
+ If <userinput>yes</userinput>, require a valid server cookie before sending a full
+ response to a UDP request from a cookie-aware client.
+ BADCOOKIE is sent if there is a bad or nonexistent
server cookie.
The default is <userinput>no</userinput>.
</para>
<para>
- Set this to <userinput>yes</userinput> to test that DNS
- COOKIE clients correctly handle BADCOOKIE or if you are
+ Users wishing to test that DNS COOKIE clients correctly handle BADCOOKIE, or who are
getting a lot of forged DNS requests with DNS COOKIES
- present. Setting this to <userinput>yes</userinput> will
- result in reduced amplification effect in a reflection
- attack, as the BADCOOKIE response will be smaller than
+ present, should set this to <userinput>yes</userinput>.
+ Setting this to <userinput>yes</userinput>
+ results in a reduced amplification effect in a reflection
+ attack, as the BADCOOKIE response is smaller than
a full response, while also requiring a legitimate client
to follow up with a second query with the new, valid, cookie.
</para>
<listitem>
<para>
When set to the default value of <userinput>yes</userinput>,
- COOKIE EDNS options will be sent when applicable in
+ COOKIE EDNS options are sent when applicable in
replies to client queries. If set to
- <userinput>no</userinput>, COOKIE EDNS options will not
- be sent in replies. This can only be set at the global
+ <userinput>no</userinput>, COOKIE EDNS options are not
+ sent in replies. This can only be set at the global
options level, not per-view.
</para>
<para>
<para>
If <userinput>yes</userinput>, then a COOKIE EDNS
option is sent along with the query. If the
- resolver has previously talked to the server, the
+ resolver has previously communicated with the server, the
COOKIE returned in the previous transaction is sent.
This is used by the server to determine whether
the resolver has talked to it before. A resolver
<term><command>nocookie-udp-size</command></term>
<listitem>
<para>
- Sets the maximum size of UDP responses that will be
+ This sets the maximum size of UDP responses that are
sent to queries without a valid server COOKIE. A value
- below 128 will be silently raised to 128. The default
+ below 128 is silently raised to 128. The default
value is 4096, but the <command>max-udp-size</command>
option may further limit the response size.
</para>
<term><command>cookie-algorithm</command></term>
<listitem>
<para>
- Set the algorithm to be used when generating the
- server cookie. One of "aes", "sha1" or "sha256".
+ This sets the algorithm to be used when generating the
+ server cookie; the options are "aes", "sha1", or "sha256".
The default is "aes" if supported by the cryptographic
- library or otherwise "sha256".
+ library; otherwise, "sha256".
</para>
</listitem>
</varlistentry>
If set, this is a shared secret used for generating
and verifying EDNS COOKIE options
within an anycast cluster. If not set, the system
- will generate a random secret at startup. The
+ generates a random secret at startup. The
shared secret is encoded as a hex string and needs
- to be 128 bits for AES128, 160 bits for SHA1 and
+ to be 128 bits for AES128, 160 bits for SHA1, and
256 bits for SHA256.
</para>
<para>
If there are multiple secrets specified, the first
one listed in <filename>named.conf</filename> is
used to generate new server cookies. The others
- will only be used to verify returned cookies.
+ are only used to verify returned cookies.
</para>
</listitem>
</varlistentry>
<term><command>rfc2308-type1</command></term>
<listitem>
<para>
- Setting this to <userinput>yes</userinput> will
- cause the server to send NS records along with the SOA
+ Setting this to <userinput>yes</userinput>
+ causes the server to send NS records along with the SOA
record for negative
answers. The default is <userinput>no</userinput>.
</para>
<note>
<simpara>
-
Not yet implemented in <acronym>BIND</acronym>
+
This is not yet implemented in <acronym>BIND</acronym>
9.
</simpara>
</note>
<term><command>trust-anchor-telemetry</command></term>
<listitem>
<para>
- Causes <command>named</command> to send specially-formed
+ This causes <command>named</command> to send specially formed
queries once per day to domains for which trust anchors
have been configured via <command>trusted-keys</command>,
<command>managed-keys</command>, or
to largest prior to encoding. The query type is NULL.
</para>
<para>
- By monitoring these queries, zone operators will
- be able to see which resolvers have been updated to
+ By monitoring these queries, zone operators are
+ able to see which resolvers have been updated to
trust a new key; this may help them decide when it
is safe to remove an old one.
</para>
<listitem>
<para>
<emphasis>This option is obsolete</emphasis>.
- If you need to disable IXFR to a particular server or
+ To disable IXFR to a particular server or
servers, see
the information on the <command>provide-ixfr</command> option
in <xref linkend="server_statement_definition_and_usage"/>.
8 to make
the server treat carriage return ("<command>\r</command>") characters the same way
as a space or tab character,
- to facilitate loading of zone files on a UNIX system that
+ to facilitate loading of zone files on a Unix system that
were generated
on an NT or DOS machine. In <acronym>BIND</acronym> 9, both UNIX "<command>\n</command>"
and NT/DOS "<command>\r\n</command>" newlines
query is being answered from authoritative data (a zone
configured into the server), the additional data section of
the
- reply will be filled in using data from other authoritative
+ reply is filled in using data from other authoritative
zones
and from the cache. In some situations this is undesirable,
such
as when there is concern over the correctness of the cache,
or
- in servers where slave zones may be added and modified by
+ in servers where secondary zones may be added and modified by
untrusted third parties. Also, avoiding
- the search for this additional data will speed up server
+ the search for this additional data speeds up server
operations
at the possible expense of additional queries to resolve
what would
<para>
For example, if a query asks for an MX record for host <literal>foo.example.com</literal>,
and the record found is "<literal>MX 10 mail.example.net</literal>", normally the address
- records (A and AAAA) for <literal>mail.example.net</literal> will be provided as well,
+ records (A and AAAA) for <literal>mail.example.net</literal> are provided as well,
if known, even though they are not in the example.com zone.
Setting these options to <command>no</command>
disables this behavior and makes
some other
known parent of the query name. Since the data in an
upwards referral
- comes from the cache, the server will not be able to provide
+ comes from the cache, the server is not able to provide
upwards
referrals when <command>additional-from-cache no</command>
- has been specified. Instead, it will respond to such
+ has been specified. Instead, it responds to such
queries
with REFUSED. This should not cause any problems since
upwards referrals are not required for the resolution
<listitem>
<para>
If <userinput>yes</userinput>, then an
- IPv4-mapped IPv6 address will match any address match
+ IPv4-mapped IPv6 address matches any address-match
list entries that match the corresponding IPv4 address.
</para>
<para>
This option was introduced to work around a kernel quirk
in some operating systems that causes IPv4 TCP
connections, such as zone transfers, to be accepted on an
- IPv6 socket using mapped addresses. This caused address
- match lists designed for IPv4 to fail to match. However,
+ IPv6 socket using mapped addresses. This caused address-match
+ lists designed for IPv4 to fail to match. However,
<command>named</command> now solves this problem
internally. The use of this option is discouraged.
</para>
<para>
If <userinput>break-dnssec</userinput>,
then AAAA records are deleted even when DNSSEC is enabled.
- As suggested by the name, this makes the response not verify,
- because the DNSSEC protocol is designed detect deletions.
+ As suggested by the name, this causes the response to not verify,
+ because the DNSSEC protocol is designed to detect deletions.
</para>
<para>
This mechanism can erroneously cause other servers to
not give AAAA records to their clients.
- A recursing server with both IPv6 and IPv4 network connections
+ A recursing server with both IPv6 and IPv4 network connections,
that queries an authoritative server using this mechanism
- via IPv4 will be denied AAAA records even if its client is
+ via IPv4, is denied AAAA records even if its client is
using IPv6.
</para>
<para>
<term><command>filter-aaaa-on-v6</command></term>
<listitem>
<para>
- Identical to <command>filter-aaaa-on-v4</command>,
+ This is identical to <command>filter-aaaa-on-v4</command>,
except it filters AAAA responses to queries from IPv6
clients instead of IPv4 clients. To filter all
responses, set both options to <userinput>yes</userinput>.
<listitem>
<para>
When <userinput>yes</userinput> and the server loads a new
- version of a master zone from its zone file or receives a
- new version of a slave file via zone transfer, it will
- compare the new version to the previous one and calculate
+ version of a primary zone from its zone file or receives a
+ new version of a secondary file via zone transfer, it
+ compares the new version to the previous one and calculates
a set of differences. The differences are then logged in
- the zone's journal file such that the changes can be
- transmitted to downstream slaves as an incremental zone
+ the zone's journal file so that the changes can be
+ transmitted to downstream secondaries as an incremental zone
transfer.
</para>
<para>
By allowing incremental zone transfers to be used for
non-dynamic zones, this option saves bandwidth at the
expense of increased CPU and memory consumption at the
- master.
+ primary server.
In particular, if the new version of a zone is completely
different from the previous one, the set of differences
- will be of a size comparable to the combined size of the
- old and new zone version, and the server will need to
+ is of a size comparable to the combined size of the
+ old and new zone versions, and the server needs to
temporarily allocate memory to hold this complete
difference set.
</para>
<para><command>ixfr-from-differences</command>
also accepts <command>master</command> and
<command>slave</command> at the view and options
- levels which causes
+ levels, which causes
<command>ixfr-from-differences</command> to be enabled for
- all <command>master</command> or
- <command>slave</command> zones respectively.
+ all primary or secondary zones, respectively.
It is off by default.
</para>
<para>
<term><command>multi-master</command></term>
<listitem>
<para>
- This should be set when you have multiple masters for a zone
+ This should be set when there are multiple primary servers for a zone
and the
- addresses refer to different machines. If <userinput>yes</userinput>, <command>named</command> will
+ addresses refer to different machines. If <userinput>yes</userinput>, <command>named</command> does
not log
- when the serial number on the master is less than what <command>named</command>
+ when the serial number on the primary is less than what <command>named</command>
currently
has. The default is <userinput>no</userinput>.
</para>
<para>
<command>auto-dnssec maintain;</command> includes the
above, but also automatically adjusts the zone's DNSSEC
- keys on schedule, according to the keys' timing metadata
+ keys on a schedule, according to the keys' timing metadata
(see <xref linkend="man.dnssec-keygen"/> and
<xref linkend="man.dnssec-settime"/>). The command
<command>rndc sign
repository and schedule key maintenance events to occur
in the future, but it does not sign the full zone
immediately. Note: once keys have been loaded for a
- zone the first time, the repository will be searched
+ zone the first time, the repository is searched
for changes periodically, regardless of whether
<command>rndc loadkeys</command> is used. The recheck
interval is defined by
This indicates whether DNSSEC-related resource
records are to be returned by <command>named</command>.
If set to <userinput>no</userinput>,
- <command>named</command> will not return DNSSEC-related
+ <command>named</command> does not return DNSSEC-related
resource records unless specifically queried for.
The default is <userinput>yes</userinput>.
</para>
<term><command>dnssec-validation</command></term>
<listitem>
<para>
- Enable DNSSEC validation in <command>named</command>.
- Note <command>dnssec-enable</command> also needs to be
+ This option enables DNSSEC validation in <command>named</command>.
+ Note that <command>dnssec-enable</command> also needs to be
set to <userinput>yes</userinput> to be effective.
If set to <userinput>no</userinput>, DNSSEC validation
is disabled.
</para>
<para>
If set to <userinput>auto</userinput>, DNSSEC validation
- is enabled, and a default trust anchor for the DNS root
+ is enabled and a default trust anchor for the DNS root
zone is used. If set to <userinput>yes</userinput>,
DNSSEC validation is enabled, but a trust anchor must be
manually configured using a <command>trusted-keys</command>
<para>
The default root trust anchor is stored in the file
<filename>bind.keys</filename>.
- <command>named</command> will load that key at
+ <command>named</command> loads that key at
startup if <command>dnssec-validation</command> is
set to <constant>auto</constant>. A copy of the file is
installed along with BIND 9, and is current as of the
from <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.isc.org/bind-keys">https://www.isc.org/bind-keys</link>.
</para>
<para>
- To prevent problems if <filename>bind.keys</filename> is
+ (To prevent problems if <filename>bind.keys</filename> is
not found, the current trust anchor is also compiled in
to <command>named</command>. Relying on this is not
recommended, however, as it requires <command>named</command>
</para>
<note>
<para>
- <command>named</command> <emphasis>only</emphasis>
- loads the root key from <filename>bind.keys</filename>.
+ <command>named</command> loads <emphasis>only</emphasis>
+ the root key from <filename>bind.keys</filename>.
The file cannot be used to store keys for other zones.
The root key in <filename>bind.keys</filename> is ignored
if <command>dnssec-validation auto</command> is not in
<para>
Whenever the resolver sends out queries to an
EDNS-compliant server, it always sets the DO bit
- indicating it can support DNSSEC responses even if
+ indicating it can support DNSSEC responses, even if
<command>dnssec-validation</command> is off.
</para>
</note>
<term><command>dnssec-accept-expired</command></term>
<listitem>
<para>
- Accept expired signatures when verifying DNSSEC signatures.
+ This accepts expired signatures when verifying DNSSEC signatures.
The default is <userinput>no</userinput>.
Setting this option to <userinput>yes</userinput>
leaves <command>named</command> vulnerable to
Query logging provides a complete log of all incoming
queries and all query errors. This provides more insight
into the server's activity, but with a cost to
- performance which may be significant on heavily-loaded
+ performance which may be significant on heavily loaded
servers.
</para>
<para>
<para>
This option is used to restrict the character set and syntax
of
- certain domain names in master files and/or DNS responses
+ certain domain names in zone files and/or DNS responses
received
from the network. The default varies according to usage
- area. For
- <command>master</command> zones the default is <command>fail</command>.
- For <command>slave</command> zones the default
- is <command>warn</command>.
- For answers received from the network (<command>response</command>)
+ area. For primary zones (i.e.,
+ <command>type master</command>),
+ the default is <command>fail</command>.
+ For secondary zones (<command>type slave</command>), the
+ default is <command>warn</command>.
+ For answers received from the network (<command>response</command>),
the default is <command>ignore</command>.
</para>
<para>
from RFC 952 and RFC 821 as modified by RFC 1123.
</para>
<para><command>check-names</command>
- applies to the owner names of A, AAAA and MX records.
+ applies to the owner names of A, AAAA, and MX records.
It also applies to the domain names in the RDATA of NS, SOA,
MX, and SRV records.
- It also applies to the RDATA of PTR records where the owner
- name indicated that it is a reverse lookup of a hostname
+ It further applies to the RDATA of PTR records where the owner
+ name indicates that it is a reverse lookup of a hostname
(the owner name ends in IN-ADDR.ARPA, IP6.ARPA, or IP6.INT).
</para>
</listitem>
<term><command>check-dup-records</command></term>
<listitem>
<para>
- Check master zones for records that are treated as different
+ This checks primary zones for records that are treated as different
by DNSSEC but are semantically equal in plain DNS. The
default is to <command>warn</command>. Other possible
values are <command>fail</command> and
<term><command>check-mx</command></term>
<listitem>
<para>
- Check whether the MX record appears to refer to a IP address.
+ This checks whether the MX record appears to refer to a IP address.
The default is to <command>warn</command>. Other possible
values are <command>fail</command> and
<command>ignore</command>.
result of a failure
to understand the wildcard matching algorithm (RFC 1034).
This option
- affects master zones. The default (<command>yes</command>) is to check
+ affects primary zones. The default (<command>yes</command>) is to check
for non-terminal wildcards and issue a warning.
</para>
</listitem>
<term><command>check-integrity</command></term>
<listitem>
<para>
- Perform post load zone integrity checks on master
- zones. This checks that MX and SRV records refer
+ This performs post-load zone integrity checks on primary
+ zones. It checks that MX and SRV records refer
to address (A or AAAA) records and that glue
address records exist for delegated zones. For
- MX and SRV records only in-zone hostnames are
- checked (for out-of-zone hostnames use
+ MX and SRV records, only in-zone hostnames are
+ checked (for out-of-zone hostnames, use
<command>named-checkzone</command>).
- For NS records only names below top of zone are
+ For NS records, only names below top-of-zone are
checked (for out-of-zone names and glue consistency
- checks use <command>named-checkzone</command>).
+ checks, use <command>named-checkzone</command>).
The default is <command>yes</command>.
</para>
<para>
- The use of the SPF record for publishing Sender
- Policy Framework is deprecated as the migration
+ The use of the SPF record to publish Sender
+ Policy Framework is deprecated, as the migration
from using TXT records to SPF records was abandoned.
Enabling this option also checks that a TXT Sender
Policy Framework record exists (starts with "v=spf1")
if there is an SPF record. Warnings are emitted if the
- TXT record does not exist and can be suppressed with
+ TXT record does not exist; they can be suppressed with
<command>check-spf</command>.
</para>
</listitem>
<term><command>check-mx-cname</command></term>
<listitem>
<para>
- If <command>check-integrity</command> is set then
- fail, warn or ignore MX records that refer
+ If <command>check-integrity</command> is set, then
+ fail, warn, or ignore MX records that refer
to CNAMES. The default is to <command>warn</command>.
</para>
</listitem>
<term><command>check-srv-cname</command></term>
<listitem>
<para>
- If <command>check-integrity</command> is set then
- fail, warn or ignore SRV records that refer
+ If <command>check-integrity</command> is set, then
+ fail, warn, or ignore SRV records that refer
to CNAMES. The default is to <command>warn</command>.
</para>
</listitem>
<term><command>check-spf</command></term>
<listitem>
<para>
- If <command>check-integrity</command> is set then
+ If <command>check-integrity</command> is set,
check that there is a TXT Sender Policy Framework
record present (starts with "v=spf1") if there is an
SPF record present. The default is
<term><command>zero-no-soa-ttl</command></term>
<listitem>
<para>
- When returning authoritative negative responses to
- SOA queries set the TTL of the SOA record returned in
+ If <userinput>yes</userinput>, when returning authoritative negative responses to
+ SOA queries, set the TTL of the SOA record returned in
the authority section to zero.
The default is <command>yes</command>.
</para>
<term><command>zero-no-soa-ttl-cache</command></term>
<listitem>
<para>
- When caching a negative response to a SOA query
+ If <userinput>yes</userinput>, when caching a negative response to an SOA query
set the TTL to zero.
The default is <command>no</command>.
</para>
then the KSK bit is ignored; KSKs are treated as if they
were ZSKs and are used to sign the entire zone. This is
similar to the <command>dnssec-signzone -z</command>
- command line option.
+ command-line option.
</para>
<para>
When this option is set to <literal>yes</literal>, there
must be at least two active keys for every algorithm
represented in the DNSKEY RRset: at least one KSK and one
ZSK per algorithm. If there is any algorithm for which
- this requirement is not met, this option will be ignored
+ this requirement is not met, this option is ignored
for that algorithm.
</para>
</listitem>
<para>
When this option and <command>update-check-ksk</command>
are both set to <literal>yes</literal>, only key-signing
- keys (that is, keys with the KSK bit set) will be used
+ keys (that is, keys with the KSK bit set) are used
to sign the DNSKEY RRset at the zone apex. Zone-signing
- keys (keys without the KSK bit set) will be used to sign
+ keys (keys without the KSK bit set) are used to sign
the remainder of the zone, but not the DNSKEY RRset.
This is similar to the
- <command>dnssec-signzone -x</command> command line option.
+ <command>dnssec-signzone -x</command> command-line option.
</para>
<para>
The default is <command>no</command>. If
<term><command>try-tcp-refresh</command></term>
<listitem>
<para>
- Try to refresh the zone using TCP if UDP queries fail.
- For BIND 8 compatibility, the default is
+ If <userinput>yes</userinput>, try to refresh the zone using TCP if UDP queries fail.
+ The default is
<command>yes</command>.
</para>
</listitem>
<term><command>dnssec-secure-to-insecure</command></term>
<listitem>
<para>
- Allow a dynamic zone to transition from secure to
+ This allows a dynamic zone to transition from secure to
insecure (i.e., signed to unsigned) by deleting all
of the DNSKEY records. The default is <command>no</command>.
If set to <command>yes</command>, and if the DNSKEY RRset
at the zone apex is deleted, all RRSIG and NSEC records
- will be removed from the zone as well.
+ are removed from the zone as well.
</para>
<para>
- If the zone uses NSEC3, then it is also necessary to
- delete the NSEC3PARAM RRset from the zone apex; this will
- cause the removal of all corresponding NSEC3 records.
+ If the zone uses NSEC3, it is also necessary to
+ delete the NSEC3PARAM RRset from the zone apex; this
+ causes the removal of all corresponding NSEC3 records.
(It is expected that this requirement will be eliminated
in a future release.)
</para>
<listitem>
<para>
This option is only meaningful if the
- forwarders list is not empty. A value of <varname>first</varname>,
- the default, causes the server to query the forwarders
- first — and
- if that doesn't answer the question, the server will then
- look for
+ forwarders list is not empty. A value of <varname>first</varname> is
+ the default and causes the server to query the forwarders
+ first;
+ if that does not answer the question, the server then
+ looks for
the answer itself. If <varname>only</varname> is
specified, the
- server will only query the forwarders.
+ server only queries the forwarders.
</para>
</listitem>
</varlistentry>
<term><command>forwarders</command></term>
<listitem>
<para>
- Specifies a list of IP addresses to which queries shall be
+ This specifies a list of IP addresses to which queries are
forwarded. The default is the empty list (no forwarding).
Each address in the list can be associated with an optional
port number and/or DSCP value, and a default port number and
<para>
Forwarding can also be configured on a per-domain basis, allowing
for the global forwarding options to be overridden in a variety
- of ways. You can set particular domains to use different
+ of ways. Particular domains can be set to use different
forwarders,
or have a different <command>forward only/first</command> behavior,
- or not forward at all, see <xref linkend="zone_statement_grammar"/>.
+ or not forward at all; see <xref linkend="zone_statement_grammar"/>.
</para>
</section>
<section xml:id="dual_stack"><info><title>Dual-stack Servers</title></info>
<para>
- Dual-stack servers are used as servers of last resort to work
+ Dual-stack servers are used as servers of last resort, to work
around
problems in reachability due the lack of support for either IPv4
or IPv6
<term><command>dual-stack-servers</command></term>
<listitem>
<para>
- Specifies host names or addresses of machines with access to
+ This specifies host names or addresses of machines with access to
both IPv4 and IPv6 transports. If a hostname is used, the
server must be able
to resolve the name using only the transport it has. If the
- machine is dual
- stacked, then the <command>dual-stack-servers</command> have no effect unless
+ machine is dual-stacked, the <command>dual-stack-servers</command> parameter has no effect unless
access to a transport has been disabled on the command line
- (e.g. <command>named -4</command>).
+ (e.g., <command>named -4</command>).
</para>
</listitem>
</varlistentry>
<term><command>allow-notify</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to
- notify this server, a slave, of zone changes in addition
- to the zone masters.
+ This ACL specifies which hosts are allowed to
+ notify this secondary server of zone changes in addition
+ to the zone primaries.
<command>allow-notify</command> may also be
specified in the
<command>zone</command> statement, in which case
it overrides the
<command>options allow-notify</command>
statement. It is only meaningful
- for a slave zone. If not specified, the default is to
+ for a secondary zone. If not specified, the default is to
process notify messages
- only from a zone's master.
+ only from a zone's primary.
</para>
</listitem>
</varlistentry>
<term><command>allow-query</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to ask ordinary
+ This specifies which hosts are allowed to ask ordinary
DNS questions. <command>allow-query</command> may
also be specified in the <command>zone</command>
statement, in which case it overrides the
</para>
<note>
<para>
- <command>allow-query-cache</command> is now
+ <command>allow-query-cache</command> is
used to specify access to the cache.
</para>
</note>
<term><command>allow-query-on</command></term>
<listitem>
<para>
- Specifies which local addresses can accept ordinary
+ This specifies which local addresses can accept ordinary
DNS questions. This makes it possible, for instance,
to allow queries on internal-facing interfaces but
disallow them on external-facing ones, without
Note that <command>allow-query-on</command> is only
checked for queries that are permitted by
<command>allow-query</command>. A query must be
- allowed by both ACLs, or it will be refused.
+ allowed by both ACLs, or it is refused.
</para>
<para>
<command>allow-query-on</command> may
<term><command>allow-query-cache</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to get answers
+ This specifies which hosts are allowed to get answers
from the cache. If <command>allow-query-cache</command>
- is not set then <command>allow-recursion</command>
- is used if set, otherwise <command>allow-query</command>
- is used if set unless <command>recursion no;</command> is
- set in which case <command>none;</command> is used,
- otherwise the default (<command>localnets;</command>
+ is not set, BIND checks to see if the following parameters
+ are set, in order: <command>allow-recursion</command> and
+ <command>allow-query</command>
+ (unless <command>recursion no;</command> is
+ set, in which case <command>none;</command> is used).
+ If neither of those parameters is set, the default (<command>localnets;</command>
<command>localhost;</command>) is used.
</para>
</listitem>
<term><command>allow-query-cache-on</command></term>
<listitem>
<para>
- Specifies which local addresses can give answers
+ This specifies which local addresses can send answers
from the cache. If not specified, the default is
to allow cache queries on any address,
- <command>localnets</command> and
+ <command>localnets</command>, and
<command>localhost</command>.
</para>
</listitem>
<term><command>allow-recursion</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to make recursive
- queries through this server. If
- <command>allow-recursion</command> is not set
- then <command>allow-query-cache</command> is
- used if set, otherwise <command>allow-query</command>
- is used if set, otherwise the default
+ This specifies which hosts are allowed to make recursive
+ queries through this server. BIND checks to see if the
+ following parameters are set, in order:
+ <command>allow-recursion</command>, <command>allow-query-cache</command>,
+ and <command>allow-query</command>.
+ If none of those parameters are set, the default
(<command>localnets;</command>
<command>localhost;</command>) is used.
</para>
<term><command>allow-recursion-on</command></term>
<listitem>
<para>
- Specifies which local addresses can accept recursive
+ This specifies which local addresses can accept recursive
queries. If not specified, the default is to allow
recursive queries on all addresses.
</para>
<term><command>allow-update</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to
- submit Dynamic DNS updates for master zones. The default is
+ This specifies which hosts are allowed to
+ submit Dynamic DNS updates for primary zones. The default is
to deny
updates from all hosts. Note that allowing updates based
on the requestor's IP address is insecure; see
<term><command>allow-update-forwarding</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to
- submit Dynamic DNS updates to slave zones to be forwarded to
+ This specifies which hosts are allowed to
+ submit Dynamic DNS updates to secondary zones to be forwarded to
the
- master. The default is <userinput>{ none; }</userinput>,
+ primary. The default is <userinput>{ none; }</userinput>,
which
- means that no update forwarding will be performed. To
+ means that no update forwarding is performed. To
enable
update forwarding, specify
<userinput>allow-update-forwarding { any; };</userinput>.
Specifying values other than <userinput>{ none; }</userinput> or
<userinput>{ any; }</userinput> is usually
- counterproductive, since
+ counterproductive;
the responsibility for update access control should rest
with the
- master server, not the slaves.
+ primary server, not the secondaries.
</para>
<para>
- Note that enabling the update forwarding feature on a slave
+ Note that enabling the update forwarding feature on a secondary
server
- may expose master servers relying on insecure IP address
- based
- access control to attacks; see <xref linkend="dynamic_update_security"/>
+ may expose primary servers to attacks if they rely on insecure
+ IP-address-based
+ access control; see <xref linkend="dynamic_update_security"/>
for more details.
</para>
</listitem>
<term><command>allow-transfer</command></term>
<listitem>
<para>
- Specifies which hosts are allowed to
+ This specifies which hosts are allowed to
receive zone transfers from the server. <command>allow-transfer</command> may
also be specified in the <command>zone</command>
statement, in which
<term><command>blackhole</command></term>
<listitem>
<para>
- Specifies a list of addresses that the
- server will not accept queries from or use to resolve a
+ This specifies a list of addresses which the
+ server does accept queries from or use to resolve a
query. Queries
- from these addresses will not be responded to. The default
+ from these addresses are not responded to. The default
is <userinput>none</userinput>.
</para>
</listitem>
<term><command>filter-aaaa</command></term>
<listitem>
<para>
- Specifies a list of addresses to which
+ This specifies a list of addresses to which
<command>filter-aaaa-on-v4</command>
and <command>filter-aaaa-on-v6</command>
apply. The default is <userinput>any</userinput>.
<term><command>keep-response-order</command></term>
<listitem>
<para>
- Specifies a list of addresses to which the server
- will send responses to TCP queries in the same order
+ This specifies a list of addresses to which the server
+ sends responses to TCP queries, in the same order
in which they were received. This disables the
processing of TCP queries in parallel. The default
is <userinput>none</userinput>.
<varlistentry>
<term><command>no-case-compress</command></term> <listitem>
<para>
- Specifies a list of addresses which require responses
+ This specifies a list of addresses which require responses
to use case-insensitive compression. This ACL can be
used when <command>named</command> needs to work with
clients that do not comply with the requirement in RFC
<para>
If left undefined, the ACL defaults to
<command>none</command>: case-insensitive compression
- will be used for all clients. If the ACL is defined and
- matches a client, then case will be ignored when
+ is used for all clients. If the ACL is defined and
+ matches a client, case is ignored when
compressing domain names in DNS responses sent to that
client.
</para>
<para>
- This can result in slightly smaller responses: if
+ This can result in slightly smaller responses; if
a response contains the names "example.com" and
- "example.COM", case-insensitive compression would treat
+ "example.COM", case-insensitive compression treats
the second one as a duplicate. It also ensures
that the case of the query name exactly matches the
case of the owner names of returned records, rather
- than matching the case of the records entered in
+ than matches the case of the records entered in
the zone file. This allows responses to exactly
match the query, which is required by some clients
due to incorrect use of case-sensitive comparisons.
</para>
<para>
There are circumstances in which <command>named</command>
- will not preserve the case of owner names of records:
+ does not preserve the case of owner names of records:
if a zone file defines records of different types with
the same name, but the capitalization of the name is
different (e.g., "www.example.com/A" and
"WWW.EXAMPLE.COM/AAAA"), then all responses for that
- name will use the <emphasis>first</emphasis> version
+ name use the <emphasis>first</emphasis> version
of the name that was used in the zone file. This
limitation may be addressed in a future release. However,
domain names specified in the rdata of resource records
- (i.e., records of type NS, MX, CNAME, etc) will always
+ (i.e., records of type NS, MX, CNAME, etc.) always
have their case preserved unless the client matches this
ACL.
</para>
<term><command>resolver-query-timeout</command></term>
<listitem>
<para>
- The amount of time in seconds that the resolver
- will spend attempting to resolve a recursive
+ This is the amount of time in seconds that the
+ resolver spends attempting to resolve a recursive
query before failing. The default and minimum
is <literal>10</literal> and the maximum is
<literal>30</literal>. Setting it to
- <literal>0</literal> will result in the default
+ <literal>0</literal> results in the default
being used.
</para>
</listitem>
<section xml:id="interfaces"><info><title>Interfaces</title></info>
<para>
- The interfaces and ports that the server will answer queries
+ The interfaces and ports that the server answers queries
from may be specified using the <command>listen-on</command> option. <command>listen-on</command> takes
an optional port and an <varname>address_match_list</varname>
of IPv4 addresses. (IPv6 addresses are ignored, with a
logged warning.)
- The server will listen on all interfaces allowed by the address
- match list. If a port is not specified, port 53 will be used.
+ The server listens on all interfaces allowed by the address
+ match list. If a port is not specified, port 53 is used.
</para>
<para>
Multiple <command>listen-on</command> statements are
allowed.
- For example,
+ For example:
</para>
<programlisting>listen-on { 5.6.7.8; };
</programlisting>
<para>
- will enable the name server on port 53 for the IP address
+ enables the name server on port 53 for the IP address
5.6.7.8, and on port 1234 of an address on the machine in net
1.2 that is not 1.2.3.4.
</para>
<para>
If no <command>listen-on</command> is specified, the
- server will listen on port 53 on all IPv4 interfaces.
+ server listens on port 53 on all IPv4 interfaces.
</para>
<para>
The <command>listen-on-v6</command> option is used to
- specify the interfaces and the ports on which the server will
- listen for incoming queries sent using IPv6. If not specified,
- the server will listen on port 53 on all IPv6 interfaces.
+ specify the interfaces and the ports on which the server
+ listens for incoming queries sent using IPv6. If not specified,
+ the server listens on port 53 on all IPv6 interfaces.
</para>
<para>
as the <varname>address_match_list</varname> for the
<command>listen-on-v6</command> option,
the server does not bind a separate socket to each IPv6 interface
- address as it does for IPv4 if the operating system has enough API
- support for IPv6 (specifically if it conforms to RFC 3493 and RFC
+ address as it does for IPv4, if the operating system has enough API
+ support for IPv6 (specifically, if it conforms to RFC 3493 and RFC
3542).
Instead, it listens on the IPv6 wildcard address.
If the system only has incomplete API support for IPv6, however,
address,
regardless of whether the desired API is supported by the system.
IPv4 addresses specified in <command>listen-on-v6</command>
- will be ignored, with a logged warning.
+ are ignored, with a logged warning.
</para>
<para>
Multiple <command>listen-on-v6</command> options can
be used.
- For example,
+ For example:
</para>
<programlisting>listen-on-v6 { any; };
</programlisting>
<para>
- will enable the name server on port 53 for any IPv6 addresses
+ enables the name server on port 53 for any IPv6 addresses
(with a single wildcard socket),
- and on port 1234 of IPv6 addresses that is not in the prefix
- 2001:db8::/32 (with separate sockets for each matched address.)
+ and on port 1234 of IPv6 addresses that are not in the prefix
+ 2001:db8::/32 (with separate sockets for each matched address).
</para>
<para>
- To make the server not listen on any IPv6 address, use
+ To instruct the server not to listen on any IPv6 address, use:
</para>
<programlisting>listen-on-v6 { none; };
<section xml:id="query_address"><info><title>Query Address</title></info>
<para>
- If the server doesn't know the answer to a question, it will
- query other name servers. <command>query-source</command> specifies
+ If the server does not know the answer to a question, it
+ queries other name servers. <command>query-source</command> specifies
the address and port used for such queries. For queries sent over
IPv6, there is a separate <command>query-source-v6</command> option.
If <command>address</command> is <command>*</command> (asterisk) or is omitted,
a wildcard IP address (<command>INADDR_ANY</command>)
- will be used.
+ is used.
</para>
<para>
If <command>port</command> is <command>*</command> or is omitted,
a random port number from a pre-configured
- range is picked up and will be used for each query.
- The port range(s) is that specified in
+ range is picked up and used for each query.
+ The port range(s) is specified in
the <command>use-v4-udp-ports</command> (for IPv4)
and <command>use-v6-udp-ports</command> (for IPv6)
options, excluding the ranges specified in
<para>
If <command>use-v4-udp-ports</command> or
<command>use-v6-udp-ports</command> is unspecified,
- <command>named</command> will check if the operating
+ <command>named</command> checks whether the operating
system provides a programming interface to retrieve the
system's default range for ephemeral ports.
If such an interface is available,
- <command>named</command> will use the corresponding system
- default range; otherwise, it will use its own defaults:
+ <command>named</command> uses the corresponding system
+ default range; otherwise, it uses its own defaults:
</para>
<programlisting>use-v4-udp-ports { range 1024 65535; };
</programlisting>
<para>
- Note: make sure the ranges be sufficiently large for
- security. A desirable size depends on various parameters,
+ Note: make sure the ranges are sufficiently large for
+ security. A desirable size depends on several parameters,
but we generally recommend it contain at least 16384 ports
(14 bits of entropy).
Note also that the system's default range when used may be
too small for this purpose, and that the range may even be
changed while <command>named</command> is running; the new
- range will automatically be applied when <command>named</command>
+ range is automatically applied when <command>named</command>
is reloaded.
- It is encouraged to
- configure <command>use-v4-udp-ports</command> and
- <command>use-v6-udp-ports</command> explicitly so that the
+ Explicit
+ configuration of <command>use-v4-udp-ports</command> and
+ <command>use-v6-udp-ports</command> is encouraged, so that the
ranges are sufficiently large and are reasonably
independent from the ranges used by other applications.
</para>
<para>
Note: the operational configuration
where <command>named</command> runs may prohibit the use
- of some ports. For example, UNIX systems will not allow
- <command>named</command> running without a root privilege
+ of some ports. For example, Unix systems do not allow
+ <command>named</command>, if run without root privilege,
to use ports less than 1024.
If such ports are included in the specified (or detected)
set of query ports, the corresponding query attempts will
<term><command>also-notify</command></term>
<listitem>
<para>
- Defines a global list of IP addresses of name servers
+ This option defines a global list of IP addresses of name servers
that are also sent NOTIFY messages whenever a fresh copy of
the
zone is loaded, in addition to the servers listed in the
zone's NS records.
- This helps to ensure that copies of the zones will
+ This helps to ensure that copies of the zones
quickly converge on stealth servers.
Optionally, a port may be specified with each
<command>also-notify</command> address to send
<para>
If an <command>also-notify</command> list
is given in a <command>zone</command> statement,
- it will override
+ it overrides
the <command>options also-notify</command>
statement. When a <command>zone notify</command>
statement
is set to <command>no</command>, the IP
- addresses in the global <command>also-notify</command> list will
- not be sent NOTIFY messages for that zone. The default is
+ addresses in the global <command>also-notify</command> list are
+ not sent NOTIFY messages for that zone. The default is
the empty
list (no global notification list).
</para>
<listitem>
<para>
Inbound zone transfers running longer than
- this many minutes will be terminated. The default is 120
+ this many minutes are terminated. The default is 120
minutes
(2 hours). The maximum value is 28 days (40320 minutes).
</para>
<listitem>
<para>
Inbound zone transfers making no progress
- in this many minutes will be terminated. The default is 60
+ in this many minutes are terminated. The default is 60
minutes
(1 hour). The maximum value is 28 days (40320 minutes).
</para>
<listitem>
<para>
Outbound zone transfers running longer than
- this many minutes will be terminated. The default is 120
+ this many minutes are terminated. The default is 120
minutes
(2 hours). The maximum value is 28 days (40320 minutes).
</para>
<listitem>
<para>
Outbound zone transfers making no progress
- in this many minutes will be terminated. The default is 60
+ in this many minutes are terminated. The default is 60
minutes (1
hour). The maximum value is 28 days (40320 minutes).
</para>
<term><command>notify-rate</command></term>
<listitem>
<para>
- The rate at which NOTIFY requests will be sent
+ This specifies the rate at which NOTIFY requests are sent
during normal zone maintenance operations. (NOTIFY
requests due to initial zone loading are subject
to a separate rate limit; see below.) The default is
20 per second.
The lowest possible rate is one per second; when set
- to zero, it will be silently raised to one.
+ to zero, it is silently raised to one.
</para>
</listitem>
</varlistentry>
<term><command>startup-notify-rate</command></term>
<listitem>
<para>
- The rate at which NOTIFY requests will be sent
+ This is the rate at which NOTIFY requests are sent
when the name server is first starting up, or when
- zones have been newly added to the nameserver.
+ zones have been newly added to the name server.
The default is 20 per second.
The lowest possible rate is one per second; when set
- to zero, it will be silently raised to one.
+ to zero, it is silently raised to one.
</para>
</listitem>
</varlistentry>
<term><command>serial-query-rate</command></term>
<listitem>
<para>
- Slave servers will periodically query master
+ Secondary servers periodically query primary
servers to find out if zone serial numbers have
changed. Each such query uses a minute amount of
- the slave server's network bandwidth. To limit
+ the secondary server's network bandwidth. To limit
the amount of bandwidth used, BIND 9 limits the
rate at which queries are sent. The value of the
<command>serial-query-rate</command> option, an
integer, is the maximum number of queries sent
per second. The default is 20 per second.
The lowest possible rate is one per second; when set
- to zero, it will be silently raised to one.
+ to zero, it is silently raised to one.
</para>
</listitem>
</varlistentry>
<term><command>serial-queries</command></term>
<listitem>
<para>
- In BIND 8, the <command>serial-queries</command>
- option
- set the maximum number of concurrent serial number queries
- allowed to be outstanding at any given time.
BIND 9 does not limit the number of outstanding
serial queries and ignores the <command>serial-queries</command> option.
Instead, it limits the rate at which the queries are sent
<command>one-answer</command> and
<command>many-answers</command>.
The <command>transfer-format</command> option is used
- on the master server to determine which format it sends.
+ on the primary server to determine which format it sends.
<command>one-answer</command> uses one DNS message per
resource record transferred.
<command>many-answers</command> packs as many resource
- records as possible into a message.
- <command>many-answers</command> is more efficient, but is
- only supported by relatively new slave servers,
- such as <acronym>BIND</acronym> 9, <acronym>BIND</acronym>
- 8.x and <acronym>BIND</acronym> 4.9.5 onwards.
+ records as possible into one message.
+ <command>many-answers</command> is more efficient; the default is <command>many-answers</command>.
The <command>many-answers</command> format is also supported by
- recent Microsoft Windows nameservers.
- The default is <command>many-answers</command>.
+ recent Microsoft Windows name servers.
<command>transfer-format</command> may be overridden on a
per-server basis by using the <command>server</command>
statement.
<para>
This is an upper bound on the uncompressed size of DNS
messages used in zone transfers over TCP. If a message
- grows larger than this size, additional messages will be
+ grows larger than this size, additional messages are
used to complete the zone transfer. (Note, however,
that this is a hint, not a hard limit; if a message
contains a single resource record whose RDATA does not
permitted so the record can be transferred.)
</para>
<para>
- Valid values are between 512 and 65535 octets, and any
- values outside that range will be adjusted to the nearest
+ Valid values are between 512 and 65535 octets; any
+ values outside that range are adjusted to the nearest
value within it. The default is <literal>20480</literal>,
- which was selected to improve message compression:
+ which was selected to improve message compression;
most DNS messages of this size will compress to less
than 16536 bytes. Larger messages cannot be compressed
as effectively, because 16536 is the largest permissible
<term><command>transfers-in</command></term>
<listitem>
<para>
- The maximum number of inbound zone transfers
- that can be running concurrently. The default value is <literal>10</literal>.
+ This is the maximum number of inbound zone transfers
+ that can run concurrently. The default value is <literal>10</literal>.
Increasing <command>transfers-in</command> may
speed up the convergence
- of slave zones, but it also may increase the load on the
+ of secondary zones, but it also may increase the load on the
local system.
</para>
</listitem>
<term><command>transfers-out</command></term>
<listitem>
<para>
- The maximum number of outbound zone transfers
- that can be running concurrently. Zone transfer requests in
+ This is the maximum number of outbound zone transfers
+ that can run concurrently. Zone transfer requests in
excess
- of the limit will be refused. The default value is <literal>10</literal>.
+ of the limit are refused. The default value is <literal>10</literal>.
</para>
</listitem>
</varlistentry>
<term><command>transfers-per-ns</command></term>
<listitem>
<para>
- The maximum number of inbound zone transfers
- that can be concurrently transferring from a given remote
+ This is the maximum number of inbound zone transfers
+ that can concurrently transfer from a given remote
name server.
The default value is <literal>2</literal>.
Increasing <command>transfers-per-ns</command>
may
- speed up the convergence of slave zones, but it also may
+ speed up the convergence of secondary zones, but it also may
increase
the load on the remote name server. <command>transfers-per-ns</command> may
be overridden on a per-server basis by using the <command>transfers</command> phrase
<term><command>transfer-source</command></term>
<listitem>
<para><command>transfer-source</command>
- determines which local address will be bound to IPv4
+ determines which local address is bound to IPv4
TCP connections used to fetch zones transferred
inbound by the server. It also determines the
source IPv4 address, and optionally the UDP port,
used for the refresh queries and forwarded dynamic
- updates. If not set, it defaults to a system
- controlled value which will usually be the address
+ updates. If not set, it defaults to a
+ system-controlled value which is usually the address
of the interface "closest to" the remote end. This
address must appear in the remote end's
<command>allow-transfer</command> option for the
<term><command>transfer-source-v6</command></term>
<listitem>
<para>
- The same as <command>transfer-source</command>,
+ This option is the same as <command>transfer-source</command>,
except zone transfers are performed using IPv6.
</para>
</listitem>
<term><command>alt-transfer-source</command></term>
<listitem>
<para>
- An alternate transfer source if the one listed in
+ This indicates an alternate transfer source if the one listed in
<command>transfer-source</command> fails and
<command>use-alt-transfer-source</command> is
set.
</para>
<note><simpara>
- If you do not wish the alternate transfer source
- to be used, you should set
- <command>use-alt-transfer-source</command>
- appropriately and you should not depend upon
+ To avoid using the alternate transfer source,
+ set <command>use-alt-transfer-source</command>
+ appropriately and do not depend upon
getting an answer back to the first refresh
query.
</simpara></note>
<term><command>alt-transfer-source-v6</command></term>
<listitem>
<para>
- An alternate transfer source if the one listed in
+ This indicates an alternate transfer source if the one listed in
<command>transfer-source-v6</command> fails and
<command>use-alt-transfer-source</command> is
set.
<term><command>use-alt-transfer-source</command></term>
<listitem>
<para>
- Use the alternate transfer sources or not. If views are
- specified this defaults to <command>no</command>
- otherwise it defaults to
- <command>yes</command> (for BIND 8
- compatibility).
+ This indicates whether the alternate transfer sources should be used. If views are
+ specified, this defaults to <command>no</command>;
+ otherwise, it defaults to
+ <command>yes</command>.
</para>
</listitem>
</varlistentry>
<listitem>
<para><command>notify-source</command>
determines which local source address, and
- optionally UDP port, will be used to send NOTIFY
- messages. This address must appear in the slave
+ optionally UDP port, is used to send NOTIFY
+ messages. This address must appear in the secondary
server's <command>masters</command> zone clause or
in an <command>allow-notify</command> clause. This
statement sets the <command>notify-source</command>
<term><command>notify-source-v6</command></term>
<listitem>
<para>
- Like <command>notify-source</command>,
+ This option acts like <command>notify-source</command>,
but applies to notify messages sent to IPv6 addresses.
</para>
</listitem>
<command>avoid-v4-udp-ports</command>,
<command>use-v6-udp-ports</command>, and
<command>avoid-v6-udp-ports</command>
- specify a list of IPv4 and IPv6 UDP ports that will be
- used or not used as source ports for UDP messages.
+ specify a list of IPv4 and IPv6 UDP ports that are
+ or are not used as source ports for UDP messages.
See <xref linkend="query_address"/> about how the
available ports are determined.
- For example, with the following configuration
+ For example, with the following configuration:
</para>
<programlisting>
<para>
UDP ports of IPv6 messages sent
- from <command>named</command> will be in one
+ from <command>named</command> are in one
of the following ranges: 32768 to 39999, 40001 to 49999,
and 60001 to 65535.
</para>
<command>avoid-v4-udp-ports</command> and
<command>avoid-v6-udp-ports</command> can be used
to prevent <command>named</command> from choosing as its random source port a
- port that is blocked by your firewall or a port that is
+ port that is blocked by a firewall or a port that is
used by other applications;
if a query went out with a source port blocked by a
firewall, the
- answer would not get by the firewall and the name server would
+ answer would not pass through the firewall and the name server would
have to query again.
Note: the desired range can also be represented only with
<command>use-v4-udp-ports</command> and
<para>
The following options set operating system resource limits for
- the name server process. Some operating systems don't support
+ the name server process. Some operating systems do not support
some or
- any of the limits. On such systems, a warning will be issued if
- the
+ any of the limits; on such systems, a warning is issued if
+ an
unsupported limit is used.
</para>
<term><command>coresize</command></term>
<listitem>
<para>
- The maximum size of a core dump. The default
+ This sets the maximum size of a core dump. The default
is <literal>default</literal>.
</para>
</listitem>
<term><command>datasize</command></term>
<listitem>
<para>
- The maximum amount of data memory the server
+ This sets the maximum amount of data memory the server
may use. The default is <literal>default</literal>.
- This is a hard limit on server memory usage.
- If the server attempts to allocate memory in excess of this
+ This is a hard limit on server memory usage;
+ if the server attempts to allocate memory in excess of this
limit, the allocation will fail, which may in turn leave
the server unable to perform DNS service. Therefore,
- this option is rarely useful as a way of limiting the
+ this option is rarely useful as a way to limit the
amount of memory used by the server, but it can be used
to raise an operating system data size limit that is
- too small by default. If you wish to limit the amount
+ too small by default. To limit the amount
of memory used by the server, use the
<command>max-cache-size</command> and
<command>recursive-clients</command>
<term><command>files</command></term>
<listitem>
<para>
- The maximum number of files the server
+ This sets the maximum number of files the server
may have open concurrently. The default is <literal>unlimited</literal>.
</para>
</listitem>
<term><command>stacksize</command></term>
<listitem>
<para>
- The maximum amount of stack memory the server
+ This sets the maximum amount of stack memory the server
may use. The default is <literal>default</literal>.
</para>
</listitem>
</section>
- <section xml:id="server_resource_limits"><info><title>Server Resource Limits</title></info>
+ <section xml:id="server_resource_limits"><info><title>Server Resource Limits</title></info>
<para>
The following options set limits on the server's
resource consumption that are enforced internally by the
- server rather than the operating system.
+ server rather than by the operating system.
</para>
<variablelist>
<term><command>max-journal-size</command></term>
<listitem>
<para>
- Sets a maximum size for each journal file
+ This sets a maximum size for each journal file
(see <xref linkend="journal"/>). When the journal file
approaches
the specified size, some of the oldest transactions in the
journal
- will be automatically removed. The largest permitted
+ are automatically removed. The largest permitted
value is 2 gigabytes. The default is
<literal>unlimited</literal>, which also
means 2 gigabytes.
- This may also be set on a per-zone basis.
+ This option may also be set on a per-zone basis.
</para>
</listitem>
</varlistentry>
<term><command>max-records</command></term>
<listitem>
<para>
- The maximum number of records permitted in a zone.
- The default is zero which means unlimited.
+ This sets the maximum number of records permitted in a zone.
+ The default is zero, which means the maximum is unlimited.
</para>
</listitem>
</varlistentry>
<term><command>host-statistics-max</command></term>
<listitem>
<para>
- In BIND 8, specifies the maximum number of host statistics
+ In BIND 8, this specified the maximum number of host statistics
entries to be kept.
- Not implemented in BIND 9.
+ It is not implemented in BIND 9.
</para>
</listitem>
</varlistentry>
<term><command>recursive-clients</command></term>
<listitem>
<para>
- The maximum number ("hard quota") of simultaneous
- recursive lookups the server will perform on behalf
+ This sets the maximum number (a "hard quota") of simultaneous
+ recursive lookups the server performs on behalf
of clients. The default is
<literal>1000</literal>. Because each recursing
client uses a fair
</para>
<para>
<option>recursive-clients</option> defines a "hard
- quota" limit for pending recursive clients: when more
+ quota" limit for pending recursive clients; when more
clients than this are pending, new incoming requests
- will not be accepted, and for each incoming request
- a previous pending request will also be dropped.
+ are not accepted, and for each incoming request
+ a previous pending request is dropped.
</para>
<para>
A "soft quota" is also set. When this lower
quota is exceeded, incoming requests are accepted, but
- for each one, a pending request will be dropped.
+ for each one, a pending request is dropped.
If <option>recursive-clients</option> is greater than
1000, the soft quota is set to
<option>recursive-clients</option> minus 100;
<term><command>tcp-clients</command></term>
<listitem>
<para>
- The maximum number of simultaneous client TCP
- connections that the server will accept.
+ This is the maximum number of simultaneous client TCP
+ connections that the server accepts.
The default is <literal>150</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry xml:id="clients-per-query">
- <term xml:id="cpq_term"><command>clients-per-query</command></term>
+ <term xml:id="cpq_term"><command>clients-per-query</command></term>;
<term><command>max-clients-per-query</command></term>
<listitem>
<para>These set the
initial value (minimum) and maximum number of recursive
simultaneous clients for any given query
- (<qname,qtype,qclass>) that the server will accept
- before dropping additional clients. <command>named</command> will attempt to
- self tune this value and changes will be logged. The
+ (<qname,qtype,qclass>) that the server accepts
+ before dropping additional clients. <command>named</command> attempts to
+ self-tune this value and changes are logged. The
default values are 10 and 100.
</para>
<para>
This value should reflect how many queries come in for
a given name in the time it takes to resolve that name.
- If the number of queries exceed this value, <command>named</command> will
- assume that it is dealing with a non-responsive zone
- and will drop additional queries. If it gets a response
- after dropping queries, it will raise the estimate. The
- estimate will then be lowered in 20 minutes if it has
+ If the number of queries exceeds this value, <command>named</command>
+ assumes that it is dealing with a non-responsive zone
+ and drops additional queries. If it gets a response
+ after dropping queries, it raises the estimate. The
+ estimate is then lowered in 20 minutes if it has
remained unchanged.
</para>
<para>
If <command>clients-per-query</command> is set to zero,
- then there is no limit on the number of clients per query
- and no queries will be dropped.
+ there is no limit on the number of clients per query
+ and no queries are dropped.
</para>
<para>
If <command>max-clients-per-query</command> is set to zero,
- then there is no upper bound other than imposed by
+ there is no upper bound other than imposed by
<command>recursive-clients</command>.
</para>
</listitem>
<term><command>fetches-per-zone</command></term>
<listitem>
<para>
- The maximum number of simultaneous iterative
- queries to any one domain that the server will
- permit before blocking new queries for data
+ This sets the maximum number of simultaneous iterative
+ queries to any one domain that the server
+ permits before blocking new queries for data
in or beneath that zone.
This value should reflect how many fetches would
normally be sent to any one zone in the time it
</para>
<para>
When many clients simultaneously query for the
- same name and type, the clients will all be attached
+ same name and type, the clients are all attached
to the same fetch, up to the
<option>max-clients-per-query</option> limit,
- and only one iterative query will be sent.
+ and only one iterative query is sent.
However, when clients are simultaneously
querying for <emphasis>different</emphasis> names
- or types, multiple queries will be sent and
+ or types, multiple queries are sent and
<option>max-clients-per-query</option> is not
effective as a limit.
</para>
Optionally, this value may be followed by the keyword
<literal>drop</literal> or <literal>fail</literal>,
indicating whether queries which exceed the fetch
- quota for a zone will be dropped with no response,
+ quota for a zone are dropped with no response,
or answered with SERVFAIL. The default is
<literal>drop</literal>.
</para>
<para>
If <command>fetches-per-zone</command> is set to zero,
- then there is no limit on the number of fetches per query
- and no queries will be dropped. The default is zero.
+ there is no limit on the number of fetches per query
+ and no queries are dropped. The default is zero.
</para>
<para>
The current list of active fetches can be dumped by
<term><command>fetches-per-server</command></term>
<listitem>
<para>
- The maximum number of simultaneous iterative
- queries that the server will allow to be sent to
+ This sets the maximum number of simultaneous iterative
+ queries that the server allows to be sent to
a single upstream name server before blocking
additional queries.
This value should reflect how many fetches would
<para>
Optionally, this value may be followed by the keyword
<literal>drop</literal> or <literal>fail</literal>,
- indicating whether queries will be dropped with no
- response, or answered with SERVFAIL, when all of the
+ indicating whether queries are dropped with no
+ response or answered with SERVFAIL, when all of the
servers authoritative for a zone are found to have
exceeded the per-server quota. The default is
<literal>fail</literal>.
</para>
<para>
If <command>fetches-per-server</command> is set to zero,
- then there is no limit on the number of fetches per query
- and no queries will be dropped. The default is zero.
+ there is no limit on the number of fetches per query
+ and no queries are dropped. The default is zero.
</para>
<para>
The <command>fetches-per-server</command> quota is
<term><command>fetch-quota-params</command></term>
<listitem>
<para>
- Sets the parameters to use for dynamic resizing of
+ This sets the parameters to use for dynamic resizing of
the <option>fetches-per-server</option> quota in
response to detected congestion.
</para>
The first argument is an integer value indicating
how frequently to recalculate the moving average
of the ratio of timeouts to responses for each
- server. The default is 100, meaning we recalculate
+ server. The default is 100, meaning that BIND recalculates
the average ratio after every 100 queries have either
been answered or timed out.
</para>
events to weigh more heavily, smoothing out
short-term blips in the timeout ratio.
These arguments are all fixed-point numbers with
- precision of 1/100: at most two places after
+ precision of 1/100; at most two places after
the decimal point are significant.
</para>
</listitem>
<term><command>reserved-sockets</command></term>
<listitem>
<para>
- The number of file descriptors reserved for TCP, stdio,
+ This sets the number of file descriptors reserved for TCP, stdio,
etc. This needs to be big enough to cover the number of
interfaces <command>named</command> listens on plus
<command>tcp-clients</command>, as well as
to provide room for outgoing TCP queries and incoming zone
transfers. The default is <literal>512</literal>.
The minimum value is <literal>128</literal> and the
- maximum value is <literal>128</literal> less than
+ maximum value is <literal>128</literal> fewer than
maxsockets (-S). This option may be removed in the future.
</para>
<para>
<term><command>max-cache-size</command></term>
<listitem>
<para>
- The maximum amount of memory to use for the
- server's cache, in bytes or % of total physical memory.
+ This sets the maximum amount of memory to use for the
+ server's cache, in bytes or percentage of total physical memory.
When the amount of data in the cache
- reaches this limit, the server will cause records to
- expire prematurely based on an LRU based strategy so
+ reaches this limit, the server causes records to
+ expire prematurely, following an LRU-based strategy, so
that the limit is not exceeded.
The keyword <userinput>unlimited</userinput>,
- or the value 0, will place no limit on cache size;
- records will be purged from the cache only when their
+ or the value 0, places no limit on the cache size;
+ records are purged from the cache only when their
TTLs expire.
- Any positive values less than 2MB will be ignored
+ Any positive values less than 2MB are ignored
and reset to 2MB.
In a server with multiple views, the limit applies
separately to the cache of each view.
The default is <userinput>90%</userinput>.
- On systems where detection of amount of physical
- memory is not supported values represented as %
+ On systems where detection of the amount of physical
+ memory is not supported, values represented as a percentage
fall back to unlimited.
Note that the detection of physical memory is done only
- once at startup, so <command>named</command> will not
+ once at startup, so <command>named</command> does not
adjust the cache size if the amount of physical memory
is changed during runtime.
</para>
<term><command>tcp-listen-queue</command></term>
<listitem>
<para>
- The listen queue depth. The default and minimum is 10.
- If the kernel supports the accept filter "dataready" this
+ This sets the listen-queue depth. The default and minimum is 10.
+ If the kernel supports the accept filter "dataready", this
also controls how
- many TCP connections that will be queued in kernel space
+ many TCP connections are queued in kernel space
waiting for
- some data before being passed to accept. Nonzero values
- less than 10 will be silently raised. A value of 0 may also
- be used; on most platforms this sets the listen queue
+ some data before being passed to accept. Non-zero values
+ less than 10 are silently raised. A value of 0 may also
+ be used; on most platforms this sets the listen-queue
length to a system-defined default value.
</para>
</listitem>
<listitem>
<para>
This interval is effectively obsolete. Previously,
- the server would remove expired resource records
+ the server removed expired resource records
from the cache every <command>cleaning-interval</command> minutes.
<acronym>BIND</acronym> 9 now manages cache
memory in a more sophisticated manner and does not
- rely on the periodic cleaning any more.
+ rely on periodic cleaning anymore.
Specifying this option therefore has no effect on
the server's behavior.
</para>
<term><command>heartbeat-interval</command></term>
<listitem>
<para>
- The server will perform zone maintenance tasks
+ The server performs zone maintenance tasks
for all zones marked as <command>dialup</command> whenever this
interval expires. The default is 60 minutes. Reasonable
values are up
to 1 day (1440 minutes). The maximum value is 28 days
(40320 minutes).
- If set to 0, no zone maintenance for these zones will occur.
+ If set to 0, no zone maintenance for these zones occurs.
</para>
</listitem>
</varlistentry>
<term><command>interface-interval</command></term>
<listitem>
<para>
- The server will scan the network interface list
+ The server scans the network interface list
every <command>interface-interval</command>
minutes. The default
- is 60 minutes. The maximum value is 28 days (40320 minutes).
- If set to 0, interface scanning will only occur when
+ is 60 minutes; the maximum value is 28 days (40320 minutes).
+ If set to 0, interface scanning only occurs when
the configuration file is loaded, or when
<command>automatic-interface-scan</command> is enabled
and supported by the operating system. After the scan, the
- server will begin listening for queries on any newly
+ server begins listening for queries on any newly
discovered interfaces (provided they are allowed by the
<command>listen-on</command> configuration), and
- will
- stop listening on interfaces that have gone away.
+ stops listening on interfaces that have gone away.
</para>
</listitem>
</varlistentry>
<term><command>statistics-interval</command></term>
<listitem>
<para>
- Name server statistics will be logged
+ Name server statistics are logged
every <command>statistics-interval</command>
minutes. The default is
- 60. The maximum value is 28 days (40320 minutes).
- If set to 0, no statistics will be logged.
+ 60, and the maximum value is 28 days (40320 minutes).
+ If set to 0, no statistics are logged.
</para><note>
<simpara>
- Not yet implemented in
+ This option is not implemented in
<acronym>BIND</acronym> 9.
</simpara>
</note>
<para>
In BIND 8, this option indicated network topology
so that preferential treatment could be given to
- the topologicaly closest name servers when sending
+ the topologically closest name servers when sending
queries. It is not implemented in BIND 9.
</para>
</listitem>
<para>
The response to a DNS query may consist of multiple resource
records (RRs) forming a resource record set (RRset). The name
- server will normally return the RRs within the RRset in an
+ server normally returns the RRs within the RRset in an
indeterminate order (but see the <command>rrset-order</command>
statement in <xref linkend="rrset_ordering"/>). The client
- resolver code should rearrange the RRs as appropriate, that is,
+ resolver code should rearrange the RRs as appropriate: that is,
using any addresses on the local net in preference to other
addresses. However, not all resolvers can do this or are
correctly configured. When a client is using a local server,
<para>
The <command>sortlist</command> statement (see below) takes an
<command>address_match_list</command> and interprets it in a
- special way. Each top level statement in the
+ special way. Each top-level statement in the
<command>sortlist</command> must itself be an explicit
<command>address_match_list</command> with one or two elements.
The first element (which may be an IP address, an IP prefix, an
- ACL name or a nested <command>address_match_list</command>) of
- each top level list is checked against the source address of
+ ACL name, or a nested <command>address_match_list</command>) of
+ each top-level list is checked against the source address of
the query until a match is found. When the addresses in the
- first element overlap, the first rule to match gets selected.
+ first element overlap, the first rule to match is selected.
</para>
<para>
Once the source address of the query has been matched, if the
- top level statement contains only one element, the actual
+ top-level statement contains only one element, the actual
primitive element that matched the source address is used to
select the address in the response to move to the beginning of
the response. If the statement is a list of two elements, then
the second element is interpreted as a topology preference
- list. Each top level element is assigned a distance and the
+ list. Each top-level element is assigned a distance, and the
address in the response with the minimum distance is moved to
the beginning of the response.
</para>
<para>
In the following example, any queries received from any of the
- addresses of the host itself will get responses preferring
+ addresses of the host itself get responses preferring
addresses on any of the locally connected networks. Next most
preferred are addresses on the 192.168.1/24 network, and after
- that either the 192.168.2/24 or 192.168.3/24 network with no
+ that either the 192.168.2/24 or 192.168.3/24 network, with no
preference shown between these two networks. Queries received
- from a host on the 192.168.1/24 network will prefer other
+ from a host on the 192.168.1/24 network prefer other
addresses on that network to the 192.168.2/24 and 192.168.3/24
networks. Queries received from a host on the 192.168.4/24 or
- the 192.168.5/24 network will only prefer other addresses on
+ the 192.168.5/24 network only prefer other addresses on
their directly connected networks.
</para>
};</programlisting>
<para>
- The following example will give reasonable behavior for the
- local host and hosts on directly connected networks. It is
- similar to the behavior of the address sort in
- <acronym>BIND</acronym> 4.9.x. Responses sent to queries from
- the local host will favor any of the directly connected
+ The following example illustrates reasonable behavior for the
+ local host and hosts on directly connected networks. Responses sent to queries from
+ the local host favor any of the directly connected
networks. Responses sent to queries from any other hosts on a
- directly connected network will prefer addresses on that same
- network. Responses to other queries will not be sorted.
+ directly connected network prefer addresses on that same
+ network. Responses to other queries are not sorted.
</para>
<programlisting>sortlist {
<section xml:id="rrset_ordering"><info><title xml:id="rrset_ordering_title">RRset Ordering</title></info>
<para>
- When multiple records are returned in an answer it may be
+ When multiple records are returned in an answer, it may be
useful to configure the order of the records placed into the
response.
The <command>rrset-order</command> statement permits
configuration
- of the ordering of the records in a multiple record response.
+ of the ordering of the records in a multiple-record response.
See also the <command>sortlist</command> statement,
<xref linkend="the_sortlist_statement"/>.
</para>
</entry>
<entry colname="2">
<para>
- Records are returned in some random order.
+ Records are returned in a random order.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Records are returned in a cyclic round-robin order.
+ Records are returned in a cyclic round-robin order, rotating by one record per query.
</para>
<para>
If <acronym>BIND</acronym> is configured with the
- "--enable-fixed-rrset" option at compile time, then
- the initial ordering of the RRset will match the
+ "--enable-fixed-rrset" option at compile time,
+ the initial ordering of the RRset matches the
one specified in the zone file.
</para>
</entry>
</programlisting>
<para>
- will cause any responses for type A records in class IN that
+ causes any responses for type A records in class IN, that
have "<literal>host.example.com</literal>" as a
suffix, to always be returned
in random order. All other records are returned in cyclic order.
</para>
<para>
If multiple <command>rrset-order</command> statements
- appear, they are not combined — the last one applies.
+ appear, they are not combined; the last one applies.
</para>
<para>
- By default, all records are returned in random order.
+ By default, records are returned in random order.
</para>
<note>
<term><command>lame-ttl</command></term>
<listitem>
<para>
- Sets the number of seconds to cache a
+ This sets the number of seconds to cache a
lame server indication. 0 disables caching. (This is
<emphasis role="bold">NOT</emphasis> recommended.)
The default is <literal>600</literal> (10 minutes) and the
<term><command>servfail-ttl</command></term>
<listitem>
<para>
- Sets the number of seconds to cache a
+ This sets the number of seconds to cache a
SERVFAIL response due to DNSSEC validation failure or
other general server failure. If set to
<literal>0</literal>, SERVFAIL caching is disabled.
</para>
<para>
The maximum value is <literal>30</literal>
- seconds; any higher value will be silently
+ seconds; any higher value is silently
reduced. The default is <literal>1</literal>
second.
</para>
To reduce network traffic and increase performance,
the server stores negative answers. <command>max-ncache-ttl</command> is
used to set a maximum retention time for these answers in
- the server
+ the server,
in seconds. The default
<command>max-ncache-ttl</command> is <literal>10800</literal> seconds (3 hours).
<command>max-ncache-ttl</command> cannot exceed
- 7 days and will
- be silently truncated to 7 days if set to a greater value.
+ 7 days and is
+ silently truncated to 7 days if set to a greater value.
</para>
</listitem>
</varlistentry>
<term><command>max-cache-ttl</command></term>
<listitem>
<para>
- Sets the maximum time for which the server will
- cache ordinary (positive) answers in seconds.
+ This sets the maximum time for which the server
+ caches ordinary (positive) answers, in seconds.
The default is 604800 (one week).
A value of zero may cause all queries to return
SERVFAIL, because of lost caches of intermediate
<term><command>min-roots</command></term>
<listitem>
<para>
- The minimum number of root servers that
+ This sets the minimum number of root servers that
is required for a request for the root servers to be
accepted. The default
is <userinput>2</userinput>.
</para>
<note>
<simpara>
-
Not implemented in <acronym>BIND</acronym> 9.
+
This is not implemented in <acronym>BIND</acronym> 9.
</simpara>
</note>
</listitem>
<term><command>sig-validity-interval</command></term>
<listitem>
<para>
- Specifies the number of days into the future when
- DNSSEC signatures automatically generated as a
+ This specifies the number of days into the future that
+ DNSSEC signatures that are automatically generated as a
result of dynamic updates (<xref linkend="dynamic_update"/>) will expire. There
is an optional second field which specifies how
- long before expiry that the signatures will be
- regenerated. If not specified, the signatures will
- be regenerated at 1/4 of base interval. The second
+ long before expiry that the signatures are
+ regenerated. If not specified, the signatures are
+ regenerated at 1/4 of base interval. The second
field is specified in days if the base interval is
- greater than 7 days otherwise it is specified in hours.
- The default base interval is <literal>30</literal> days
+ greater than 7 days; otherwise it is specified in hours.
+ The default base interval is <literal>30</literal> days,
giving a re-signing interval of 7 1/2 days. The maximum
- values are 10 years (3660 days).
+ value is 10 years (3660 days).
</para>
<para>
The signature inception time is unconditionally
- set to one hour before the current time to allow
+ set to one hour before the current time, to allow
for a limited amount of clock skew.
</para>
<para>
The <command>sig-validity-interval</command>
- should be, at least, several multiples of the SOA
- expire interval to allow for reasonable interaction
+ should be at least several multiples of the SOA
+ expire interval, to allow for reasonable interaction
between the various timer and expiry dates.
</para>
</listitem>
<term><command>sig-signing-nodes</command></term>
<listitem>
<para>
- Specify the maximum number of nodes to be
- examined in each quantum when signing a zone with
+ This specifies the maximum number of nodes to be
+ examined in each quantum, when signing a zone with
a new DNSKEY. The default is
<literal>100</literal>.
</para>
<term><command>sig-signing-signatures</command></term>
<listitem>
<para>
- Specify a threshold number of signatures that
- will terminate processing a quantum when signing
+ This specifies a threshold number of signatures that
+ terminates processing a quantum, when signing
a zone with a new DNSKEY. The default is
<literal>10</literal>.
</para>
<term><command>sig-signing-type</command></term>
<listitem>
<para>
- Specify a private RDATA type to be used when generating
- signing state records. The default is
+ This specifies a private RDATA type to be used when generating
+ signing-state records. The default is
<literal>65534</literal>.
</para>
<para>
- It is expected that this parameter may be removed
- in a future version once there is a standard type.
+ This parameter may be removed
+ in a future version, once there is a standard type.
</para>
<para>
- Signing state records are used to internally by
+ Signing-state records are used internally by
<command>named</command> to track the current state of
a zone-signing process, i.e., whether it is still active
or has been completed. The records can be inspected
using the command
<command>rndc signing -list <replaceable>zone</replaceable></command>.
Once <command>named</command> has finished signing
- a zone with a particular key, the signing state
+ a zone with a particular key, the signing-state
record associated with that key can be removed from
the zone by running
<command>rndc signing -clear <replaceable>keyid/algorithm</replaceable> <replaceable>zone</replaceable></command>.
- To clear all of the completed signing state
+ To clear all of the completed signing-state
records for a zone, use
<command>rndc signing -clear all <replaceable>zone</replaceable></command>.
</para>
zone (querying for SOA changes) or retrying failed
transfers. Usually the SOA values for the zone are used,
up to a hard-coded maximum expiry of 24 weeks. However,
- these values are set by the master, giving slave server
+ these values are set by the primary, giving secondary server
administrators little control over their contents.
</para>
<para>
These options allow the administrator to set a minimum and
maximum refresh and retry time in seconds per-zone,
per-view, or globally. These options are valid for
- slave and stub zones, and clamp the SOA refresh and
+ secondary and stub zones, and clamp the SOA refresh and
retry times to the specified values.
</para>
<para>
- The following defaults apply.
+ The following defaults apply:
<command>min-refresh-time</command> 300 seconds,
<command>max-refresh-time</command> 2419200 seconds
(4 weeks), <command>min-retry-time</command> 500 seconds,
<term><command>edns-udp-size</command></term>
<listitem>
<para>
- Sets the maximum advertised EDNS UDP buffer size in
+ This sets the maximum advertised EDNS UDP buffer size, in
bytes, to control the size of packets received from
authoritative servers in response to recursive queries.
- Valid values are 512 to 4096 (values outside this range
- will be silently adjusted to the nearest value within
- it). The default value is 4096.
+ Valid values are 512 to 4096; values outside this range
+ are silently adjusted to the nearest value within
+ it. The default value is 4096.
</para>
<para>
The usual reason for setting
</para>
<para>
When <command>named</command> first queries a remote
- server, it will advertise a UDP buffer size of 512, as
+ server, it advertises a UDP buffer size of 512, as
this has the greatest chance of success on the first try.
</para>
<para>
If the initial response times out, <command>named</command>
- will try again with plain DNS, and if that is successful,
- it will be taken as evidence that the server does not
+ tries again with plain DNS; if that is successful,
+ it is taken as evidence that the server does not
support EDNS. After enough failures using EDNS and
successes using plain DNS, <command>named</command>
- will default to plain DNS for future communications
- with that server. (Periodically, <command>named</command>
- will send an EDNS query to see if the situation has
- improved.)
+ defaults to plain DNS for future communications
+ with that server. If that happens, <command>named</command>
+ periodically sends an EDNS query to see if the situation has
+ improved.
</para>
<para>
However, if the initial query is successful with
EDNS advertising a buffer size of 512, then
- <command>named</command> will advertise progressively
+ <command>named</command> advertises progressively
larger buffer sizes on successive queries, until
responses begin timing out or
<command>edns-udp-size</command> is reached.
</para>
<para>
The default buffer sizes used by <command>named</command>
- are 512, 1232, 1432, and 4096, but never exceeding
+ are 512, 1232, 1432, and 4096, but never exceed
<command>edns-udp-size</command>. (The values 1232 and
- 1432 are chosen to allow for an IPv4/IPv6 encapsulated
+ 1432 are chosen to allow for an IPv4-/IPv6-encapsulated
UDP message to be sent without fragmentation at the
minimum MTU sizes for Ethernet and IPv6 networks.)
</para>
<term><command>max-udp-size</command></term>
<listitem>
<para>
- Sets the maximum EDNS UDP message size
- <command>named</command> will send in bytes.
- Valid values are 512 to 4096 (values outside this
- range will be silently adjusted to the nearest
- value within it). The default value is 4096.
+ This sets the maximum EDNS UDP message size that
+ <command>named</command> sends, in bytes.
+ Valid values are 512 to 4096; values outside this
+ range are silently adjusted to the nearest
+ value within it. The default value is 4096.
</para>
<para>
This value applies to responses sent by a server; to
<para>
The usual reason for setting
<command>max-udp-size</command> to a non-default
- value is to get UDP answers to pass through broken
+ value is to allow UDP answers to pass through broken
firewalls that block fragmented packets and/or
block UDP packets that are greater than 512 bytes.
This is independent of the advertised receive
buffer (<command>edns-udp-size</command>).
</para>
<para>
- Setting this to a low value will encourage additional
- TCP traffic to the nameserver.
+ Setting this to a low value encourages additional
+ TCP traffic to the name server.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>masterfile-format</command></term>
<listitem>
- <para>Specifies
+ <para>This specifies
the file format of zone files (see
<xref linkend="zonefile_format"/>).
The default value is <constant>text</constant>, which is the
- standard textual representation, except for slave zones,
+ standard textual representation, except for secondary zones,
in which the default value is <constant>raw</constant>.
- Files in other formats than <constant>text</constant> are
+ Files in formats other than <constant>text</constant> are
typically expected to be generated by the
<command>named-compilezone</command> tool, or dumped by
<command>named</command>.
</para>
<para>
- Note that when a zone file in a different format than
+ Note that when a zone file in a format other than
<constant>text</constant> is loaded, <command>named</command>
may omit some of the checks which would be performed for a
- file in the <constant>text</constant> format. In particular,
+ file in <constant>text</constant> format. In particular,
<command>check-names</command> checks do not apply
for the <constant>raw</constant> format. This means
a zone file in the <constant>raw</constant> format
<term><command>masterfile-style</command></term>
<listitem>
<para>
- Specifies the formatting of zone files during dump
+ This specifies the formatting of zone files during dump,
when the <option>masterfile-format</option> is
- <constant>text</constant>. (This option is ignored
- with any other <option>masterfile-format</option>.)
+ <constant>text</constant>. This option is ignored
+ with any other <option>masterfile-format</option>.
</para>
<para>
When set to <constant>relative</constant>,
- records are printed in a multi-line format with owner
+ records are printed in a multi-line format, with owner
names expressed relative to a shared origin. When set
to <constant>full</constant>, records are printed in
a single-line format with absolute owner names.
<term><command>max-recursion-depth</command></term>
<listitem>
<para>
- Sets the maximum number of levels of recursion
+ This sets the maximum number of levels of recursion
that are permitted at any one time while servicing
a recursive query. Resolving a name may require
looking up a name server address, which in turn
- requires resolving another name, etc; if the number
- of indirections exceeds this value, the recursive
+ requires resolving another name, etc.; if the number
+ of recursions exceeds this value, the recursive
query is terminated and returns SERVFAIL. The
default is 7.
</para>
<term><command>max-recursion-queries</command></term>
<listitem>
<para>
- Sets the maximum number of iterative queries that
+ This sets the maximum number of iterative queries that
may be sent while servicing a recursive query.
If more queries are sent, the recursive query
is terminated and returns SERVFAIL. The default is 75.
<term><command>notify-delay</command></term>
<listitem>
<para>
- The delay, in seconds, between sending sets of notify
- messages for a zone. The default is five (5) seconds.
+ This sets the delay, in seconds, between sending sets of NOTIFY
+ messages for a zone. The default is 5 seconds.
</para>
<para>
- The overall rate that NOTIFY messages are sent for all
+ The overall rate at which NOTIFY messages are sent for all
zones is controlled by <command>serial-query-rate</command>.
</para>
</listitem>
<term><command>max-rsa-exponent-size</command></term>
<listitem>
<para>
- The maximum RSA exponent size, in bits, that will
- be accepted when validating. Valid values are 35
- to 4096 bits. The default zero (0) is also accepted
+ This sets the maximum RSA exponent size, in bits, that is
+ accepted when validating. Valid values are 35
+ to 4096 bits. The default, zero, is also accepted
and is equivalent to 4096.
</para>
</listitem>
answer available.
</para>
<para>
- The <option>prefetch</option> specifies the
+ <option>prefetch</option> specifies the
"trigger" TTL value at which prefetch of the current
- query will take place: when a cache record with a
+ query takes place; when a cache record with a
lower TTL value is encountered during query processing,
- it will be refreshed. Valid trigger TTL values are 1 to
- 10 seconds. Values larger than 10 seconds will be silently
+ it is refreshed. Valid trigger TTL values are 1 to
+ 10 seconds. Values larger than 10 seconds are silently
reduced to 10.
- Setting a trigger TTL to zero (0) causes
+ Setting a trigger TTL to zero causes
prefetch to be disabled.
The default trigger TTL is <literal>2</literal>.
</para>
<para>
An optional second argument specifies the "eligibility"
TTL: the smallest <emphasis>original</emphasis>
- TTL value that will be accepted for a record to be
+ TTL value that is accepted for a record to be
eligible for prefetching. The eligibility TTL must
be at least six seconds longer than the trigger TTL;
- if it isn't, <command>named</command> will silently
- adjust it upward.
+ if not, <command>named</command> silently
+ adjusts it upward.
The default eligibility TTL is <literal>9</literal>.
</para>
</listitem>
<term><command>v6-bias</command></term>
<listitem>
<para>
- When determining the next nameserver to try
- preference IPv6 nameservers by this many milliseconds.
+ When determining the next name server to try,
+ this indicates by how many milliseconds to prefer IPv6 name servers.
The default is <literal>50</literal> milliseconds.
</para>
</listitem>
</section>
- <section xml:id="builtin"><info><title>Built-in server information zones</title></info>
+ <section xml:id="builtin"><info><title>Built-in Server Information Zones</title></info>
<para>
The server provides some helpful diagnostic information
of a
built-in view (see <xref linkend="view_statement_grammar"/>) of
class
- <command>CHAOS</command> which is separate from the
+ <command>CHAOS</command>, which is separate from the
default view of class <command>IN</command>. Most global
configuration options (<command>allow-query</command>,
- etc) will apply to this view, but some are locally
+ etc.) apply to this view, but some are locally
overridden: <command>notify</command>,
- <command>recursion</command> and
+ <command>recursion</command>, and
<command>allow-new-zones</command> are
always set to <userinput>no</userinput>, and
<command>rate-limit</command> is set to allow
three responses per second.
</para>
<para>
- If you need to disable these zones, use the options
- below, or hide the built-in <command>CHAOS</command>
+ To disable these zones, use the options
+ below or hide the built-in <command>CHAOS</command>
view by
defining an explicit view of class <command>CHAOS</command>
that matches all clients.
<term><command>version</command></term>
<listitem>
<para>
- The version the server should report
+ This is the version the server should report
via a query of the name <literal>version.bind</literal>
- with type <command>TXT</command>, class <command>CHAOS</command>.
+ with type <command>TXT</command> and class <command>CHAOS</command>.
The default is the real version number of this server.
Specifying <command>version none</command>
disables processing of the queries.
</para>
<para>
Setting <command>version</command> to any value
- (including <literal>none</literal>) will also
- disable queries for <literal>authors.bind TXT CH</literal>.
+ (including <literal>none</literal>) also
+ disables queries for <literal>authors.bind TXT CH</literal>.
</para>
</listitem>
</varlistentry>
<term><command>hostname</command></term>
<listitem>
<para>
- The hostname the server should report via a query of
+ This is the hostname the server should report via a query of
the name <filename>hostname.bind</filename>
- with type <command>TXT</command>, class <command>CHAOS</command>.
+ with type <command>TXT</command> and class <command>CHAOS</command>.
This defaults to the hostname of the machine hosting the
- name server as
- found by the gethostname() function. The primary purpose of such queries
+ name server, as
+ found by the <command>gethostname()</command> function. The primary purpose of such queries
is to
identify which of a group of anycast servers is actually
- answering your queries. Specifying <command>hostname none;</command>
+ answering the queries. Specifying <command>hostname none;</command>
disables processing of the queries.
</para>
</listitem>
<term><command>server-id</command></term>
<listitem>
<para>
- The ID the server should report when receiving a Name
+ This is the ID the server should report when receiving a Name
Server Identifier (NSID) query, or a query of the name
<filename>ID.SERVER</filename> with type
- <command>TXT</command>, class <command>CHAOS</command>.
+ <command>TXT</command> and class <command>CHAOS</command>.
The primary purpose of such queries is to
identify which of a group of anycast servers is actually
- answering your queries. Specifying <command>server-id none;</command>
+ answering the queries. Specifying <command>server-id none;</command>
disables processing of the queries.
- Specifying <command>server-id hostname;</command> will cause <command>named</command> to
- use the hostname as found by the gethostname() function.
+ Specifying <command>server-id hostname;</command> causes <command>named</command> to
+ use the hostname as found by the <command>gethostname()</command> function.
The default <command>server-id</command> is <command>none</command>.
</para>
</listitem>
<para>
The <command>named</command> server has some built-in
- empty zones (SOA and NS records only).
+ empty zones, for SOA and NS records only.
These are for zones that should normally be answered locally
and which queries should not be sent to the Internet's root
servers. The official servers which cover these namespaces
return NXDOMAIN responses to these queries. In particular,
these cover the reverse namespaces for addresses from
- RFC 1918, RFC 4193, RFC 5737 and RFC 6598. They also include the
- reverse namespace for IPv6 local address (locally assigned),
- IPv6 link local addresses, the IPv6 loopback address and the
+ RFC 1918, RFC 4193, RFC 5737, and RFC 6598. They also include the
+ reverse namespace for the IPv6 local address (locally assigned),
+ IPv6 link local addresses, the IPv6 loopback address, and the
IPv6 unknown address.
</para>
<para>
- The server will attempt to determine if a built-in zone
+ The server attempts to determine if a built-in zone
already exists or is active (covered by a forward-only
- forwarding declaration) and will not create an empty
- zone in that case.
+ forwarding declaration) and does not create an empty
+ zone if either is true.
</para>
<para>
The current list of empty zones is:
</itemizedlist>
</para>
<para>
- Empty zones are settable at the view level and only apply to
+ Empty zones can be set at the view level and only apply to
views of class IN. Disabled empty zones are only inherited
from options if there are no disabled empty zones specified
at the view level. To override the options list of disabled
- zones, you can disable the root zone at the view level, for example:
+ zones, disable the root zone at the view level. For example:
<programlisting>
disable-empty-zone ".";
</programlisting>
</para>
<para>
- If you are using the address ranges covered here, you should
- already have reverse zones covering the addresses you use.
- In practice this appears to not be the case with many queries
+ If using the address ranges covered here,
+ reverse zones covering the addresses should already be in place.
+ In practice this appears to not be the case, with many queries
being made to the infrastructure servers for names in these
- spaces. So many in fact that sacrificial servers were needed
+ spaces. So many, in fact, that sacrificial servers had
to be deployed to channel the query load away from the
infrastructure servers.
</para>
<note><simpara>
The real parent servers for these zones should disable all
- empty zone under the parent zone they serve. For the real
- root servers, this is all built-in empty zones. This will
- enable them to return referrals to deeper in the tree.
+ empty zones under the parent zone they serve. For the real
+ root servers, this is all built-in empty zones. This
+ enables them to return referrals to deeper in the tree.
</simpara></note>
<variablelist>
<varlistentry>
<term><command>empty-server</command></term>
<listitem>
<para>
- Specify what server name will appear in the returned
- SOA record for empty zones. If none is specified, then
- the zone's name will be used.
+ This specifies the server name that appears in the returned
+ SOA record for empty zones. If none is specified,
+ the zone's name is used.
</para>
</listitem>
</varlistentry>
<term><command>empty-contact</command></term>
<listitem>
<para>
- Specify what contact name will appear in the returned
- SOA record for empty zones. If none is specified, then
- "." will be used.
+ This specifies the contact name that appears in the returned
+ SOA record for empty zones. If none is specified,
+ "." is used.
</para>
</listitem>
</varlistentry>
<term><command>empty-zones-enable</command></term>
<listitem>
<para>
- Enable or disable all empty zones. By default, they
+ This enables or disables all empty zones. By default, they
are enabled.
</para>
</listitem>
<term><command>disable-empty-zone</command></term>
<listitem>
<para>
- Disable individual empty zones. By default, none are
+ This disables individual empty zones. By default, none are
disabled. This option can be specified multiple times.
</para>
</listitem>
<para>
The additional section cache, also called <command>acache</command>,
is an internal cache to improve the response performance of BIND 9.
- When additional section caching is enabled, BIND 9 will
- cache an internal short-cut to the additional section content for
+ When additional section caching is enabled, BIND 9
+ caches an internal shortcut to the additional section content for
each answer RR.
Note that <command>acache</command> is an internal caching
mechanism of BIND 9, and is not related to the DNS caching
<para>
Additional section caching does not change the
response content (except the RRsets ordering of the additional
- section, see below), but can improve the response performance
+ section; see below), but can improve the response performance
significantly.
It is particularly effective when BIND 9 acts as an authoritative
server for a zone that has many delegations with many glue RRs.
</para>
<para>
- In order to obtain the maximum performance improvement
+ To obtain the maximum performance improvement
from additional section caching, setting
<command>additional-from-cache</command>
to <command>no</command> is recommended, since the current
implementation of <command>acache</command>
- does not short-cut of additional section information from the
+ does not shortcut additional section information from the
DNS cache data.
</para>
that it requires much more
memory for the internal cached data.
Thus, if the response performance does not matter and memory
- consumption is much more critical, the
+ consumption is more critical, the
<command>acache</command> mechanism can be
disabled by setting <command>acache-enable</command> to
<command>no</command>.
It is also possible to specify the upper limit of memory
consumption
- for acache by using <command>max-acache-size</command>.
+ for <command>acache</command> by using <command>max-acache-size</command>.
</para>
<para>
RRset ordering in the additional section.
Without <command>acache</command>,
<command>cyclic</command> order is effective for the additional
- section as well as the answer and authority sections.
+ section as well as for the answer and authority sections.
However, additional section caching fixes the ordering when it
first caches an RRset for the additional section, and the same
- ordering will be kept in succeeding responses, regardless of the
+ ordering is kept in succeeding responses, regardless of the
setting of <command>rrset-order</command>.
The effect of this should be minor, however, since an
RRset in the additional section
typically only contains a small number of RRs (and in many cases
- it only contains a single RR), in which case the
- ordering does not matter much.
+ only a single RR), so the
+ ordering is not significant.
</para>
<para>
<term><command>acache-cleaning-interval</command></term>
<listitem>
<para>
- The server will remove stale cache entries, based on an LRU
- based
+ The server removes stale cache entries, based on an LRU-based
algorithm, every <command>acache-cleaning-interval</command> minutes.
The default is 60 minutes.
- If set to 0, no periodic cleaning will occur.
+ If set to 0, no periodic cleaning occurs.
</para>
</listitem>
</varlistentry>
<term><command>max-acache-size</command></term>
<listitem>
<para>
- The maximum amount of memory in bytes to use for the server's acache.
+ This is the maximum amount of memory, in bytes, to use for the server's acache.
When the amount of data in the acache reaches this limit,
the server
- will clean more aggressively so that the limit is not
+ cleans more aggressively so that the limit is not
exceeded.
In a server with multiple views, the limit applies
separately to the
- acache of each view.
+ <command>acache</command> of each view.
The default is <literal>16M</literal>.
</para>
</listitem>
<para>
<acronym>BIND</acronym> 9 provides the ability to filter
- out DNS responses from external DNS servers containing
+ out responses from external DNS servers containing
certain types of data in the answer section.
Specifically, it can reject address (A or AAAA) records if
the corresponding IPv4 or IPv6 addresses match the given
the <varname>name_list</varname> elements.
If the optional <varname>namelist</varname> is specified
with <command>except-from</command>, records whose query name
- matches the list will be accepted regardless of the filter
+ matches the list are accepted regardless of the filter
setting.
Likewise, if the alias name is a subdomain of the
corresponding zone, the <command>deny-answer-aliases</command>
- filter will not apply;
+ filter does not apply;
for example, even if "example.com" is specified for
<command>deny-answer-aliases</command>,
</para>
<programlisting>www.example.com. CNAME xxx.example.com.</programlisting>
<para>
- returned by an "example.com" server will be accepted.
+ returned by an "example.com" server is accepted.
</para>
<para>
<varname>ip_addr</varname>
and <varname>ip_prefix</varname>
are meaningful;
- any <varname>key_id</varname> will be silently ignored.
+ any <varname>key_id</varname> is silently ignored.
</para>
<para>
If a response message is rejected due to the filtering,
the entire message is discarded without being cached, and
- a SERVFAIL error will be returned to the client.
+ a SERVFAIL error is returned to the client.
</para>
<para>
This filtering is intended to prevent "DNS rebinding attacks," in
which an attacker, in response to a query for a domain name the
- attacker controls, returns an IP address within your own network or
- an alias name within your own domain.
+ attacker controls, returns an IP address within the user's own network or
+ an alias name within the user's own domain.
A naive web browser or script could then serve as an
unintended proxy, allowing the attacker
- to get access to an internal node of your local network
- that couldn't be externally accessed otherwise.
+ to get access to an internal node of the local network
+ that could not be externally accessed otherwise.
See the paper available at
- <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://portal.acm.org/citation.cfm?id=1315245.1315298">
- http://portal.acm.org/citation.cfm?id=1315245.1315298
+ <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://dl.acm.org/doi/10.1145/1315245.1315298">
+ https://dl.acm.org/doi/10.1145/1315245.1315298
</link>
- for more details about the attacks.
+ for more details about these attacks.
</para>
<para>
- For example, if you own a domain named "example.net" and
- your internal network uses an IPv4 prefix 192.0.2.0/24,
- you might specify the following rules:
+ For example, with a domain named "example.net" and
+ an internal network using an IPv4 prefix 192.0.2.0/24,
+ an administrator might specify the following rules:
</para>
<programlisting>deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
</programlisting>
<para>
- If an external attacker lets a web browser in your local
+ If an external attacker let a web browser in the local
network look up an IPv4 address of "attacker.example.com",
the attacker's DNS server would return a response like this:
</para>
<para>
in the answer section.
Since the rdata of this record (the IPv4 address) matches
- the specified prefix 192.0.2.0/24, this response will be
+ the specified prefix 192.0.2.0/24, this response would be
ignored.
</para>
<para>
- On the other hand, if the browser looks up a legitimate
+ On the other hand, if the browser looked up a legitimate
internal web server "www.example.net" and the
- following response is returned to
- the <acronym>BIND</acronym> 9 server
+ following response were returned to
+ the <acronym>BIND</acronym> 9 server:
</para>
<programlisting>www.example.net. A 192.0.2.2</programlisting>
<para>
- it will be accepted since the owner name "www.example.net"
+ it would be accepted, since the owner name "www.example.net"
matches the <command>except-from</command> element,
"example.net".
</para>
<para>
Note that this is not really an attack on the DNS per se.
- In fact, there is nothing wrong for an "external" name to
- be mapped to your "internal" IP address or domain name
- from the DNS point of view.
- It might actually be provided for a legitimate purpose,
+ In fact, there is nothing wrong with having an "external" name
+ mapped to an "internal" IP address or domain name
+ from the DNS point of view;
+ it might actually be provided for a legitimate purpose,
such as for debugging.
As long as the mapping is provided by the correct owner,
- it is not possible or does not make sense to detect
- whether the intent of the mapping is legitimate or not
+ it either is not possible or does not make sense to detect
+ whether the intent of the mapping is legitimate
within the DNS.
The "rebinding" attack must primarily be protected at the
application that uses the DNS.
all possible applications at once.
This filtering feature is provided only to help such an
operational environment;
- it is generally discouraged to turn it on unless you are
- very sure you have no other choice and the attack is a
- real threat for your applications.
+ turning it on is generally discouraged unless there is
+ no other choice and the attack is a
+ real threat to applications.
</para>
<para>
- Care should be particularly taken if you want to use this
+ Care should be particularly taken if using this
option for addresses within 127.0.0.0/8.
- These addresses are obviously "internal", but many
+ These addresses are obviously "internal," but many
applications conventionally rely on a DNS mapping from
some name to such an address.
Filtering out DNS records containing this address
<para>
<acronym>BIND</acronym> 9 includes a limited
mechanism to modify DNS responses for requests
- analogous to email anti-spam DNS blacklists.
+ analogous to email anti-spam DNS rejection lists.
Responses can be changed to deny the existence of domains (NXDOMAIN),
deny the existence of IP addresses for domains (NODATA),
or contain other IP addresses or data.
<para>
Response policy zones are named in the
<command>response-policy</command> option for the view or among the
- global options if there is no response-policy option for the view.
+ global options if there is no <command>response-policy</command> option for the view.
Response policy zones are ordinary DNS zones containing RRsets
that can be queried normally if allowed.
It is usually best to restrict those queries with something like
<para>
Rules encoded in response policy zones are processed after
- <link linkend="access_control">Access Control Lists
+ those defined in <link linkend="access_control">Access Control Lists
(ACLs)</link>. All queries from clients which are not
- permitted access to the resolver will be answered with a
+ permitted access to the resolver are answered with a
status code of REFUSED, regardless of configured RPZ rules.
</para>
DNS client.
Client IP address triggers are encoded in records that have
owner names that are subdomains of
- <command>rpz-client-ip</command> relativized to the
- policy zone origin name
+ <command>rpz-client-ip</command>, relativized to the
+ policy zone origin name,
and encode an address or address block.
IPv4 addresses are represented as
<userinput>prefixlength.B4.B3.B2.B1.rpz-client-ip</userinput>.
The IPv4 prefix length must be between 1 and 32.
- All four bytes, B4, B3, B2, and B1, must be present.
+ All four bytes - B4, B3, B2, and B1 - must be present.
B4 is the decimal value of the least significant byte of the
IPv4 address as in IN-ADDR.ARPA.
</para>
IPv6 addresses are encoded in a format similar
to the standard IPv6 text representation,
<userinput>prefixlength.W8.W7.W6.W5.W4.W3.W2.W1.rpz-client-ip</userinput>.
- Each of W8,...,W1 is a one to four digit hexadecimal number
+ Each of W8,...,W1 is a one- to four-digit hexadecimal number
representing 16 bits of the IPv6 address as in the standard
text representation of IPv6 addresses, but reversed as in
IP6.ARPA. (Note that this representation of IPv6
address is different from IP6.ARPA where each hex
digit occupies a label.)
All 8 words must be present except when one set of consecutive
- zero words is replaced with <userinput>.zz.</userinput>
+ zero words is replaced with <userinput>.zz.</userinput>,
analogous to double colons (::) in standard IPv6 text
encodings.
The IPv6 prefix length must be between 1 and 128.
<para>
IP triggers are IP addresses in an
A or AAAA record in the ANSWER section of a response.
- They are encoded like client-IP triggers except as
+ They are encoded like client-IP triggers, except as
subdomains of <command>rpz-ip</command>.
</para>
</listitem>
<para>
NSDNAME triggers match names of authoritative servers
for the query name, a parent of the query name, a CNAME for
- query name, or a parent of a CNAME.
+ the query name, or a parent of a CNAME.
They are encoded as subdomains of
- <command>rpz-nsdname</command> relativized
+ <command>rpz-nsdname</command>, relativized
to the RPZ origin name.
NSIP triggers match IP addresses in A and
AAAA RRsets for domains that can be checked against NSDNAME
- policy records.
+ policy records. The
+ <command>nsdname-enable</command> phrase turns NSDNAME
+ triggers off or on for a single policy zone or for all
+ zones.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ If authoritative nameservers for the query name are not
+ yet known, <command>named</command> recursively
+ looks up the authoritative servers for the query name
+ before applying an RPZ-NSDNAME rule,
+ which can cause a processing delay. To speed up
+ processing at the cost of precision, the
+ <command>nsdname-wait-recurse</command> option
+ can be used; when set to <userinput>no</userinput>,
+ RPZ-NSDNAME rules are only applied when authoritative
+ servers for the query name have already been looked up and
+ cached. If authoritative servers for the query name
+ are not in the cache, the RPZ-NSDNAME rule is
+ ignored, but the authoritative servers for the query name
+ are looked up in the background and the rule is
+ applied to subsequent queries. The default is
+ <userinput>yes</userinput>, meaning RPZ-NSDNAME
+ rules are always applied, even if authoritative
+ servers for the query name need to be looked up first.
</para>
</listitem>
</varlistentry>
NSDNAME and NSIP triggers are checked only for names with at
least <command>min-ns-dots</command> dots.
The default value of <command>min-ns-dots</command> is
- 1, to exclude top level domains.
+ 1, to exclude top-level domains.
</para>
<para>
If a name server's IP address is not yet known,
- <command>named</command> will recursively look up
- the IP address before applying an RPZ-NSIP rule.
- This can cause a processing delay. To speed up
+ <command>named</command> recursively looks up
+ the IP address before applying an RPZ-NSIP rule,
+ which can cause a processing delay. To speed up
processing at the cost of precision, the
<command>nsip-wait-recurse</command> option
can be used: when set to <userinput>no</userinput>,
- RPZ-NSIP rules will only be applied when a name
- servers's IP address has already been looked up and
+ RPZ-NSIP rules are only applied when a name
+ server's IP address has already been looked up and
cached. If a server's IP address is not in the
- cache, then the RPZ-NSIP rule will be ignored,
- but the address will be looked up in the
- background, and the rule will be applied
+ cache, the RPZ-NSIP rule is ignored,
+ but the address is looked up in the
+ background and the rule is applied
to subsequent queries. The default is
<userinput>yes</userinput>, meaning RPZ-NSIP
- rules should always be applied even if an
+ rules are always applied, even if an
address needs to be looked up first.
</para>
</listitem>
Because DNS responses are rewritten according to at most one
policy record, a single record encoding an action (other than
<command>DISABLED</command> actions) must be chosen.
- Triggers or the records that encode them are chosen for the
+ Triggers, or the records that encode them, are chosen for
rewriting in the following order:
<orderedlist inheritnum="ignore" continuation="restarts">
<listitem>Choose the triggered record in the zone that appears
</para>
<para>
- RPZ record sets are any types of DNS record except
- DNAME or DNSSEC that encode actions or responses to
+ RPZ record sets are any types of DNS record, except
+ DNAME or DNSSEC, that encode actions or responses to
individual queries.
Any of the policies can be used with any of the triggers.
For example, while the <command>TCP-only</command> policy is
<term><command>PASSTHRU</command></term>
<listitem>
<para>
- The whitelist policy is specified
+ The auto-acceptance policy is specified
by a CNAME whose target is <command>rpz-passthru</command>.
It causes the response to not be rewritten
and is most often used to "poke holes" in policies for
<term><command>DROP</command></term>
<listitem>
<para>
- The blacklist policy is specified
+ The auto-rejection policy is specified
by a CNAME whose target is <command>rpz-drop</command>.
It causes the response to be discarded.
Nothing is sent to the DNS client.
<term><command>NXDOMAIN</command></term>
<listitem>
<para>
- The domain undefined response is encoded
+ The "domain undefined" response is encoded
by a CNAME whose target is the root domain (.)
</para>
</listitem>
<term><command>NODATA</command></term>
<listitem>
<para>
- The empty set of resource records is specified by
+ The empty set of resource records is specified by a
CNAME whose target is the wildcard top-level
- domain (*.).
+ domain (<literal>*.</literal>).
It rewrites the response to NODATA or ANCOUNT=0.
</para>
</listitem>
<para>
A special form of local data is a CNAME whose target is a
wildcard such as *.example.com.
- It is used as if were an ordinary CNAME after the asterisk (*)
+ It is used as if an ordinary CNAME after the asterisk (*)
has been replaced with the query name.
- The purpose for this special form is query logging in the
- walled garden's authority DNS server.
+ This special form is useful for query logging in the
+ walled garden's authoritative DNS server.
</para>
</listitem>
</varlistentry>
The testing override policy causes policy zone records to do
nothing but log what they would have done if the
policy zone were not disabled.
- The response to the DNS query will be written (or not)
+ The response to the DNS query is written (or not)
according to any triggered policy records that are not
disabled.
Disabled policy zones should appear first,
- because they will often not be logged
- if a higher precedence trigger is found first.
+ because they are often not logged
+ if a higher-precedence trigger is found first.
</para>
</listitem>
</varlistentry>
<term><command>NODATA</command></term>
<listitem>
<para>
- override with the corresponding per-record policy.
+ each override the corresponding per-record policy.
</para>
</listitem>
</varlistentry>
<para>
By default, the actions encoded in a response policy zone
are applied only to queries that ask for recursion (RD=1).
- That default can be changed for a single policy zone or
- all response policy zones in a view
+ That default can be changed for a single policy zone, or for
+ all response policy zones in a view,
with a <command>recursive-only no</command> clause.
This feature is useful for serving the same zone files
both inside and outside an RFC 1918 cloud and using RPZ to
<para>
Also by default, RPZ actions are applied only to DNS requests
that either do not request DNSSEC metadata (DO=0) or when no
- DNSSEC records are available for request name in the original
+ DNSSEC records are available for the requested name in the original
zone (not the response policy zone). This default can be
changed for all response policy zones in a view with a
<command>break-dnssec yes</command> clause. In that case, RPZ
</para>
<para>
- No DNS records are needed for a QNAME or Client-IP trigger.
- The name or IP address itself is sufficient,
+ No DNS records are needed for a QNAME or Client-IP trigger;
+ the name or IP address itself is sufficient,
so in principle the query name need not be recursively resolved.
However, not resolving the requested
- name can leak the fact that response policy rewriting is in use
- and that the name is listed in a policy zone to operators of
+ name can leak the fact that response policy rewriting is in use,
+ and that the name is listed in a policy zone, to operators of
servers for listed names. To prevent that information leak, by
default any recursion needed for a request is done before any
policy triggers are considered. Because listed domains often
- have slow authoritative servers, this default behavior can cost
+ have slow authoritative servers, this behavior can cost
significant time.
The <command>qname-wait-recurse no</command> option
overrides that default behavior when recursion cannot
change a non-error response.
The option does not affect QNAME or client-IP triggers
in policy zones listed
- after other zones containing IP, NSIP and NSDNAME triggers, because
+ after other zones containing IP, NSIP, and NSDNAME triggers, because
those may depend on the A, AAAA, and NS records that would be
found during recursive resolution. It also does not affect
DNSSEC requests (DO=1) unless <command>break-dnssec yes</command>
- is in use, because the response would depend on whether or not
+ is in use, because the response would depend on whether
RRSIG records were found during resolution.
Using this option can cause error responses such as SERVFAIL to
appear to be rewritten, since no recursion is being done to
<para>
The TTL of a record modified by RPZ policies is set from the
- TTL of the relevant record in policy zone. It is then limited
+ TTL of the relevant record in the policy zone. It is then limited
to a maximum value.
The <command>max-policy-ttl</command> clause changes the
- maximum seconds from its default of 5.
+ maximum number of seconds from its default of 5.
</para>
<para>
- For example, you might use this option statement
+ For example, an administrator might use this option statement:
</para>
<programlisting> response-policy { zone "badlist"; };</programlisting>
<para>
- and this zone statement
+ and this zone statement:
</para>
<programlisting> zone "badlist" {type master; file "master/badlist"; allow-query {none;}; };</programlisting>
<para>
- with this zone file
+ with this zone file:
</para>
<programlisting>$TTL 1H
@ SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
ns.domain.com.rpz-nsdname CNAME .
48.zz.2.2001.rpz-nsip CNAME .
-; blacklist and whitelist some DNS clients
+; auto-reject and auto-accept some DNS clients
112.zz.2001.rpz-client-ip CNAME rpz-drop.
8.0.0.0.127.rpz-client-ip CNAME rpz-drop.
perform one to four additional database lookups before a
query can be answered.
For example, a DNS server with four policy zones, each with all
- four kinds of response triggers, QNAME, IP, NSIP, and
- NSDNAME, requires a total of 17 times as many database
+ four kinds of response triggers (QNAME, IP, NSIP, and
+ NSDNAME), requires a total of 17 times as many database
lookups as a similar DNS server with no response policy zones.
- A <acronym>BIND9</acronym> server with adequate memory and one
+ A <acronym>BIND</acronym> 9 server with adequate memory and one
response policy zone with QNAME and IP triggers might achieve a
- maximum queries-per-second rate about 20% lower.
+ maximum queries-per-second (QPS) rate about 20% lower.
A server with four response policy zones with QNAME and IP
triggers might have a maximum QPS rate about 50% lower.
</para>
<section xml:id="rrl"><info><title>Response Rate Limiting</title></info>
<para>
- Excessive almost identical UDP <emphasis>responses</emphasis>
+ Excessive, almost identical UDP <emphasis>responses</emphasis>
can be controlled by configuring a
<command>rate-limit</command> clause in an
<command>options</command> or <command>view</command> statement.
This mechanism keeps authoritative BIND 9 from being used
- in amplifying reflection denial of service (DoS) attacks.
- Short truncated (TC=1) responses can be sent to provide
+ to amplify reflection denial of service (DoS) attacks.
+ Short, truncated (TC=1) responses can be sent to provide
rate-limited responses to legitimate clients within
a range of forged, attacked IP addresses.
- Legitimate clients react to dropped or truncated response
- by retrying with UDP or with TCP respectively.
+ Legitimate clients react to dropped or truncated responses
+ by retrying with UDP or with TCP, respectively.
</para>
<para>
This mechanism is intended for authoritative DNS servers.
- It can be used on recursive servers but can slow
+ It can be used on recursive servers, but can slow
applications such as SMTP servers (mail receivers) and
HTTP clients (web browsers) that repeatedly request the
same domains.
<para>
Response rate limiting uses a "credit" or "token bucket" scheme.
Each combination of identical response and client
- has a conceptual account that earns a specified number
+ has a conceptual "account" that earns a specified number
of credits every second.
A prospective response debits its account by one.
Responses are dropped or truncated
while the account is negative.
Responses are tracked within a rolling window of time
- which defaults to 15 seconds, but can be configured with
+ which defaults to 15 seconds, but which can be configured with
the <command>window</command> option to any value from
1 to 3600 seconds (1 hour).
The account cannot become more positive than
or more negative than <command>window</command>
times the per-second limit.
When the specified number of credits for a class of
- responses is set to 0, those responses are not rate limited.
+ responses is set to 0, those responses are not rate-limited.
</para>
<para>
for rate limiting are not simplistic.
All responses to an address block are counted as if to a
single client.
- The prefix lengths of addresses blocks are
+ The prefix lengths of address blocks are
specified with <command>ipv4-prefix-length</command> (default 24)
and <command>ipv6-prefix-length</command> (default 56).
</para>
This controls some attacks using random names, but
can be relaxed or turned off (set to 0)
on servers that expect many legitimate
- NXDOMAIN responses, such as from anti-spam blacklists.
+ NXDOMAIN responses, such as from anti-spam rejection lists.
Referrals or delegations to the server of a given
domain are identical and are limited by
<command>referrals-per-second</command>
Setting <command>slip</command> to 2 (its default) causes every
other UDP request to be answered with a small truncated (TC=1)
response.
- The small size and reduced frequency, and so lack of
+ The small size and reduced frequency, and resulting lack of
amplification, of "slipped" responses make them unattractive
for reflection DoS attacks.
<command>slip</command> must be between 0 and 10.
- A value of 0 does not "slip":
- no truncated responses are sent due to rate limiting,
- all responses are dropped.
+ A value of 0 does not "slip";
+ no truncated responses are sent due to rate limiting.
+ Rather, all responses are dropped.
A value of 1 causes every response to slip;
- values between 2 and 10 cause every n'th response to slip.
- Some error responses including REFUSED and SERVFAIL
+ values between 2 and 10 cause every nth response to slip.
+ Some error responses, including REFUSED and SERVFAIL,
cannot be replaced with truncated responses and are instead
leaked at the <command>slip</command> rate.
</para>
<para>
- (NOTE: Dropped responses from an authoritative server may
+ (Note: dropped responses from an authoritative server may
reduce the difficulty of a third party successfully forging
a response to a recursive resolver. The best security
against forged responses is for authoritative operators
</para>
<para>
- When the approximate query per second rate exceeds
+ When the approximate query-per-second rate exceeds
the <command>qps-scale</command> value,
- then the <command>responses-per-second</command>,
+ the <command>responses-per-second</command>,
<command>errors-per-second</command>,
- <command>nxdomains-per-second</command> and
+ <command>nxdomains-per-second</command>, and
<command>all-per-second</command> values are reduced by the
ratio of the current rate to the <command>qps-scale</command> value.
This feature can tighten defenses during attacks.
a total query rate of 1000 queries/second for all queries from
all DNS clients including via TCP,
then the effective responses/second limit changes to
- (250/1000)*20 or 5.
+ (250/1000)*20, or 5.
Responses sent via TCP are not limited
- but are counted to compute the query per second rate.
+ but are counted to compute the query-per-second rate.
</para>
<para>
Communities of DNS clients can be given their own parameters or no
rate limiting by putting
<command>rate-limit</command> statements in <command>view</command>
- statements instead of the global <command>option</command>
+ statements instead of in the global <command>option</command>
statement.
A <command>rate-limit</command> statement in a view replaces,
- rather than supplementing, a <command>rate-limit</command>
+ rather than supplements, a <command>rate-limit</command>
statement among the main options.
DNS clients within a view can be exempted from rate limits
with the <command>exempt-clients</command> clause.
limiting is unlike the rate limiting provided by
<command>responses-per-second</command>,
<command>errors-per-second</command>, and
- <command>nxdomains-per-second</command> on a DNS server
+ <command>nxdomains-per-second</command> on a DNS server,
which are often invisible to the victim of a DNS
reflection attack. Unless the forged requests of the
attack are the same as the legitimate requests of the
server for NS, PTR, A, and AAAA records as the incoming
SMTP/TCP/IP connection is considered. The SMTP server
can need additional NS, A, AAAA, MX, TXT, and SPF records
- as it considers the STMP <command>Mail From</command>
+ as it considers the SMTP <command>Mail From</command>
command. Web browsers often repeatedly resolve the
- same names that are repeated in HTML <IMG> tags
+ same names that are duplicated in HTML <IMG> tags
in a page. <command>all-per-second</command> is similar
- to the rate limiting offered by firewalls but often
+ to the rate limiting offered by firewalls but is often
inferior. Attacks that justify ignoring the contents
of DNS responses are likely to be attacks on the DNS
server itself. They usually should be discarded before
<para>
The maximum size of the table used to track requests and
- rate limit responses is set with <command>max-table-size</command>.
+ rate-limit responses is set with <command>max-table-size</command>.
Each entry in the table is between 40 and 80 bytes.
The table needs approximately as many entries as the number
of requests received per second.
</para>
<para>
- Use <command>log-only yes</command> to test rate limiting parameters
+ Use <command>log-only yes</command> to test rate-limiting parameters
without actually dropping any requests.
</para>
</para>
</section>
- <section title="NXDOMAIN Redirection"><info/>
+ <section xml:id="nxdomain_redirect"><info><title>NXDOMAIN Redirection</title></info>
<para>
- Named supports NXDOMAIN redirection via two methods:
+ <command>named</command> supports NXDOMAIN redirection via two methods:
<itemizedlist>
<listitem>Redirect zone <xref linkend="zone_statement_grammar"/></listitem>
<listitem>Redirect namespace</listitem>
</itemizedlist>
</para>
<para>
- With both methods when named gets a NXDOMAIN response
+ With either method, when <command>named</command> gets an NXDOMAIN response
it examines a separate namespace to see if the NXDOMAIN
response should be replaced with an alternative response.
</para>
</para>
<para>
With a redirect namespace (<command>option { nxdomain-redirect
- <suffix> };</command>) the data used to replace the
+ <suffix> };</command>), the data used to replace the
NXDOMAIN is part of the normal namespace and is looked up by
appending the specified suffix to the original query name.
This roughly doubles the cache required to process NXDOMAIN
- responses as you have the original NXDOMAIN response and
- the replacement data or a NXDOMAIN indicating that there
- is no replacement.
+ responses, as both the original NXDOMAIN response and
+ the replacement data (or a NXDOMAIN indicating that there
+ is no replacement) must be stored.
</para>
<para>
If both a redirect zone and a redirect namespace are configured,
to be associated with a remote name server. If a prefix length is
specified, then a range of servers is covered. Only the most
specific
- server clause applies regardless of the order in
+ server clause applies, regardless of the order in
<filename>named.conf</filename>.
</para>
</para>
<para>
- If you discover that a remote server is giving out bad data,
- marking it as bogus will prevent further queries to it. The
+ If a remote server is giving out bad data,
+ marking it as bogus prevents further queries to it. The
default
value of <command>bogus</command> is <command>no</command>.
</para>
<para>
The <command>provide-ixfr</command> clause determines
whether
- the local server, acting as master, will respond with an
+ the local server, acting as primary, responds with an
incremental
- zone transfer when the given remote server, a slave, requests it.
+ zone transfer when the given remote server, a secondary, requests it.
If set to <command>yes</command>, incremental transfer
- will be provided
+ is provided
whenever possible. If set to <command>no</command>,
all transfers
- to the remote server will be non-incremental. If not set, the
+ to the remote server are non-incremental. If not set, the
value
of the <command>provide-ixfr</command> option in the
view or
<para>
The <command>request-ixfr</command> clause determines
whether
- the local server, acting as a slave, will request incremental zone
- transfers from the given remote server, a master. If not set, the
+ the local server, acting as a secondary, requests incremental zone
+ transfers from the given remote server, a primary. If not set, the
value of the <command>request-ixfr</command> option in
the view or global options block is used as a default. It may
- also be set in the zone block and, if set there, it will
- override the global or view setting for that zone.
+ also be set in the zone block; if set there, it
+ overrides the global or view setting for that zone.
</para>
<para>
- IXFR requests to servers that do not support IXFR will
+ IXFR requests to servers that do not support IXFR
automatically
fall back to AXFR. Therefore, there is no need to manually list
which servers support IXFR and which ones do not; the global
The purpose of the <command>provide-ixfr</command> and
<command>request-ixfr</command> clauses is
to make it possible to disable the use of IXFR even when both
- master
- and slave claim to support it, for example if one of the servers
+ primary
+ and secondary claim to support it: for example, if one of the servers
is buggy and crashes or corrupts data when IXFR is used.
</para>
<para>
The <command>request-expire</command> clause determines
- whether the local server, when acting as a slave, will
- request the EDNS EXPIRE value. The EDNS EXPIRE value
- indicates the remaining time before the zone data will
- expire and need to be be refreshed. This is used
+ whether the local server, when acting as a secondary,
+ requests the EDNS EXPIRE value. The EDNS EXPIRE value
+ indicates the remaining time before the zone data
+ expires and needs to be refreshed. This is used
when a secondary server transfers a zone from another
secondary server; when transferring from the primary, the
expiration timer is set from the EXPIRE field of the SOA
<para>
The <command>edns</command> clause determines whether
- the local server will attempt to use EDNS when communicating
+ the local server attempts to use EDNS when communicating
with the remote server. The default is <command>yes</command>.
</para>
The <command>edns-udp-size</command> option sets the
EDNS UDP size that is advertised by <command>named</command>
when querying the remote server. Valid values are 512
- to 4096 bytes (values outside this range will be silently
- adjusted to the nearest value within it). This option
- is useful when you wish to advertise a different value
- to this server than the value you advertise globally,
+ to 4096 bytes; values outside this range are silently
+ adjusted to the nearest value within it. This option
+ is useful when advertising a different value
+ to this server than the value advertised globally:
for example, when there is a firewall at the remote
- site that is blocking large replies. (Note: Currently,
+ site that is blocking large replies. Note: currently,
this sets a single UDP size for all packets sent to the
- server; <command>named</command> will not deviate from
+ server; <command>named</command> does not deviate from
this value. This differs from the behavior of
<command>edns-udp-size</command> in <command>options</command>
or <command>view</command> statements, where it specifies
a maximum value. The <command>server</command> statement
behavior may be brought into conformance with the
- <command>options/view</command> behavior in future releases.)
+ <command>options/view</command> behavior in future releases.
</para>
<para>
The <command>edns-version</command> option sets the
- maximum EDNS VERSION that will be sent to the server(s)
+ maximum EDNS VERSION that is sent to the server(s)
by the resolver. The actual EDNS version sent is still
- subject to normal EDNS version negotiation rules (see
+ subject to normal EDNS version-negotiation rules (see
RFC 6891), the maximum EDNS version supported by the
server, and any other heuristics that indicate that a
lower version should be sent. This option is intended
to be used when a remote server reacts badly to a given
EDNS version or higher; it should be set to the highest
version the remote server is known to support. Valid
- values are 0 to 255; higher values will be silently
- adjusted. This option will not be needed until higher
+ values are 0 to 255; higher values are silently
+ adjusted. This option is not needed until higher
EDNS versions than 0 are in use.
</para>
<para>
The <command>max-udp-size</command> option sets the
maximum EDNS UDP message size <command>named</command>
- will send. Valid values are 512 to 4096 bytes (values
- outside this range will be silently adjusted). This
- option is useful when you know that there is a firewall
+ sends. Valid values are 512 to 4096 bytes; values
+ outside this range are silently adjusted. This
+ option is useful when there is a firewall
that is blocking large replies from <command>named</command>.
</para>
<para>
The server supports two zone transfer methods. The first, <command>one-answer</command>,
uses one DNS message per resource record transferred. <command>many-answers</command> packs
- as many resource records as possible into a message. <command>many-answers</command> is
- more efficient, but is only known to be understood by <acronym>BIND</acronym> 9, <acronym>BIND</acronym>
- 8.x, and patched versions of <acronym>BIND</acronym>
- 4.9.5. You can specify which method
- to use for a server with the <command>transfer-format</command> option.
- If <command>transfer-format</command> is not
- specified, the <command>transfer-format</command>
+ as many resource records as possible into a single message, which is
+ more efficient. It is possible to specify which method
+ to use for a server via the <command>transfer-format</command> option;
+ If not set there, the <command>transfer-format</command>
specified
- by the <command>options</command> statement will be
+ by the <command>options</command> statement is
used.
</para>
to be used for transaction security (TSIG, <xref linkend="tsig"/>)
when talking to the remote server.
When a request is sent to the remote server, a request signature
- will be generated using the key specified here and appended to the
+ is generated using the key specified here and appended to the
message. A request originating from the remote server is not
required
to be signed by this key.
The <command>transfer-source</command> and
<command>transfer-source-v6</command> clauses specify
the IPv4 and IPv6 source
- address to be used for zone transfer with the remote server,
- respectively.
+ address, respectively, to be used for zone transfer with the remote server.
For an IPv4 remote server, only <command>transfer-source</command> can
be specified.
Similarly, for an IPv6 remote server, only
<para>
The <command>notify-source</command> and
<command>notify-source-v6</command> clauses specify the
- IPv4 and IPv6 source address to be used for notify
- messages sent to remote servers, respectively. For an
+ IPv4 and IPv6 source address, respectively, to be used for notify
+ messages sent to remote servers. For an
IPv4 remote server, only <command>notify-source</command>
can be specified. Similarly, for an IPv6 remote server,
only <command>notify-source-v6</command> can be specified.
<para>
The <command>query-source</command> and
<command>query-source-v6</command> clauses specify the
- IPv4 and IPv6 source address to be used for queries
- sent to remote servers, respectively. For an IPv4
+ IPv4 and IPv6 source address, respectively, to be used for queries
+ sent to remote servers. For an IPv4
remote server, only <command>query-source</command> can
be specified. Similarly, for an IPv6 remote server,
only <command>query-source-v6</command> can be specified.
<para>
The <command>request-nsid</command> clause determines
- whether the local server will add a NSID EDNS option
+ whether the local server adds an NSID EDNS option
to requests sent to the server. This overrides
<command>request-nsid</command> set at the view or
option level.
<para>
The <command>send-cookie</command> clause determines
- whether the local server will add a COOKIE EDNS option
+ whether the local server adds a COOKIE EDNS option
to requests sent to the server. This overrides
<command>send-cookie</command> set at the view or
option level. The <command>named</command> server may
<para>
The <command>statistics-channels</command> statement
declares communication channels to be used by system
- administrators to get access to statistics information of
+ administrators to get access to statistics information on
the name server.
</para>
<para>
- This statement intends to be flexible to support multiple
+ This statement is intended to be flexible to support multiple
communication protocols in the future, but currently only
HTTP access is supported.
It requires that BIND 9 be compiled with libxml2 and/or
json-c (also known as libjson0); the
<command>statistics-channels</command> statement is
still accepted even if it is built without the library,
- but any HTTP access will fail with an error.
+ but any HTTP access fails with an error.
</para>
<para>
specified <command>ip_addr</command>, which can be an IPv4 or IPv6
address. An <command>ip_addr</command> of <literal>*</literal>
(asterisk) is
- interpreted as the IPv4 wildcard address; connections will be
+ interpreted as the IPv4 wildcard address; connections are
accepted on any of the system's IPv4 addresses.
To listen on the IPv6 wildcard address,
use an <command>ip_addr</command> of <literal>::</literal>.
<para>
If no port is specified, port 80 is used for HTTP channels.
- The asterisk "<literal>*</literal>" cannot be used for
+ The asterisk (<literal>*</literal>) cannot be used for
<command>ip_port</command>.
</para>
<para>
- The attempt of opening a statistics channel is
+ Attempts to open a statistics channel are
restricted by the optional <command>allow</command> clause.
Connections to the statistics channel are permitted based on the
<command>address_match_list</command>.
<para>
If no <command>statistics-channels</command> statement is present,
- <command>named</command> will not open any communication channels.
+ <command>named</command> does not open any communication channels.
</para>
<para>
- The statistics are available in various formats and views
+ The statistics are available in various formats and views,
depending on the URI used to access them. For example, if
the statistics channel is configured to listen on 127.0.0.1
port 8888, then the statistics are accessible in XML format at
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://127.0.0.1:8888/">http://127.0.0.1:8888/</link> or
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://127.0.0.1:8888/xml">http://127.0.0.1:8888/xml</link>. A CSS file is
- included which can format the XML statistics into tables
+ included, which can format the XML statistics into tables
when viewed with a stylesheet-capable browser, and into
charts and graphs using the Google Charts API when using a
- javascript-capable browser.
+ JavaScript-capable browser.
</para>
<para>
cannot be securely obtained through DNS, either because
it is the DNS root zone or because its parent zone is
unsigned. Once a key has been configured as a trusted
- key, it is treated as if it had been validated and
+ key, it is treated as if it has been validated and
proven secure. The resolver attempts DNSSEC validation
on all DNS data in subdomains of a security root.
</para>
<para>
All keys (and corresponding zones) listed in
<command>trusted-keys</command> are deemed to exist regardless
- of what parent zones say. Similarly for all keys listed in
- <command>trusted-keys</command> only those keys are
+ of what parent zones say. Similarly, for all keys listed in
+ <command>trusted-keys</command>, only those keys are
used to validate the DNSKEY RRset. The parent's DS RRset
- will not be used.
+ is not used.
</para>
<para>
The <command>trusted-keys</command> statement can contain
multiple key entries, each consisting of the key's
- domain name, flags, protocol, algorithm, and the Base64
+ domain name, flags, protocol, and algorithm, and the Base64
representation of the key data.
- Spaces, tabs, newlines and carriage returns are ignored
- in the key data, so the configuration may be split up into
+ Spaces, tabs, newlines, and carriage returns are ignored
+ in the key data, so the configuration may be split into
multiple lines.
</para>
<para>
<command>trusted-keys</command> may be set at the top level
of <filename>named.conf</filename> or within a view. If it is
- set in both places, they are additive: keys defined at the top
+ set in both places, they are additive; keys defined at the top
level are inherited by all views, but keys defined in a view
are only used within that view.
</para>
The <command>managed-keys</command> statement, like
<command>trusted-keys</command>, defines DNSSEC
security roots. The difference is that
- <command>managed-keys</command> can be kept up to date
+ <command>managed-keys</command> can be kept up-to-date
automatically, without intervention from the resolver
operator.
</para>
key was compromised, and the zone owner had to revoke and
replace the key. A resolver which had the old key in a
<command>trusted-keys</command> statement would be
- unable to validate this zone any longer; it would
+ unable to validate this zone; it would
reply with a SERVFAIL response code. This would
- continue until the resolver operator had updated the
+ continue until the resolver operator updated the
<command>trusted-keys</command> statement with the new key.
</para>
<para>
If, however, the zone were listed in a
- <command>managed-keys</command> statement instead, then the
+ <command>managed-keys</command> statement instead, the
zone owner could add a "stand-by" key to the zone in advance.
<command>named</command> would store the stand-by key, and
when the original key was revoked, <command>named</command>
would be able to transition smoothly to the new key. It would
- also recognize that the old key had been revoked, and cease
+ also recognize that the old key had been revoked and cease
using that key to validate answers, minimizing the damage that
the compromised key could do.
</para>
</para>
<para>
Consequently, a <command>managed-keys</command> statement
- appears similar to a <command>trusted-keys</command>, differing
- in the presence of the second field, containing the keyword
+ appears similar to a <command>trusted-keys</command> statement, differing
+ by the presence of the second field, which contains the keyword
<literal>initial-key</literal>. The difference is, whereas the
keys listed in a <command>trusted-keys</command> continue to be
trusted until they are removed from
<filename>named.conf</filename>, an initializing key listed
in a <command>managed-keys</command> statement is only trusted
<emphasis>once</emphasis>: for as long as it takes to load the
- managed key database and start the RFC 5011 key maintenance
+ managed-key database and start the RFC 5011 key-maintenance
process.
</para>
<para>
DNSKEY RRset directly from the zone apex, and validates it
using the key specified in the <command>managed-keys</command>
statement. If the DNSKEY RRset is validly signed, then it is
- used as the basis for a new managed keys database.
+ used as the basis for a new managed-keys database.
</para>
<para>
From that point on, whenever <command>named</command> runs, it
sees the <command>managed-keys</command> statement, checks to
make sure RFC 5011 key maintenance has already been initialized
- for the specified domain, and if so, it simply moves on. The
+ for the specified domain, and if so, simply moves on. The
key specified in the <command>managed-keys</command>
- statement is not used to validate answers; it has been
- superseded by the key or keys stored in the managed keys database.
+ statement is not used to validate answers; it is
+ superseded by the key or keys stored in the managed-keys database.
</para>
<para>
The next time <command>named</command> runs after a name
has been <emphasis>removed</emphasis> from the
<command>managed-keys</command> statement, the corresponding
- zone will be removed from the managed keys database,
- and RFC 5011 key maintenance will no longer be used for that
+ zone is removed from the managed-keys database,
+ and RFC 5011 key maintenance is no longer used for that
domain.
</para>
<para>
- In the current implementation, the managed keys database
+ In the current implementation, the managed-keys database
is stored as a master-format zone file.
</para>
<para>
On servers which do not use views, this file is named
<filename>managed-keys.bind</filename>. When views are in
- use, there will be a separate managed keys database for each
- view; the filename will be the view name (or, if a view name
+ use, there is a separate managed-keys database for each
+ view; the filename is the view name (or, if a view name
contains characters which would make it illegal as a filename,
a hash of the view name), followed by
the suffix <filename>.mkeys</filename>.
</para>
<para>
When the key database is changed, the zone is updated.
- As with any other dynamic zone, changes will be written
+ As with any other dynamic zone, changes are written
into a journal file, e.g.,
<filename>managed-keys.bind.jnl</filename> or
<filename>internal.mkeys.jnl</filename>.
- Changes are committed to the master file as soon as
- possible afterward; this will usually occur within 30
- seconds. So, whenever <command>named</command> is using
+ Changes are committed to the zone file as soon as
+ possible afterward, usually within 30
+ seconds. Whenever <command>named</command> is using
automatic key maintenance, the zone file and journal file
can be expected to exist in the working directory.
- (For this reason among others, the working directory
+ (For this reason, among others, the working directory
should be always be writable by <command>named</command>.)
</para>
<para>
If the <command>dnssec-validation</command> option is
set to <userinput>auto</userinput>, <command>named</command>
- will automatically initialize a managed key for the
- root zone. The key that is used to initialize the key
- maintenance process is stored in <filename>bind.keys</filename>;
+ automatically initializes a managed key for the
+ root zone. The key that is used to initialize the
+ key-maintenance process is stored in <filename>bind.keys</filename>;
the location of this file can be overridden with the
<command>bindkeys-file</command> option. As a fallback
in the event no <filename>bind.keys</filename> can be
<para>
Each <command>view</command> statement defines a view
of the
- DNS namespace that will be seen by a subset of clients. A client
+ DNS namespace that is seen by a subset of clients. A client
matches
a view if its source IP address matches the
<varname>address_match_list</varname> of the view's
specified, both
<command>match-clients</command> and <command>match-destinations</command>
default to matching all addresses. In addition to checking IP
- addresses
+ addresses,
<command>match-clients</command> and <command>match-destinations</command>
can also take <command>keys</command> which provide an
mechanism for the
client to select the view. A view can also be specified
as <command>match-recursive-only</command>, which
means that only recursive
- requests from matching clients will match that view.
+ requests from matching clients match that view.
The order of the <command>view</command> statements is
- significant —
- a client request will be resolved in the context of the first
+ significant;
+ a client request is resolved in the context of the first
<command>view</command> that it matches.
</para>
<para>
Zones defined within a <command>view</command>
- statement will
- only be accessible to clients that match the <command>view</command>.
+ statement are
+ only accessible to clients that match the <command>view</command>.
By defining a zone of the same name in multiple views, different
- zone data can be given to different clients, for example,
+ zone data can be given to different clients: for example,
"internal"
and "external" clients in a split DNS setup.
</para>
</para>
<para>
- Views are class specific. If no class is given, class IN
+ Views are class-specific. If no class is given, class IN
is assumed. Note that all non-IN views must contain a hint zone,
since only the IN class has compiled-in default hints.
</para>
the top level of the configuration file are considered to be part
of
this default view, and the <command>options</command>
- statement will
- apply to the default view. If any explicit <command>view</command>
+ statement
+ applies to the default view. If any explicit <command>view</command>
statements are present, all <command>zone</command>
statements must
occur inside <command>view</command> statements.
The <command>type</command> keyword is required
for the <command>zone</command> configuration unless
it is an <command>in-view</command> configuration. Its
- acceptable values include: <varname>delegation-only</varname>,
- <varname>forward</varname>, <varname>hint</varname>,
- <varname>master</varname>, <varname>redirect</varname>,
- <varname>slave</varname>, <varname>static-stub</varname>,
- and <varname>stub</varname>.
+ acceptable values are: <varname>master</varname>,
+ <varname>slave</varname>, <varname>hint</varname>,
+ <varname>stub</varname>, <varname>static-stub</varname>,
+ <varname>forward</varname>, <varname>redirect</varname>,
+ or <varname>delegation-only</varname>.
</para>
+ <note>
+ Later versions of BIND added <command>type primary</command>
+ and <command>type secondary</command> as synonyms for
+ <command>type master</command> and <command>type slave</command>,
+ as those terms are in more common use now. BIND 9.11's
+ configuration syntax predates this change.
+ </note>
<informaltable colsep="0" rowsep="0">
<tgroup cols="2" colsep="0" rowsep="0" tgroupstyle="3Level-table">
<entry colname="2">
<para>
The server has a master copy of the data
- for the zone and will be able to provide authoritative
- answers for
- it.
+ for the zone and is able to provide authoritative
+ answers for it.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- A slave zone is a replica of a master
- zone. The <command>masters</command> list
+ A secondary zone, replicating a primary zone
+ provided by another authoritative server.
+ The <command>masters</command> list
specifies one or more IP addresses
- of master servers that the slave contacts to update
+ of primary servers that the secondary contacts to update
its copy of the zone.
Masters list elements can also be names of other
masters lists.
before the
list of IP addresses, or on a per-server basis after
the IP address.
- Authentication to the master can also be done with
+ Authentication to the primary can also be done with
per-server TSIG keys.
If a file is specified, then the
- replica will be written to this file whenever the zone
+ replica is written to this file whenever the zone
is changed,
and reloaded from this file on a server restart. Use
of a file is
is best to
use a two-level naming scheme for zone filenames. For
example,
- a slave server for the zone <literal>example.com</literal> might place
+ a secondary server for the zone <literal>example.com</literal> might place
the zone contents into a file called
<filename>ex/example.com</filename> where <filename>ex/</filename> is
just the first two letters of the zone name. (Most
operating systems
- behave very slowly if you put 100000 files into
+ behave very slowly if there are 100000 files in
a single directory.)
</para>
</entry>
</row>
+ <row rowsep="0">
+ <entry colname="1">
+ <para>
+ <varname>hint</varname>
+ </para>
+ </entry>
+ <entry colname="2">
+ <para>
+ The initial set of root name servers is
+ specified using a hint zone. When the server starts,
+ it uses
+ the root hints to find a root name server and get the
+ most recent
+ list of root name servers. If no hint zone is
+ specified for class
+ IN, the server uses a compiled-in default set of root
+ servers hints.
+ Classes other than IN have no built-in default hints.
+ </para>
+ </entry>
+ </row>
<row rowsep="0">
<entry colname="1">
<para>
</entry>
<entry colname="2">
<para>
- A stub zone is similar to a slave zone,
+ A stub zone is similar to a secondary zone,
except that it replicates only the NS records of a
- master zone instead
+ primary zone instead
of the entire zone. Stub zones are not a standard part
of the DNS;
they are a feature specific to the <acronym>BIND</acronym> implementation.
</para>
<para>
- Stub zones can be used to eliminate the need for glue
+ Stub zones can be used to eliminate the need for a glue
NS record
- in a parent zone at the expense of maintaining a stub
+ in a parent zone, at the expense of maintaining a stub
zone entry and
a set of name server addresses in <filename>named.conf</filename>.
This usage is not recommended for new configurations,
and BIND 9
supports it only in a limited way.
- In <acronym>BIND</acronym> 4/8, zone
- transfers of a parent zone
- included the NS records from stub children of that
- zone. This meant
- that, in some cases, users could get away with
- configuring child stubs
- only in the master server for the parent zone. <acronym>BIND</acronym>
- 9 never mixes together zone data from different zones
- in this
- way. Therefore, if a <acronym>BIND</acronym> 9 master serving a parent
- zone has child stub zones configured, all the slave
+ If a <acronym>BIND</acronym> 9 primary, serving a parent
+ zone, has child stub zones configured, all the secondary
servers for the
parent zone also need to have the same child stub
zones
</para>
<para>
- Stub zones can also be used as a way of forcing the
+ Stub zones can also be used as a way to force the
resolution
of a given domain to use a particular set of
authoritative servers.
For example, the caching name servers on a private
network using
- RFC1918 addressing may be configured with stub zones
+ RFC 1918 addressing may be configured with stub zones
for
<literal>10.in-addr.arpa</literal>
to use a set of internal name servers as the
A static-stub zone is similar to a stub zone
with the following exceptions:
the zone data is statically configured, rather
- than transferred from a master server;
+ than transferred from a primary server; and
when recursion is necessary for a query that
matches a static-stub zone, the locally
- configured data (nameserver names and glue addresses)
- is always used even if different authoritative
+ configured data (name server names and glue addresses)
+ is always used, even if different authoritative
information is cached.
</para>
<para>
databases by <command>rndc dumpdb -all</command>.
The configured RRs are considered local configuration
parameters rather than public data.
- Non recursive queries (i.e., those with the RD
+ Non-recursive queries (i.e., those with the RD
bit off) to a static-stub zone are therefore
- prohibited and will be responded with REFUSED.
+ prohibited and are responded to with REFUSED.
</para>
<para>
Since the data is statically configured, no
<para>
Each static-stub zone is configured with
internally generated NS and (if necessary)
- glue A or AAAA RRs
+ glue A or AAAA RRs.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- A "forward zone" is a way to configure
+ A forward zone is a way to configure
forwarding on a per-domain basis. A <command>zone</command> statement
of type <command>forward</command> can
contain a <command>forward</command>
and/or <command>forwarders</command>
statement,
- which will apply to queries within the domain given by
+ which applies to queries within the domain given by
the zone
name. If no <command>forwarders</command>
- statement is present or
+ statement is present, or
an empty list for <command>forwarders</command> is given, then no
- forwarding will be done for the domain, canceling the
+ forwarding is done for the domain, canceling the
effects of
- any forwarders in the <command>options</command> statement. Thus
- if you want to use this type of zone to change the
+ any forwarders in the <command>options</command> statement. Thus,
+ to use this type of zone to change the
behavior of the
global <command>forward</command> option
(that is, "forward first"
- to, then "forward only", or vice versa, but want to
+ to, then "forward only", or vice versa), but
use the same
- servers as set globally) you need to re-specify the
+ servers as set globally, re-specify the
global forwarders.
</para>
</entry>
</row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- <varname>hint</varname>
- </para>
- </entry>
- <entry colname="2">
- <para>
- The initial set of root name servers is
- specified using a "hint zone". When the server starts
- up, it uses
- the root hints to find a root name server and get the
- most recent
- list of root name servers. If no hint zone is
- specified for class
- IN, the server uses a compiled-in default set of root
- servers hints.
- Classes other than IN have no built-in defaults hints.
- </para>
- </entry>
- </row>
<row rowsep="0">
<entry colname="1">
<para>
</para>
<para>
If the client has requested DNSSEC records (DO=1) and
- the NXDOMAIN response is signed then no substitution
- will occur.
+ the NXDOMAIN response is signed, no substitution
+ occurs.
</para>
<para>
To redirect all NXDOMAIN responses to
100.100.100.2 and
- 2001:ffff:ffff::100.100.100.2, one would
- configure a type redirect zone named ".",
+ 2001:ffff:ffff::100.100.100.2,
+ configure a type <varname>redirect</varname> zone named ".",
with the zone file containing wildcard records
that point to the desired addresses:
- <literal>"*. IN A 100.100.100.2"</literal>
+ <literal>*. IN A 100.100.100.2</literal>
and
- <literal>"*. IN AAAA 2001:ffff:ffff::100.100.100.2"</literal>.
+ <literal>*. IN AAAA 2001:ffff:ffff::100.100.100.2</literal>.
</para>
<para>
- To redirect all Spanish names (under .ES) one
- would use similar entries but with the names
+ As another example, to redirect all Spanish names (under .ES),
+ use similar entries but with the names
"*.ES." instead of "*.". To redirect all
- commercial Spanish names (under COM.ES) one
- would use wildcard entries called "*.COM.ES.".
+ commercial Spanish names (under COM.ES),
+ use wildcard entries called "*.COM.ES.".
</para>
<para>
Note that the redirect zone supports all
<para>
Because redirect zones are not referenced
directly by name, they are not kept in the
- zone lookup table with normal master and slave
+ zone lookup table with normal primary and secondary
zones. Consequently, it is not currently possible
to use
<command>rndc reload
<replaceable>zonename</replaceable></command>
to reload a redirect zone. However, when using
<command>rndc reload</command> without specifying
- a zone name, redirect zones will be reloaded along
+ a zone name, redirect zones are reloaded along
with other zones.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- This is used to enforce the delegation-only
- status of infrastructure zones (e.g. COM,
+ This zone type is used to enforce the delegation-only
+ status of infrastructure zones (e.g., COM,
NET, ORG). Any answer that is received
without an explicit or implicit delegation
- in the authority section will be treated
+ in the authority section is treated
as NXDOMAIN. This does not apply to the
- zone apex. This should not be applied to
+ zone apex, and should not be applied to
leaf zones.
</para>
<para>
</para>
</entry>
</row>
+ <row rowsep="0">
+ <entry colname="1">
+ <para>
+ <varname>in-view</varname>
+ </para>
+ </entry>
+ <entry colname="2">
+ <para>
+ When using multiple views, a primary or secondary zone
+ configured in one view can be referenced in a
+ subsequent view. This allows both views to serve the
+ same zone without the overhead of loading it more
+ than once. This is configured using a
+ <varname>zone</varname> statement, with an
+ <varname>in-view</varname> option specifying the
+ view in which the zone is defined.
+ A <varname>zone</varname> statement containing
+ <varname>in-view</varname> does not need to specify
+ a type, since that is part of the zone definition
+ in the other view.
+ </para>
+ <para>
+ See <xref linkend="multiple_views"/> for more information.
+ </para>
+ </entry>
+ </row>
</tbody>
</tgroup>
</informaltable>
</para>
<para>
The <literal>hesiod</literal> class is
- named for an information service from MIT's Project Athena. It
- is
+ named for an information service from MIT's Project Athena. It was
used to share information about various systems databases, such
- as users, groups, printers and so on. The keyword
+ as users, groups, printers, and so on. The keyword
<literal>HS</literal> is
a synonym for hesiod.
</para>
<term><command>update-policy</command></term>
<listitem>
<para>
- Specifies a "Simple Secure Update" policy. See
+ This specifies a "Simple Secure Update" policy. See
<xref linkend="dynamic_update_policies"/>.
</para>
</listitem>
<term><command>also-notify</command></term>
<listitem>
<para>
- Only meaningful if <command>notify</command>
+ This option is only meaningful if <command>notify</command>
is
- active for this zone. The set of machines that will
+ active for this zone. The set of machines that
receive a
<literal>DNS NOTIFY</literal> message
for this zone is made up of all the listed name servers
(other than
- the primary master) for the zone plus any IP addresses
+ the primary) for the zone, plus any IP addresses
specified
with <command>also-notify</command>. A port
may be specified
<para>
This option is used to restrict the character set and
syntax of
- certain domain names in master files and/or DNS responses
+ certain domain names in zone files and/or DNS responses
received from the
- network. The default varies according to zone type. For <command>master</command> zones the default is <command>fail</command>. For <command>slave</command>
- zones the default is <command>warn</command>.
+ network. The default varies according to zone type.
+ For primary zones the default is <command>fail</command>;
+ for secondary zones the default is <command>warn</command>.
It is not implemented for <command>hint</command> zones.
</para>
</listitem>
<term><command>database</command></term>
<listitem>
<para>
- Specify the type of database to be used for storing the
+ This specifies the type of database to be used to store the
zone data. The string following the <command>database</command> keyword
is interpreted as a list of whitespace-delimited words.
The first word
<para>
The default is <userinput>"rbt"</userinput>, BIND 9's
native in-memory
- red-black-tree database. This database does not take
+ red-black tree database. This database does not take
arguments.
</para>
<para>
<term><command>delegation-only</command></term>
<listitem>
<para>
- The flag only applies to forward, hint and stub
+ This flag only applies to forward, hint, and stub
zones. If set to <userinput>yes</userinput>,
- then the zone will also be treated as if it is
+ then the zone is treated as if it is
also a delegation-only type zone.
</para>
<para>
<term><command>file</command></term>
<listitem>
<para>
- Set the zone's filename. In <command>master</command>,
+ This sets the zone's filename. In <command>master</command>,
<command>hint</command>, and <command>redirect</command>
zones which do not have <command>masters</command>
defined, zone data is loaded from this file. In
<term><command>forward</command></term>
<listitem>
<para>
- Only meaningful if the zone has a forwarders
+ This option is only meaningful if the zone has a forwarders
list. The <command>only</command> value causes
the lookup to fail
- after trying the forwarders and getting no answer, while <command>first</command> would
- allow a normal lookup to be tried.
+ after trying the forwarders and getting no answer, while <command>first</command>
+ allows a normal lookup to be tried.
</para>
</listitem>
</varlistentry>
<term><command>forwarders</command></term>
<listitem>
<para>
- Used to override the list of global forwarders.
+ This is used to override the list of global forwarders.
If it is not specified in a zone of type <command>forward</command>,
no forwarding is done for the zone and the global options are
not used.
<term><command>ixfr-base</command></term>
<listitem>
<para>
-
Was used in <acronym>BIND</acronym> 8 to
+
This was used in <acronym>BIND</acronym> 8 to
specify the name
of the transaction log (journal) file for dynamic update
and IXFR.
<term><command>ixfr-tmp-file</command></term>
<listitem>
<para>
-
Was an undocumented option in <acronym>BIND</acronym> 8.
- Ignored in <acronym>BIND</acronym> 9.
+
This was an undocumented option in <acronym>BIND</acronym> 8.
+ I
t is ignored in <acronym>BIND</acronym> 9.
</para>
</listitem>
</varlistentry>
<term><command>journal</command></term>
<listitem>
<para>
- Allow the default journal's filename to be overridden.
+ This allows the default journal's filename to be overridden.
The default is the zone's filename with "<filename>.jnl</filename>" appended.
- This is applicable to <command>master</command> and <command>slave</command> zones.
+ This is applicable to primary (<command>master</command>)
+ and secondary (<command>slave</command>) zones.
</para>
</listitem>
</varlistentry>
<listitem>
<para>
In <acronym>BIND</acronym> 8, this option was
- intended for specifying
- a public zone key for verification of signatures in DNSSEC
- signed
- zones when they are loaded from disk. <acronym>BIND</acronym> 9 does not verify signatures
+ intended to specify
+ a public zone key for verification of signatures in DNSSEC-signed
+ zones when they were loaded from disk. <acronym>BIND</acronym> 9 does not verify signatures
on load and ignores the option.
</para>
</listitem>
<term><command>server-addresses</command></term>
<listitem>
<para>
- Only meaningful for static-stub zones.
+ This option is only meaningful for static-stub zones.
This is a list of IP addresses to which queries
should be sent in recursive resolution for the
zone.
- A non empty list for this option will internally
- configure the apex NS RR with associated glue A or
+ A non-empty list for this option internally
+ configures the apex NS RR with associated glue A or
AAAA RRs.
</para>
<para>
For example, if "example.com" is configured as a
static-stub zone with 192.0.2.1 and 2001:db8::1234
in a <command>server-addresses</command> option,
- the following RRs will be internally configured.
+ the following RRs are internally configured:
</para>
<programlisting>example.com. NS example.com.
example.com. A 192.0.2.1
example.com. AAAA 2001:db8::1234</programlisting>
<para>
- These records are internally used to resolve
+ These records are used internally to resolve
names under the static-stub zone.
For instance, if the server receives a query for
"www.example.com" with the RD bit on, the server
- will initiate recursive resolution and send
+ initiates recursive resolution and sends
queries to 192.0.2.1 and/or 2001:db8::1234.
</para>
</listitem>
<term><command>server-names</command></term>
<listitem>
<para>
- Only meaningful for static-stub zones.
- This is a list of domain names of nameservers that
+ This option is only meaningful for static-stub zones.
+ This is a list of domain names of name servers that
act as authoritative servers of the static-stub
zone.
- These names will be resolved to IP addresses when
+ These names are resolved to IP addresses when
<command>named</command> needs to send queries to
these servers.
- To make this supplemental resolution successful,
+ For this supplemental resolution to be successful,
these names must not be a subdomain of the origin
- name of static-stub zone.
+ name of the static-stub zone.
That is, when "example.net" is the origin of a
static-stub zone, "ns.example" and
"master.example.com" can be specified in the
<command>server-names</command> option, but
- "ns.example.net" cannot, and will be rejected by
+ "ns.example.net" cannot; it is rejected by
the configuration parser.
</para>
<para>
- A non empty list for this option will internally
- configure the apex NS RR with the specified names.
+ A non-empty list for this option internally
+ configures the apex NS RR with the specified names.
For example, if "example.com" is configured as a
static-stub zone with "ns1.example.net" and
"ns2.example.net"
in a <command>server-names</command> option,
- the following RRs will be internally configured.
+ the following RRs are internally configured:
</para>
+
<programlisting>example.com. NS ns1.example.net.
example.com. NS ns2.example.net.
</programlisting>
+
<para>
- These records are internally used to resolve
+ These records are used internally to resolve
names under the static-stub zone.
For instance, if the server receives a query for
"www.example.com" with the RD bit on, the server
- initiate recursive resolution,
- resolve "ns1.example.net" and/or
- "ns2.example.net" to IP addresses, and then send
- queries to (one or more of) these addresses.
+ initiates recursive resolution,
+ resolves "ns1.example.net" and/or
+ "ns2.example.net" to IP addresses, and then sends
+ queries to one or more of these addresses.
</para>
</listitem>
</varlistentry>
<term><command>max-retry-time</command></term>
<listitem>
<para>
- See the description in <xref linkend="tuning"/>.
+ See the descriptions in <xref linkend="tuning"/>.
</para>
</listitem>
</varlistentry>
See the description of
<command>ixfr-from-differences</command> in <xref linkend="boolean_options"/>.
(Note that the <command>ixfr-from-differences</command>
- <userinput>master</userinput> and
- <userinput>slave</userinput> choices are not
+ choices of <userinput>master</userinput> and
+ <userinput>slave</userinput> are not
available at the zone level.)
</para>
</listitem>
<listitem>
<para>
If <literal>yes</literal>, this enables
- "bump in the wire" signing of a zone, where a
+ "bump in the wire" signing of a zone, where an
unsigned zone is transferred in or loaded from
disk and a signed version of the zone is served,
- with possibly, a different serial number. This
+ with, possibly, a different serial number. This
behavior is disabled by default.
</para>
</listitem>
</section>
<section xml:id="dynamic_update_policies"><info><title>Dynamic Update Policies</title></info>
- <para><acronym>BIND</acronym> 9 supports two alternative
+ <para><acronym>BIND</acronym> 9 supports two
methods of granting clients the right to perform
dynamic updates to a zone, configured by the
<command>allow-update</command> and
- <command>update-policy</command> option, respectively.
+ <command>update-policy</command> options.
</para>
<para>
The <command>allow-update</command> clause is a simple
</para>
<para>
The <command>update-policy</command> clause
- allows more fine-grained control over what updates are
+ allows more fine-grained control over which updates are
allowed. It specifies a set of rules, in which each rule
either grants or denies permission for one or more
names in the zone to be updated by one or more
identities. Identity is determined by the key that
- signed the update request using either TSIG or SIG(0).
+ signed the update request, using either TSIG or SIG(0).
In most cases, <command>update-policy</command> rules
only apply to key-based identities. There is no way
to specify update permissions based on client source
</para>
<para>
<command>update-policy</command> rules are only meaningful
- for zones of type <command>master</command>, and are
+ for primary zones (type <command>master</command>), and are
not allowed in any other zone type.
It is a configuration error to specify both
<command>allow-update</command> and
is "local-ddns", and the key algorithm is HMAC-SHA256.
These values are configurable with the
<command>session-keyfile</command>,
- <command>session-keyname</command> and
+ <command>session-keyname</command>, and
<command>session-keyalg</command> options, respectively.
A client running on the local system, if run with appropriate
permissions, may read the session key from the key file and
use it to sign update requests. The zone's update
- policy will be set to allow that key to change any record
+ policy is set to allow that key to change any record
within the zone. Assuming the key name is "local-ddns",
this policy is equivalent to:
</para>
</programlisting>
<para>
- ...with the additional restriction that only clients
- connecting from the local system will be permitted to send
+ with the additional restriction that only clients
+ connecting from the local system are permitted to send
updates.
</para>
<para>
Note that only one session key is generated by
<command>named</command>; all zones configured to use
- <command>update-policy local</command> will accept the same key.
+ <command>update-policy local</command> accept the same key.
</para>
<para>
The command <command>nsupdate -l</command> implements this
</para>
<para>
The <command>identity</command> field must be set to
- a fully-qualified domain name. In most cases, this
- represensts the name of the TSIG or SIG(0) key that must be
+ a fully qualified domain name. In most cases, this
+ represents the name of the TSIG or SIG(0) key that must be
used to sign the update request. If the specified name is a
wildcard, it is subject to DNS wildcard expansion, and the
rule may apply to multiple identities. When a TKEY exchange
has been used to create a shared secret, the identity of
- the key used to authenticate the TKEY exchange will be
+ the key used to authenticate the TKEY exchange is
used as the identity of the shared secret. Some rule types
use identities matching the client's Kerberos principal
(e.g, <userinput>"host/machine@REALM"</userinput>) or
</para>
<para>
The <replaceable>name</replaceable> field also specifies
- a fully-qualified domain name. This often
+ a fully qualified domain name. This often
represents the name of the record to be updated.
Interpretation of this field is dependent on rule type.
</para>
<para>
If no <command>types</command> are explicitly specified,
- then a rule matches all types except RRSIG, NS, SOA, NSEC
+ then a rule matches all types except RRSIG, NS, SOA, NSEC,
and NSEC3. Types may be specified by name, including
- "ANY" (ANY matches all types except NSEC and NSEC3,
- which can never be updated). Note that when an attempt
+ "ANY"; ANY matches all types except NSEC and NSEC3,
+ which can never be updated. Note that when an attempt
is made to delete all records associated with a name,
the rules are checked for each existing record type.
</para>
The <replaceable>ruletype</replaceable> field has 16
values:
<varname>name</varname>, <varname>subdomain</varname>,
- <varname>wildcard</varname>, <varname>self</varname>,
- <varname>selfsub</varname>, <varname>selfwild</varname>,
- <varname>krb5-self</varname>, <varname>ms-self</varname>,
- <varname>krb5-selfsub</varname>, <varname>ms-selfsub</varname>,
- <varname>krb5-subdomain</varname>,
- <varname>ms-subdomain</varname>,
- <varname>tcp-self</varname>, <varname>6to4-self</varname>,
- <varname>zonesub</varname>, and <varname>external</varname>.
+ <varname>zonesub</varname>, <varname>wildcard</varname>,
+ <varname>self</varname>, <varname>selfsub</varname>,
+ <varname>selfwild</varname>, <varname>ms-self</varname>,
+ <varname>ms-selfsub</varname>, <varname>ms-subdomain</varname>,
+ <varname>krb5-self</varname>, <varname>krb5-selfsub</varname>,
+ <varname>krb5-subdomain</varname>, <varname>tcp-self</varname>,
+ <varname>6to4-self</varname>, and <varname>external</varname>.
</para>
<informaltable>
<tgroup cols="2" colsep="0" rowsep="0" tgroupstyle="4Level-table">
</para>
</entry> <entry colname="2">
<para>
- Exact-match semantics. This rule matches
+ With exact-match semantics, this rule matches
when the name being updated is identical
to the contents of the
<replaceable>name</replaceable> field.
name as the record to be updated. In this case,
the <replaceable>identity</replaceable> field
can be specified as <constant>*</constant>
- (an asterisk).
+ (asterisk).
</para>
</entry>
</row>
</para>
</entry> <entry colname="2">
<para>
- This rule is similar to <varname>self</varname>
+ This rule is similar to <varname>self</varname>,
except that subdomains of <varname>self</varname>
can also be updated.
</para>
</para>
</entry> <entry colname="2">
<para>
- This rule is similar to <varname>self</varname>
+ This rule is similar to <varname>self</varname>,
except that only subdomains of
<varname>self</varname> can be updated.
</para>
</entry> <entry colname="2">
<para>
When a client sends an UPDATE using a Windows
- machine principal (for example, 'machine$@REALM'),
+ machine principal (for example, "machine$@REALM"),
this rule allows records with the absolute name
- of 'machine.REALM' to be updated.
+ of "machine.REALM" to be updated.
</para>
<para>
The realm to be matched is specified in the
</para>
</entry> <entry colname="2">
<para>
- This is similar to <command>ms-self</command>
+ This is similar to <command>ms-self</command>,
except it also allows updates to any subdomain of
the name specified in the Windows machine
principal, not just to the name itself.
</entry> <entry colname="2">
<para>
When a client sends an UPDATE using a Windows
- machine principal (for example, 'machine$@REALM'),
+ machine principal (for example, "machine$@REALM"),
this rule allows any machine in the specified
realm to update any record in the zone or in a
specified subdomain of the zone.
<para>
The <replaceable>name</replaceable> field
specifies the subdomain that may be updated.
- If set to "." (or any other name at or above
- the zone apex), any name in the zone can be
+ If set to "." or any other name at or above
+ the zone apex, any name in the zone can be
updated.
</para>
<para>
for the zone "example.com" includes
<userinput>grant EXAMPLE.COM ms-subdomain hosts.example.com. A AAAA</userinput>,
any machine with a valid principal in
- the realm <userinput>EXAMPLE.COM</userinput> will
- be able to update address records at or below
+ the realm <userinput>EXAMPLE.COM</userinput> is
+ able to update address records at or below
"hosts.example.com".
</para>
</entry>
<para>
When a client sends an UPDATE using a
Kerberos machine principal (for example,
- 'host/machine@REALM'), this rule allows
- records with the absolute name of 'machine'
- to be updated provided it has been authenticated
+ "host/machine@REALM"), this rule allows
+ records with the absolute name of "machine"
+ to be updated, provided it has been authenticated
by REALM. This is similar but not identical
- to <command>ms-self</command> due to the
- 'machine' part of the Kerberos principal
- being an absolute name instead of a unqualified
+ to <command>ms-self</command>, due to the
+ "machine" part of the Kerberos principal
+ being an absolute name instead of an unqualified
name.
</para>
<para>
</para>
</entry> <entry colname="2">
<para>
- This is similar to <command>krb5-self</command>
+ This is similar to <command>krb5-self</command>,
except it also allows updates to any subdomain of
- the name specified in the 'machine' part of the
+ the name specified in the "machine" part of the
Kerberos principal, not just to the name itself.
</para>
</entry>
This rule is identical to
<command>ms-subdomain</command>, except that it works
with Kerberos machine principals (i.e.,
- 'host/machine@REALM') rather than Windows machine
+ "host/machine@REALM") rather than Windows machine
principals.
</para>
</entry>
client's IP address into the
<literal>in-addr.arpa</literal> and
<literal>ip6.arpa</literal>
- namespaces match the name to be updated.
+ namespaces matches the name to be updated.
The <command>identity</command> field must match
that name. The <command>name</command> field
should be set to ".".
field, the format of which is
"<constant>local:</constant><replaceable>path</replaceable>",
where <replaceable>path</replaceable> is the location
- of a UNIX-domain socket. (Currently, "local" is the
+ of a Unix-domain socket. (Currently, "local" is the
only supported mechanism.)
</para>
<para>
Requests to the external daemon are sent over the
- UNIX-domain socket as datagrams with the following
+ Unix-domain socket as datagrams with the following
format:
</para>
<programlisting>
</informaltable>
</section>
- <section xml:id="multiple_views"><info><title>Multiple views</title></info>
+ <section xml:id="multiple_views"><info><title>Multiple Views</title></info>
<para>
When multiple views are in use, a zone may be
referenced by more than one of them. Often, the views
- will contain different zones with the same name, allowing
+ contain different zones with the same name, allowing
different clients to receive different answers for the same
queries. At times, however, it is desirable for multiple
views to contain identical zones. The
<command>in-view</command> zone option provides an efficient
- way to do this: it allows a view to reference a zone that
+ way to do this; it allows a view to reference a zone that
was defined in a previously configured view. Example:
</para>
<programlisting>
<para>
A <command>zone</command> statement which uses the
<command>in-view</command> option may not use any other
- options with the exception of <command>forward</command>
+ , with the exception of <command>forward</command>
and <command>forwarders</command>. (These options control
- the behavior of the containing view, rather than changing
+ the behavior of the containing view, rather than change
the zone object itself.)
</para>
<para>
- Zone level acls (e.g. allow-query, allow-transfer) and
- other configuration details of the zone are all set
- in the view the referenced zone is defined in. Care
- need to be taken to ensure that acls are wide enough
+ Zone-level ACLs (e.g., allow-query, allow-transfer), and
+ other configuration details of the zone, are all set
+ in the view the referenced zone is defined in. Be
+ careful to ensure that ACLs are wide enough
for all views referencing the zone.
</para>
<para>
<para>
This section, largely borrowed from RFC 1034, describes the
- concept of a Resource Record (RR) and explains when each is used.
+ concept of a Resource Record (RR) and explains when each type is used.
Since the publication of RFC 1034, several new RRs have been
identified
and implemented in the DNS. These are also included.
separate RRs. The order of RRs in a set is not significant and
need not be preserved by name servers, resolvers, or other
parts of the DNS. However, sorting of multiple RRs is
- permitted for optimization purposes, for example, to specify
+ permitted for optimization purposes: for example, to specify
that a particular nearby server be tried first. See <xref linkend="the_sortlist_statement"/> and <xref linkend="rrset_ordering"/>.
</para>
<entry colname="2">
<para>
An encoded 16-bit value that identifies
- a protocol family or instance of a protocol.
+ a protocol family or an instance of a protocol.
</para>
</entry>
</row>
<entry colname="2">
<para>
The resource data. The format of the
- data is type (and sometimes class) specific.
+ data is type- and sometimes class-specific.
</para>
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
+ <para>
+ For a complete list of <emphasis>types</emphasis> of valid RRs,
+ including those that have been obsoleted,
+ please refer to https://en.wikipedia.org/wiki/List_of_DNS_record_types.
+ </para>
+
<para>
- The following are <emphasis>types</emphasis> of valid RRs:
+ The following <emphasis>classes</emphasis> of resource records
+ are currently valid in the DNS:
</para>
- <informaltable colsep="0" rowsep="0">
- <tgroup cols="2" colsep="0" rowsep="0" tgroupstyle="4Level-table">
+ <informaltable colsep="0" rowsep="0"><tgroup cols="2" colsep="0" rowsep="0" tgroupstyle="4Level-table">
<colspec colname="1" colnum="1" colsep="0" colwidth="0.875in"/>
<colspec colname="2" colnum="2" colsep="0" colwidth="3.625in"/>
<tbody>
+
<row rowsep="0">
<entry colname="1">
<para>
- A
+ IN
</para>
</entry>
<entry colname="2">
<para>
- A host address. In the IN class, this is a
- 32-bit IP address. Described in RFC 1035.
+ The Internet.
</para>
</entry>
</row>
+
<row rowsep="0">
<entry colname="1">
<para>
- AAAA
+ CH
</para>
</entry>
<entry colname="2">
<para>
- IPv6 address. Described in RFC 1886.
+ Chaosnet, a LAN protocol created at MIT in the
+ mid-1970s.
+ It was rarely used for its historical purpose, but was reused for
+ BIND's
+ built-in server information zones, e.g.,
+ <literal>version.bind</literal>.
</para>
</entry>
</row>
+
<row rowsep="0">
<entry colname="1">
<para>
- A6
+ HS
</para>
</entry>
<entry colname="2">
<para>
- IPv6 address. This can be a partial
- address (a suffix) and an indirection to the name
- where the rest of the
- address (the prefix) can be found. Experimental.
- Described in RFC 2874.
+ Hesiod, an information service
+ developed by MIT's Project Athena. It was used to share
+ information
+ about various systems databases, such as users,
+ groups, printers,
+ etc.
</para>
</entry>
</row>
+
+ </tbody>
+ </tgroup>
+ </informaltable>
+
+ <para>
+ The owner name is often implicit, rather than forming an
+ integral
+ part of the RR. For example, many name servers internally form
+ tree
+ or hash structures for the name space, and chain RRs off nodes.
+ The remaining RR parts are the fixed header (type, class, TTL),
+ which is consistent for all RRs, and a variable part (RDATA)
+ that
+ fits the needs of the resource being described.
+ </para>
+ <para>
+ The TTL field is a time limit on how long an
+ RR can be kept in a cache. This limit does not apply to
+ authoritative
+ data in zones; that also times out, but follows the refreshing
+ policies
+ for the zone. The TTL is assigned by the administrator for the
+ zone where the data originates. While short TTLs can be used to
+ minimize caching, and a zero TTL prohibits caching, the
+ realities
+ of Internet performance suggest that these times should be on
+ the
+ order of days for the typical host. If a change can be
+ anticipated,
+ the TTL can be reduced prior to the change to minimize
+ inconsistency, and then increased back to its former value
+ following
+ the change.
+ </para>
+ <para>
+ The data in the RDATA section of RRs is carried as a combination
+ of binary strings and domain names. The domain names are
+ frequently
+ used as "pointers" to other data in the DNS.
+ </para>
+ </section>
+ <section xml:id="rr_text"><info><title>Textual Expression of RRs</title></info>
+
+ <para>
+ RRs are represented in binary form in the packets of the DNS
+ protocol, and are usually represented in highly encoded form
+ when
+ stored in a name server or resolver. In the examples provided
+ in
+ RFC 1034, a style similar to that used in zone files was
+ employed
+ in order to show the contents of RRs. In this format, most RRs
+ are shown on a single line, although continuation lines are
+ possible
+ using parentheses.
+ </para>
+ <para>
+ The start of the line gives the owner of the RR. If a line
+ begins with a blank, then the owner is assumed to be the same as
+ that of the previous RR. Blank lines are often included for
+ readability.
+ </para>
+ <para>
+ Following the owner are list the TTL, type, and class of the
+ RR. Class and type use the mnemonics defined above, and TTL is
+ an integer before the type field. To avoid ambiguity
+ in
+ parsing, type and class mnemonics are disjoint, TTLs are
+ integers,
+ and the type mnemonic is always last. The IN class and TTL
+ values
+ are often omitted from examples in the interest of clarity.
+ </para>
+ <para>
+ The resource data or RDATA section of the RR is given using
+ knowledge of the typical representation for the data.
+ </para>
+ <para>
+ For example, the RRs carried in a message might be shown as:
+ </para>
+ <informaltable colsep="0" rowsep="0"><tgroup cols="3" colsep="0" rowsep="0" tgroupstyle="4Level-table">
+ <colspec colname="1" colnum="1" colsep="0" colwidth="1.381in"/>
+ <colspec colname="2" colnum="2" colsep="0" colwidth="1.020in"/>
+ <colspec colname="3" colnum="3" colsep="0" colwidth="2.099in"/>
+ <tbody>
<row rowsep="0">
<entry colname="1">
<para>
- AFSDB
+ <literal>ISI.EDU.</literal>
</para>
</entry>
<entry colname="2">
<para>
- Location of AFS database servers.
- Experimental. Described in RFC 1183.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- AMTRELAY
+ <literal>MX</literal>
</para>
</entry>
- <entry colname="2">
+ <entry colname="3">
<para>
- Automatic Multicast Tunneling Relay
- discovery record.
- Work in progress draft-ietf-mboned-driad-amt-discovery.
+ <literal>10 VENERA.ISI.EDU.</literal>
</para>
</entry>
</row>
<row rowsep="0">
<entry colname="1">
+ <para/>
+ </entry>
+ <entry colname="2">
<para>
- APL
+ <literal>MX</literal>
</para>
</entry>
- <entry colname="2">
+ <entry colname="3">
<para>
- Address prefix list. Experimental.
- Described in RFC 3123.
+ <literal>10 VAXA.ISI.EDU</literal>
</para>
</entry>
</row>
<row rowsep="0">
<entry colname="1">
<para>
- ATMA
+ <literal>VENERA.ISI.EDU</literal>
</para>
</entry>
<entry colname="2">
<para>
- ATM Address.
+ <literal>A</literal>
+ </para>
+ </entry>
+ <entry colname="3">
+ <para>
+ <literal>128.9.0.32</literal>
</para>
</entry>
</row>
<row rowsep="0">
<entry colname="1">
+ <para/>
+ </entry>
+ <entry colname="2">
<para>
- AVC
+ <literal>A</literal>
</para>
</entry>
- <entry colname="2">
+ <entry colname="3">
<para>
- Application Visibility and Control record.
+ <literal>10.1.0.52</literal>
</para>
</entry>
</row>
<row rowsep="0">
<entry colname="1">
<para>
- CAA
+ <literal>VAXA.ISI.EDU</literal>
</para>
</entry>
<entry colname="2">
<para>
- Identifies which Certificate Authorities can issue
- certificates for this domain and what rules they
- need to follow when doing so. Defined in RFC 6844.
+ <literal>A</literal>
+ </para>
+ </entry>
+ <entry colname="3">
+ <para>
+ <literal>10.2.0.27</literal>
</para>
</entry>
</row>
<row rowsep="0">
<entry colname="1">
+ <para/>
+ </entry>
+ <entry colname="2">
<para>
- CDNSKEY
+ <literal>A</literal>
</para>
</entry>
- <entry colname="2">
+ <entry colname="3">
<para>
- Identifies which DNSKEY records should be published
- as DS records in the parent zone.
+ <literal>128.9.0.33</literal>
</para>
</entry>
</row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <para>
+ The MX RRs have an RDATA section which consists of a 16-bit
+ number followed by a domain name. The address RRs use a
+ standard
+ IP address format to contain a 32-bit Internet address.
+ </para>
+ <para>
+ The above example shows six RRs, with two RRs at each of three
+ domain names.
+ </para>
+ <para>
+ Here is another possible example:
+ </para>
+ <informaltable colsep="0" rowsep="0"><tgroup cols="3" colsep="0" rowsep="0" tgroupstyle="4Level-table">
+ <colspec colname="1" colnum="1" colsep="0" colwidth="1.491in"/>
+ <colspec colname="2" colnum="2" colsep="0" colwidth="1.067in"/>
+ <colspec colname="3" colnum="3" colsep="0" colwidth="2.067in"/>
+ <tbody>
<row rowsep="0">
<entry colname="1">
<para>
- CDS
+ <literal>XX.LCS.MIT.EDU.</literal>
</para>
</entry>
<entry colname="2">
<para>
- Contains the set of DS records that should be published
- by the parent zone.
+ <literal>IN A</literal>
</para>
</entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
+ <entry colname="3">
<para>
- CERT
+ <literal>10.0.0.44</literal>
</para>
</entry>
+ </row>
+ <row rowsep="0">
+ <entry colname="1"/>
<entry colname="2">
<para>
- Holds a digital certificate.
- Described in RFC 2538.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- CNAME
- </para>
- </entry>
- <entry colname="2">
- <para>
- Identifies the canonical name of an alias.
- Described in RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- CSYNC
- </para>
- </entry>
- <entry colname="2">
- <para>
- Child-to-Parent Synchronization in DNS as described
- in RFC 7477.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- DHCID
- </para>
- </entry>
- <entry colname="2">
- <para>
- Is used for identifying which DHCP client is
- associated with this name. Described in RFC 4701.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- DLV
- </para>
- </entry>
- <entry colname="2">
- <para>
- A DNS Look-aside Validation record which contains
- the records that are used as trust anchors for
- zones in a DLV namespace. Described in RFC 4431.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- DNAME
- </para>
- </entry>
- <entry colname="2">
- <para>
- Replaces the domain name specified with
- another name to be looked up, effectively aliasing an
- entire
- subtree of the domain name space rather than a single
- record
- as in the case of the CNAME RR.
- Described in RFC 2672.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- DNSKEY
- </para>
- </entry>
- <entry colname="2">
- <para>
- Stores a public key associated with a signed
- DNS zone. Described in RFC 4034.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- DOA
- </para>
- </entry>
- <entry colname="2">
- <para>
- Implements the Digital Object Architecture over
- DNS. Experimental.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- DS
- </para>
- </entry>
- <entry colname="2">
- <para>
- Stores the hash of a public key associated with a
- signed DNS zone. Described in RFC 4034.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- EID
- </para>
- </entry>
- <entry colname="2">
- <para>
- End Point Identifier.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- EUI48
- </para>
- </entry>
- <entry colname="2">
- <para>
- A 48-bit EUI address. Described in RFC 7043.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- EUI64
- </para>
- </entry>
- <entry colname="2">
- <para>
- A 64-bit EUI address. Described in RFC 7043.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- GID
- </para>
- </entry>
- <entry colname="2">
- <para>
- Reserved.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- GPOS
- </para>
- </entry>
- <entry colname="2">
- <para>
- Specifies the global position. Superseded by LOC.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- HINFO
- </para>
- </entry>
- <entry colname="2">
- <para>
- Identifies the CPU and OS used by a host.
- Described in RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- HIP
- </para>
- </entry>
- <entry colname="2">
- <para>
- Host Identity Protocol Address.
- Described in RFC 5205.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- IPSECKEY
- </para>
- </entry>
- <entry colname="2">
- <para>
- Provides a method for storing IPsec keying material in
- DNS. Described in RFC 4025.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- ISDN
- </para>
- </entry>
- <entry colname="2">
- <para>
- Representation of ISDN addresses.
- Experimental. Described in RFC 1183.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- KEY
- </para>
- </entry>
- <entry colname="2">
- <para>
- Stores a public key associated with a
- DNS name. Used in original DNSSEC; replaced
- by DNSKEY in DNSSECbis, but still used with
- SIG(0). Described in RFCs 2535 and 2931.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- KX
- </para>
- </entry>
- <entry colname="2">
- <para>
- Identifies a key exchanger for this
- DNS name. Described in RFC 2230.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- L32
- </para>
- </entry>
- <entry colname="2">
- <para>
- Holds 32-bit Locator values for
- Identifier-Locator Network Protocol. Described
- in RFC 6742.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- L64
- </para>
- </entry>
- <entry colname="2">
- <para>
- Holds 64-bit Locator values for
- Identifier-Locator Network Protocol. Described
- in RFC 6742.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- LOC
- </para>
- </entry>
- <entry colname="2">
- <para>
- For storing GPS info. Described in RFC 1876.
- Experimental.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- LP
- </para>
- </entry>
- <entry colname="2">
- <para>
- Identifier-Locator Network Protocol.
- Described in RFC 6742.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MB
- </para>
- </entry>
- <entry colname="2">
- <para>
- Mail Box. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MD
- </para>
- </entry>
- <entry colname="2">
- <para>
- Mail Destination. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MF
- </para>
- </entry>
- <entry colname="2">
- <para>
- Mail Forwarder. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MG
- </para>
- </entry>
- <entry colname="2">
- <para>
- Mail Group. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MINFO
- </para>
- </entry>
- <entry colname="2">
- <para>
- Mail Information.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MR
- </para>
- </entry>
- <entry colname="2">
- <para>
- Mail Rename. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- MX
- </para>
- </entry>
- <entry colname="2">
- <para>
- Identifies a mail exchange for the domain with
- a 16-bit preference value (lower is better)
- followed by the host name of the mail exchange.
- Described in RFC 974, RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NAPTR
- </para>
- </entry>
- <entry colname="2">
- <para>
- Name authority pointer. Described in RFC 2915.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NID
- </para>
- </entry>
- <entry colname="2">
- <para>
- Holds values for Node Identifiers in
- Identifier-Locator Network Protocol. Described
- in RFC 6742.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NINFO
- </para>
- </entry>
- <entry colname="2">
- <para>
- Contains zone status information.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NIMLOC
- </para>
- </entry>
- <entry colname="2">
- <para>
- Nimrod Locator.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NSAP
- </para>
- </entry>
- <entry colname="2">
- <para>
- A network service access point.
- Described in RFC 1706.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NSAP-PTR
- </para>
- </entry>
- <entry colname="2">
- <para>
- Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NS
- </para>
- </entry>
- <entry colname="2">
- <para>
- The authoritative name server for the
- domain. Described in RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NSEC
- </para>
- </entry>
- <entry colname="2">
- <para>
- Used in DNSSECbis to securely indicate that
- RRs with an owner name in a certain name interval do
- not exist in
- a zone and indicate what RR types are present for an
- existing name.
- Described in RFC 4034.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NSEC3
- </para>
- </entry>
- <entry colname="2">
- <para>
- Used in DNSSECbis to securely indicate that
- RRs with an owner name in a certain name
- interval do not exist in a zone and indicate
- what RR types are present for an existing
- name. NSEC3 differs from NSEC in that it
- prevents zone enumeration but is more
- computationally expensive on both the server
- and the client than NSEC. Described in RFC
- 5155.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NSEC3PARAM
- </para>
- </entry>
- <entry colname="2">
- <para>
- Used in DNSSECbis to tell the authoritative
- server which NSEC3 chains are available to use.
- Described in RFC 5155.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NULL
- </para>
- </entry>
- <entry colname="2">
- <para>
- This is an opaque container.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- NXT
- </para>
- </entry>
- <entry colname="2">
- <para>
- Used in DNSSEC to securely indicate that
- RRs with an owner name in a certain name interval do
- not exist in
- a zone and indicate what RR types are present for an
- existing name.
- Used in original DNSSEC; replaced by NSEC in
- DNSSECbis.
- Described in RFC 2535.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- OPENPGPKEY
- </para>
- </entry>
- <entry colname="2">
- <para>
- Used to hold an OPENPGPKEY.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- PTR
- </para>
- </entry>
- <entry colname="2">
- <para>
- A pointer to another part of the domain
- name space. Described in RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- PX
- </para>
- </entry>
- <entry colname="2">
- <para>
- Provides mappings between RFC 822 and X.400
- addresses. Described in RFC 2163.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- RKEY
- </para>
- </entry>
- <entry colname="2">
- <para>
- Resource key.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- RP
- </para>
- </entry>
- <entry colname="2">
- <para>
- Information on persons responsible
- for the domain. Experimental. Described in RFC 1183.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- RRSIG
- </para>
- </entry>
- <entry colname="2">
- <para>
- Contains DNSSECbis signature data. Described
- in RFC 4034.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- RT
- </para>
- </entry>
- <entry colname="2">
- <para>
- Route-through binding for hosts that
- do not have their own direct wide area network
- addresses.
- Experimental. Described in RFC 1183.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SIG
- </para>
- </entry>
- <entry colname="2">
- <para>
- Contains DNSSEC signature data. Used in
- original DNSSEC; replaced by RRSIG in
- DNSSECbis, but still used for SIG(0).
- Described in RFCs 2535 and 2931.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SINK
- </para>
- </entry>
- <entry colname="2">
- <para>
- The kitchen sink record.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SMIMEA
- </para>
- </entry>
- <entry colname="2">
- <para>
- The S/MIME Security Certificate Association.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SOA
- </para>
- </entry>
- <entry colname="2">
- <para>
- Identifies the start of a zone of authority.
- Described in RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SPF
- </para>
- </entry>
- <entry colname="2">
- <para>
- Contains the Sender Policy Framework information
- for a given email domain. Described in RFC 4408.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SRV
- </para>
- </entry>
- <entry colname="2">
- <para>
- Information about well known network
- services (replaces WKS). Described in RFC 2782.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- SSHFP
- </para>
- </entry>
- <entry colname="2">
- <para>
- Provides a way to securely publish a secure shell key's
- fingerprint. Described in RFC 4255.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- TA
- </para>
- </entry>
- <entry colname="2">
- <para>
- Trust Anchor. Experimental.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- TALINK
- </para>
- </entry>
- <entry colname="2">
- <para>
- Trust Anchor Link. Experimental.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- TLSA
- </para>
- </entry>
- <entry colname="2">
- <para>
- Transport Layer Security Certificate Association.
- Described in RFC 6698.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- TXT
- </para>
- </entry>
- <entry colname="2">
- <para>
- Text records. Described in RFC 1035.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- UID
- </para>
- </entry>
- <entry colname="2">
- <para>
- Reserved.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- UINFO
- </para>
- </entry>
- <entry colname="2">
- <para>
- Reserved.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- UNSPEC
- </para>
- </entry>
- <entry colname="2">
- <para>
- Reserved. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- URI
- </para>
- </entry>
- <entry colname="2">
- <para>
- Holds a URI. Described in RFC 7553.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- WKS
- </para>
- </entry>
- <entry colname="2">
- <para>
- Information about which well known
- network services, such as SMTP, that a domain
- supports. Historical.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- X25
- </para>
- </entry>
- <entry colname="2">
- <para>
- Representation of X.25 network addresses.
- Experimental. Described in RFC 1183.
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- ZONEMD
- </para>
- </entry>
- <entry colname="2">
- <para>
- Zone Message Digest.
- Work in progress draft-wessels-dns-zone-digest.
- </para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- <para>
- The following <emphasis>classes</emphasis> of resource records
- are currently valid in the DNS:
- </para>
- <informaltable colsep="0" rowsep="0"><tgroup cols="2" colsep="0" rowsep="0" tgroupstyle="4Level-table">
- <colspec colname="1" colnum="1" colsep="0" colwidth="0.875in"/>
- <colspec colname="2" colnum="2" colsep="0" colwidth="3.625in"/>
- <tbody>
-
- <row rowsep="0">
- <entry colname="1">
- <para>
- IN
- </para>
- </entry>
- <entry colname="2">
- <para>
- The Internet.
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry colname="1">
- <para>
- CH
- </para>
- </entry>
- <entry colname="2">
- <para>
- Chaosnet, a LAN protocol created at MIT in the
- mid-1970s.
- Rarely used for its historical purpose, but reused for
- BIND's
- built-in server information zones, e.g.,
- <literal>version.bind</literal>.
- </para>
- </entry>
- </row>
-
- <row rowsep="0">
- <entry colname="1">
- <para>
- HS
- </para>
- </entry>
- <entry colname="2">
- <para>
- Hesiod, an information service
- developed by MIT's Project Athena. It is used to share
- information
- about various systems databases, such as users,
- groups, printers
- and so on.
- </para>
- </entry>
- </row>
-
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>
- The owner name is often implicit, rather than forming an
- integral
- part of the RR. For example, many name servers internally form
- tree
- or hash structures for the name space, and chain RRs off nodes.
- The remaining RR parts are the fixed header (type, class, TTL)
- which is consistent for all RRs, and a variable part (RDATA)
- that
- fits the needs of the resource being described.
- </para>
- <para>
- The meaning of the TTL field is a time limit on how long an
- RR can be kept in a cache. This limit does not apply to
- authoritative
- data in zones; it is also timed out, but by the refreshing
- policies
- for the zone. The TTL is assigned by the administrator for the
- zone where the data originates. While short TTLs can be used to
- minimize caching, and a zero TTL prohibits caching, the
- realities
- of Internet performance suggest that these times should be on
- the
- order of days for the typical host. If a change can be
- anticipated,
- the TTL can be reduced prior to the change to minimize
- inconsistency
- during the change, and then increased back to its former value
- following
- the change.
- </para>
- <para>
- The data in the RDATA section of RRs is carried as a combination
- of binary strings and domain names. The domain names are
- frequently
- used as "pointers" to other data in the DNS.
- </para>
- </section>
- <section xml:id="rr_text"><info><title>Textual expression of RRs</title></info>
-
- <para>
- RRs are represented in binary form in the packets of the DNS
- protocol, and are usually represented in highly encoded form
- when
- stored in a name server or resolver. In the examples provided
- in
- RFC 1034, a style similar to that used in master files was
- employed
- in order to show the contents of RRs. In this format, most RRs
- are shown on a single line, although continuation lines are
- possible
- using parentheses.
- </para>
- <para>
- The start of the line gives the owner of the RR. If a line
- begins with a blank, then the owner is assumed to be the same as
- that of the previous RR. Blank lines are often included for
- readability.
- </para>
- <para>
- Following the owner, we list the TTL, type, and class of the
- RR. Class and type use the mnemonics defined above, and TTL is
- an integer before the type field. In order to avoid ambiguity
- in
- parsing, type and class mnemonics are disjoint, TTLs are
- integers,
- and the type mnemonic is always last. The IN class and TTL
- values
- are often omitted from examples in the interests of clarity.
- </para>
- <para>
- The resource data or RDATA section of the RR are given using
- knowledge of the typical representation for the data.
- </para>
- <para>
- For example, we might show the RRs carried in a message as:
- </para>
- <informaltable colsep="0" rowsep="0"><tgroup cols="3" colsep="0" rowsep="0" tgroupstyle="4Level-table">
- <colspec colname="1" colnum="1" colsep="0" colwidth="1.381in"/>
- <colspec colname="2" colnum="2" colsep="0" colwidth="1.020in"/>
- <colspec colname="3" colnum="3" colsep="0" colwidth="2.099in"/>
- <tbody>
- <row rowsep="0">
- <entry colname="1">
- <para>
- <literal>ISI.EDU.</literal>
- </para>
- </entry>
- <entry colname="2">
- <para>
- <literal>MX</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>10 VENERA.ISI.EDU.</literal>
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para/>
- </entry>
- <entry colname="2">
- <para>
- <literal>MX</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>10 VAXA.ISI.EDU</literal>
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- <literal>VENERA.ISI.EDU</literal>
- </para>
- </entry>
- <entry colname="2">
- <para>
- <literal>A</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>128.9.0.32</literal>
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para/>
- </entry>
- <entry colname="2">
- <para>
- <literal>A</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>10.1.0.52</literal>
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para>
- <literal>VAXA.ISI.EDU</literal>
- </para>
- </entry>
- <entry colname="2">
- <para>
- <literal>A</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>10.2.0.27</literal>
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1">
- <para/>
- </entry>
- <entry colname="2">
- <para>
- <literal>A</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>128.9.0.33</literal>
- </para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- <para>
- The MX RRs have an RDATA section which consists of a 16-bit
- number followed by a domain name. The address RRs use a
- standard
- IP address format to contain a 32-bit internet address.
- </para>
- <para>
- The above example shows six RRs, with two RRs at each of three
- domain names.
- </para>
- <para>
- Similarly we might see:
- </para>
- <informaltable colsep="0" rowsep="0"><tgroup cols="3" colsep="0" rowsep="0" tgroupstyle="4Level-table">
- <colspec colname="1" colnum="1" colsep="0" colwidth="1.491in"/>
- <colspec colname="2" colnum="2" colsep="0" colwidth="1.067in"/>
- <colspec colname="3" colnum="3" colsep="0" colwidth="2.067in"/>
- <tbody>
- <row rowsep="0">
- <entry colname="1">
- <para>
- <literal>XX.LCS.MIT.EDU.</literal>
- </para>
- </entry>
- <entry colname="2">
- <para>
- <literal>IN A</literal>
- </para>
- </entry>
- <entry colname="3">
- <para>
- <literal>10.0.0.44</literal>
- </para>
- </entry>
- </row>
- <row rowsep="0">
- <entry colname="1"/>
- <entry colname="2">
- <para>
- <literal>CH A</literal>
+ <literal>CH A</literal>
</para>
</entry>
<entry colname="3">
series of resource records, each of which contains a particular
piece of information about a given domain name (which is usually,
but not always, a host). The simplest way to think of a RR is as
- a typed pair of data, a domain name matched with a relevant datum,
- and stored with some additional type information to help systems
+ a typed pair of data, a domain name matched with a relevant datum
+ and stored with some additional type information, to help systems
determine when the RR is relevant.
</para>
controls the order in which email delivery is attempted, with the
lowest number first. If two priorities are the same, a server is
chosen randomly. If no servers at a given priority are responding,
- the mail transport agent will fall back to the next largest
+ the mail transport agent falls back to the next largest
priority.
- Priority numbers do not have any absolute meaning — they are
+ Priority numbers do not have any absolute meaning; they are
relevant
only respective to other MX records for that domain name. The
domain
- name given is the machine to which the mail will be delivered.
+ name given is the machine to which the mail is delivered.
It <emphasis>must</emphasis> have an associated address record
- (A or AAAA) — CNAME is not sufficient.
+ (A or AAAA); CNAME is not sufficient.
</para>
<para>
For a given domain, if there is both a CNAME record and an
- MX record, the MX record is in error, and will be ignored.
+ MX record, the MX record is in error, and is ignored.
Instead,
- the mail will be delivered to the server specified in the MX
+ the mail is delivered to the server specified in the MX
record
pointed to by the CNAME.
For example:
</tbody>
</tgroup>
</informaltable><para>
- Mail delivery will be attempted to <literal>mail.example.com</literal> and
+ Mail delivery is attempted to <literal>mail.example.com</literal> and
<literal>mail2.example.com</literal> (in
- any order), and if neither of those succeed, delivery to <literal>mail.backup.org</literal> will
- be attempted.
+ any order); if neither of those succeeds, delivery to <literal>mail.backup.org</literal>
+ is attempted.
</para>
</section>
<section xml:id="Setting_TTLs"><info><title>Setting TTLs</title></info>
<para>
- The time-to-live of the RR field is a 32-bit integer represented
+ The time-to- (TTL) of the RR field is a 32-bit integer represented
in units of seconds, and is primarily used by resolvers when they
- cache RRs. The TTL describes how long a RR can be cached before it
- should be discarded. The following three types of TTL are
+ cache RRs. The TTL describes how long an RR can be cached before it
+ should be discarded. The following three types of TTLs are
currently
used in a zone file.
</para>
<entry colname="2">
<para>
The last field in the SOA is the negative
- caching TTL. This controls how long other servers will
+ caching TTL. This controls how long other servers
cache no-such-domain
- (NXDOMAIN) responses from you.
+ (NXDOMAIN) responses from this server.
</para>
<para>
The maximum time for
<entry colname="2">
<para>
Each RR can have a TTL as the second
- field in the RR, which will control how long other
+ field in the RR, which controls how long other
servers can cache it.
</para>
</entry>
</informaltable>
<para>
All of these TTLs default to units of seconds, though units
- can be explicitly specified, for example, <literal>1h30m</literal>.
+ can be explicitly specified: for example, <literal>1h30m</literal>.
</para>
</section>
<section xml:id="ipv4_reverse"><info><title>Inverse Mapping in IPv4</title></info>
</informaltable>
<note>
<para>
- The <command>$ORIGIN</command> lines in the examples
- are for providing context to the examples only — they do not
+ The <command>$ORIGIN</command> line in this example
+ is only to provide context; it does not
necessarily
- appear in the actual usage. They are only used here to indicate
+ appear in the actual usage. It is only used here to indicate
that the example is relative to the listed origin.
</para>
</note>
<section xml:id="zone_directives"><info><title>Other Zone File Directives</title></info>
<para>
- The Master File Format was initially defined in RFC 1035 and
- has subsequently been extended. While the Master File Format
+ The DNS "master file" format was initially defined in RFC 1035 and
+ has subsequently been extended. While the format
itself
- is class independent all records in a Master File must be of the
+ is class-independent, all records in a zone file must be of the
same
class.
</para>
<para>
- Master File Directives include <command>$ORIGIN</command>, <command>$INCLUDE</command>,
+ Master file directives include <command>$ORIGIN</command>, <command>$INCLUDE</command>,
and <command>$TTL.</command>
</para>
<section xml:id="atsign"><info><title>The <command>@</command> (at-sign)</title></info>
When used in the label (or name) field, the asperand or
at-sign (@) symbol represents the current origin.
At the start of the zone file, it is the
- <<varname>zone_name</varname>> (followed by
- trailing dot).
+ <<varname>zone_name</varname>>, followed by a
+ trailing dot (.).
</para>
</section>
<section xml:id="origin_directive"><info><title>The <command>$ORIGIN</command> Directive</title></info>
<optional><replaceable>comment</replaceable></optional>
</para>
<para><command>$ORIGIN</command>
- sets the domain name that will be appended to any
- unqualified records. When a zone is first read in there
+ sets the domain name that is appended to any
+ unqualified records. When a zone is first read, there
is an implicit <command>$ORIGIN</command>
- <<varname>zone_name</varname>><command>.</command>
- (followed by trailing dot).
+ <<varname>zone_name</varname>><command>.</command>;
+ note the trailing dot.
The current <command>$ORIGIN</command> is appended to
the domain specified in the <command>$ORIGIN</command>
argument if it is not absolute.
<optional> <replaceable>comment</replaceable> </optional>
</para>
<para>
- Read and process the file <filename>filename</filename> as
- if it were included into the file at this point. If <command>origin</command> is
- specified the file is processed with <command>$ORIGIN</command> set
- to that value, otherwise the current <command>$ORIGIN</command> is
+ This reads and processes the file <filename>filename</filename> as
+ if it were included in the file at this point. If <command>origin</command> is
+ specified, the file is processed with <command>$ORIGIN</command> set
+ to that value; otherwise, the current <command>$ORIGIN</command> is
used.
</para>
<para>
<replaceable>comment</replaceable> </optional>
</para>
<para>
- Set the default Time To Live (TTL) for subsequent records
+ This sets the default Time-To-Live (TTL) for subsequent records
with undefined TTLs. Valid TTLs are of the range 0-2147483647
seconds.
</para>
</para>
</section>
</section>
- <section xml:id="generate_directive"><info><title><acronym>BIND</acronym> Master File Extension: the <command>$GENERATE</command> Directive</title></info>
+ <section xml:id="generate_directive"><info><title><acronym>BIND</acronym> Primary File Extension: the <command>$GENERATE</command> Directive</title></info>
<para>
Syntax: <command>$GENERATE</command>
differ from each other by an
iterator. <command>$GENERATE</command> can be used to
easily generate the sets of records required to support
- sub /24 reverse delegations described in RFC 2317:
+ sub-/24 reverse delegations described in RFC 2317:
Classless IN-ADDR.ARPA delegation.
</para>
</programlisting>
<para>
- Generate a set of A and MX records. Note the MX's right hand
- side is a quoted string. The quotes will be stripped when the
- right hand side is processed.
+ Both generate a set of A and MX records. Note the MX's right-hand
+ side is a quoted string. The quotes are stripped when the
+ right-hand side is processed.
</para>
<programlisting>
<para>
This can be one of two forms: start-stop
or start-stop/step. If the first form is used, then step
- is set to 1. start, stop and step must be positive
- integers between 0 and (2^31)-1. start must not be
- larger than stop.
+ is set to 1. "start", "stop", and "step" must be positive
+ integers between 0 and (2^31)-1. "start" must not be
+ larger than "stop".
</para>
</entry>
</row>
symbols within the <command>lhs</command> string
are replaced by the iterator value.
- To get a $ in the output, you need to escape the
+ To get a $ in the output, escape the
<command>$</command> using a backslash
<command>\</command>,
- e.g. <command>\$</command>. The
+ e.g., <command>\$</command>. The
<command>$</command> may optionally be followed
by modifiers which change the offset from the
- iterator, field width and base.
+ iterator, field width, and base.
Modifiers are introduced by a
<command>{</command> (left brace) immediately following the
- <command>$</command> as
+ <command>$</command>, as in
<command>${offset[,width[,base]]}</command>.
For example, <command>${-20,3,d}</command>
- subtracts 20 from the current value, prints the
+ subtracts 20 from the current value and prints the
result as a decimal in a zero-padded field of
width 3.
(<command>d</command>), octal
(<command>o</command>), hexadecimal
(<command>x</command> or <command>X</command>
- for uppercase) and nibble
- (<command>n</command> or <command>N</command>\
+ for uppercase), and nibble
+ (<command>n</command> or <command>N</command>
for uppercase). The default modifier is
<command>${0,0,d}</command>. If the
<command>lhs</command> is not absolute, the
to the name.
</para>
<para>
- In nibble mode the value will be treated as
- if it was a reversed hexadecimal string
+ In nibble mode, the value is treated as
+ if it were a reversed hexadecimal string,
with each hexadecimal digit as a separate
label. The width field includes the label
separator.
</entry>
<entry colname="2">
<para>
- Specifies the time-to-live of the generated records. If
- not specified this will be inherited using the
+ This specifies the time-to-live of the generated records. If
+ not specified, this is inherited using the
normal TTL inheritance rules.
</para>
<para><command>class</command>
</entry>
<entry colname="2">
<para>
- Specifies the class of the generated records.
+ This specifies the class of the generated records.
This must match the zone class if it is
specified.
</para>
</entry>
<entry colname="2">
<para>
- Any valid type.
+ This can be any valid type.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- <command>rhs</command>, optionally, quoted string.
+ <command>rhs</command> is an optionally quoted string.
</para>
</entry>
</row>
<section xml:id="zonefile_format"><info><title>Additional File Formats</title></info>
<para>
- In addition to the standard textual format, BIND 9
+ In addition to the standard text format, BIND 9
supports the ability to read or dump to zone files in
other formats.
</para>
<para>
An even faster alternative is the <constant>map</constant>
format, which is an image of a <acronym>BIND</acronym> 9
- in-memory zone database; it is capable of being loaded
+ in-memory zone database; it can be loaded
directly into memory via the <command>mmap()</command>
- function; the zone can begin serving queries almost
+ function and the zone can begin serving queries almost
immediately.
</para>
<para>
<constant>raw</constant> or <constant>map</constant>
format is expected to be generated from a textual zone
file by the <command>named-compilezone</command> command.
- For a secondary server or for a dynamic zone, it is automatically
- generated (if this format is specified by the
- <command>masterfile-format</command> option) when
+ For a secondary server or for a dynamic zone, the zone file is automatically
+ generated when
<command>named</command> dumps the zone contents after
- zone transfer or when applying prior updates.
+ zone transfer or when applying prior updates, if one of these formats is specified by the
+ <command>masterfile-format</command> option.
</para>
<para>
If a zone file in a binary format needs manual modification,
it first must be converted to a textual form by the
- <command>named-compilezone</command> command. All
- necessary modification should go to the text file, which
- should then be converted to the binary form by the
+ <command>named-compilezone</command> command. Make any
+ necessary modifications to the text file, and
+ then convert it to the binary form via the
<command>named-compilezone</command> command again.
</para>
<para>
Note that <command>map</command> format is extremely
architecture-specific. A <constant>map</constant>
file <emphasis>cannot</emphasis> be used on a system
- with different pointer size, endianness or data alignment
+ with different pointer size, endianness, or data alignment
than the system on which it was generated, and should in
general be used only inside a single system.
While <constant>raw</constant> format uses
</section>
</section>
- <section xml:id="statistics"><info><title>BIND9 Statistics</title></info>
+ <section xml:id="statistics"><info><title>BIND 9 Statistics</title></info>
<para>
<acronym>BIND</acronym> 9 maintains lots of statistics
information and provides several interfaces for users to
- get access to the statistics.
+ access those statistics.
The available statistics include all statistics counters
- that were available in <acronym>BIND</acronym> 8 and
- are meaningful in <acronym>BIND</acronym> 9,
+ that are meaningful in <acronym>BIND</acronym> 9,
and other information that is considered useful.
</para>
<para>
The statistics information is categorized into the following
- sections.
+ sections:
</para>
<informaltable frame="all">
<entry colname="2">
<para>
The number of outgoing queries for each RR
- type sent from the internal resolver.
- Maintained per view.
+ type sent from the internal resolver,
+ maintained per view.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Statistics counters about incoming request processing.
+ Statistics counters for incoming request processing.
</para>
</entry>
</row>
<entry colname="2">
<para>
Statistics counters regarding zone maintenance
- operations such as zone transfers.
+ operations, such as zone transfers.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Statistics counters about name resolution
- performed in the internal resolver.
- Maintained per view.
+ Statistics counters for name resolutions
+ performed in the internal resolver,
+ maintained per view.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- The number of RRsets per RR type and nonexistent
- names stored in the cache database.
- If the exclamation mark (!) is printed for a RR
- type, it means that particular type of RRset is
- known to be nonexistent (this is also known as
- "NXRRSET"). If a hash mark (#) is present then
- the RRset is marked for garbage collection.
- Maintained per view.
+ Statistics counters related to cache contents,
+ maintained per view.
+ </para>
+ <para>
+ The "NXDOMAIN" counter is the number of names
+ that have been cached as nonexistent.
+ Counters named for RR types indicate the
+ number of active RRsets for each type in the cache
+ database.
+ </para>
+ <para>
+ If an RR type name is preceded by an exclamation
+ point (!), it represents the number of records in the
+ cache which indicate that the type does not exist
+ for a particular name; this is also known as "NXRRSET".
+ If an RR type name is preceded by a hash mark (#), it
+ represents the number of RRsets for this type that are
+ present in the cache but whose TTLs have expired; these
+ RRsets may only be used if stale answers are enabled.
+ If an RR type name is preceded by a tilde (~), it
+ represents the number of RRsets for this type that are
+ present in the cache database but are marked for garbage
+ collection; these RRsets cannot be used.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Statistics counters about network related events.
+ Statistics counters for network-related events.
</para>
</entry>
</row>
<para>
A subset of Name Server Statistics is collected and shown
- per zone for which the server has the authority when
+ per zone for which the server has the authority, when
<command>zone-statistics</command> is set to
- <userinput>full</userinput> (or <userinput>yes</userinput>
+ <userinput>full</userinput> (or <userinput>yes</userinput>),
for backward compatibility. See the description of
<command>zone-statistics</command> in <xref linkend="options"/>
for further details.
<para>
There are currently two user interfaces to get access to the
statistics.
- One is in the plain text format dumped to the file specified
- by the <command>statistics-file</command> configuration option.
- The other is remotely accessible via a statistics channel
+ One is in plain-text format, dumped to the file specified
+ by the <command>statistics-file</command> configuration option;
+ the other is remotely accessible via a statistics channel
when the <command>statistics-channels</command> statement
is specified in the configuration file
(see <xref linkend="statschannels"/>.)
</para>
<para>
The number in parentheses is a standard
- Unix-style timestamp, measured as seconds since January 1, 1970.
+ Unix-style timestamp, measured in seconds since January 1, 1970.
Following
that line is a set of statistics information, which is categorized
<para>
Each section consists of lines, each containing the statistics
- counter value followed by its textual description.
- See below for available counters.
+ counter value followed by its textual description;
+ see below for available counters.
For brevity, counters that have a value of 0 are not shown
in the statistics file.
</para>
<section xml:id="statistics_counters"><info><title>Statistics Counters</title></info>
<para>
- The following tables summarize statistics counters that
+ The following tables summarize the statistics counters that
<acronym>BIND</acronym> 9 provides.
For each row of the tables, the leftmost column is the
- abbreviated symbol name of that counter.
- These symbols are shown in the statistics information
+ abbreviated symbol name of that counter;
+ these symbols are shown in the statistics information
accessed via an HTTP statistics channel.
The rightmost column gives the description of the counter,
- which is also shown in the statistics file
- (but, in this document, possibly with slight modification
- for better readability).
+ which is also shown in the statistics file,
+ but, in this document, may be slightly modified
+ for better readability.
Additional notes may also be provided in this column.
When a middle column exists between these two columns,
it gives the corresponding counter name of the
</entry>
<entry colname="2">
<para>
- <emphasis>BIND8 Symbol</emphasis>
+ <emphasis>BIND 8 Symbol</emphasis>
</para>
</entry>
<entry colname="3">
</entry>
<entry colname="3">
<para>
- IPv4 requests received.
- Note: this also counts non query requests.
+ This indicates the number of IPv4 requests received.
+ Note: this also counts non-query requests.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv6 requests received.
- Note: this also counts non query requests.
+ This indicates the number of IPv6 requests received.
+ Note: this also counts non-query requests.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Requests with EDNS(0) received.
+ This indicates the number of requests received with EDNS(0).
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Requests with unsupported EDNS version received.
+ This indicates the number of requests received with an unsupported EDNS version.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Requests with TSIG received.
+ This indicates the number of requests received with TSIG.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Requests with SIG(0) received.
+ This indicates the number of requests received with SIG(0).
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Requests with invalid (TSIG or SIG(0)) signature.
+ This indicates the number of requests received with an invalid (TSIG or SIG(0)) signature.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- TCP requests received.
+ This indicates the number of TCP requests received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Authoritative (non recursive) queries rejected.
+ This indicates the number of rejected authoritative (non-recursive) queries.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Recursive queries rejected.
+ This indicates the number of rejected recursive queries.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Zone transfer requests rejected.
+ This indicates the number of rejected zone transfer requests.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Dynamic update requests rejected.
+ This indicates the number of rejected dynamic update requests.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Responses sent.
+ This indicates the number of responses sent.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Truncated responses sent.
+ This indicates the number of truncated responses sent.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Responses with EDNS(0) sent.
+ This indicates the number of responses sent with EDNS(0).
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Responses with TSIG sent.
+ This indicates the number of responses sent with TSIG.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Responses with SIG(0) sent.
+ This indicates the number of responses sent with SIG(0).
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries resulted in a successful answer.
- This means the query which returns a NOERROR response
+ This indicates the number of queries that resulted in a successful answer,
+ meaning queries which return a NOERROR response
with at least one answer RR.
This corresponds to the
<command>success</command> counter
</entry>
<entry colname="3">
<para>
- Queries resulted in authoritative answer.
+ This indicates the number of queries that resulted in an authoritative answer.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries resulted in non authoritative answer.
+ This indicates the number of queries that resulted in a non-authoritative answer.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries resulted in referral answer.
+ This indicates the number of queries that resulted in a referral answer.
This corresponds to the
<command>referral</command> counter
of previous versions of
</entry>
<entry colname="3">
<para>
- Queries resulted in NOERROR responses with no data.
+ This indicates the number of queries that resulted in NOERROR responses with no data.
This corresponds to the
<command>nxrrset</command> counter
of previous versions of
</entry>
<entry colname="3">
<para>
- Queries resulted in SERVFAIL.
+ This indicates the number of queries that resulted in SERVFAIL.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries resulted in FORMERR.
+ This indicates the number of queries that resulted in FORMERR.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries resulted in NXDOMAIN.
+ This indicates the number of queries that resulted in NXDOMAIN.
This corresponds to the
<command>nxdomain</command> counter
of previous versions of
</entry>
<entry colname="3">
<para>
- Queries which caused the server
+ This indicates the number of queries that caused the server
to perform recursion in order to find the final answer.
This corresponds to the
<command>recursion</command> counter
</entry>
<entry colname="3">
<para>
- Queries which the server attempted to
- recurse but discovered an existing query with the same
- IP address, port, query ID, name, type and class
+ This indicates the number of queries which the server attempted to
+ recurse but for which it discovered an existing query with the same
+ IP address, port, query ID, name, type, and class
already being processed.
This corresponds to the
<command>duplicate</command> counter
</entry>
<entry colname="3">
<para>
- Recursive queries for which the server
+ This indicates the number of recursive queries for which the server
discovered an excessive number of existing
- recursive queries for the same name, type and
- class and were subsequently dropped.
+ recursive queries for the same name, type, and
+ class, and which were subsequently dropped.
This is the number of dropped queries due to
the reason explained with the
<command>clients-per-query</command>
</entry>
<entry colname="3">
<para>
- Other query failures.
+ This indicates the number of query failures.
This corresponds to the
<command>failure</command> counter
of previous versions of
<acronym>BIND</acronym> 9.
Note: this counter is provided mainly for
- backward compatibility with the previous versions.
- Normally a more fine-grained counters such as
+ backward compatibility with the previous versions;
+ normally, more fine-grained counters such as
<command>AuthQryRej</command> and
<command>RecQryRej</command>
that would also fall into this counter are provided,
- and so this counter would not be of much
+ so this counter is not of much
interest in practice.
</para>
</entry>
</entry>
<entry colname="3">
<para>
- Queries resulted in NXDOMAIN that were redirected.
+ This indicates the number of queries that resulted in NXDOMAIN that were redirected.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries resulted in NXDOMAIN that were redirected
+ This indicates the number of queries that resulted in NXDOMAIN that were redirected
and resulted in a successful remote lookup.
</para>
</entry>
</entry>
<entry colname="3">
<para>
- Requested zone transfers completed.
+ This indicates the number of requested and completed zone transfers.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Update requests forwarded.
+ This indicates the number of forwarded update requests.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Update responses forwarded.
+ This indicates the number of forwarded update responses.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Dynamic update forward failed.
+ This indicates the number of forwarded dynamic updates that failed.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Dynamic updates completed.
+ This indicates the number of completed dynamic updates.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Dynamic updates failed.
+ This indicates the number of failed dynamic updates.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Dynamic updates rejected due to prerequisite failure.
+ This indicates the number of dynamic updates rejected due to a prerequisite failure.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Responses dropped by rate limits.
+ This indicates the number of responses dropped due to rate limits.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Responses truncated by rate limits.
+ This indicates the number of responses truncated by rate limits.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Response policy zone rewrites.
+ This indicates the number of response policy zone rewrites.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv4 notifies sent.
+ This indicates the number of IPv4 notifies sent.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv6 notifies sent.
+ This indicates the number of IPv6 notifies sent.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv4 notifies received.
+ This indicates the number of IPv4 notifies received.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv6 notifies received.
+ This indicates the number of IPv6 notifies received.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Incoming notifies rejected.
+ This indicates the number of incoming notifies rejected.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv4 SOA queries sent.
+ This indicates the number of IPv4 SOA queries sent.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv6 SOA queries sent.
+ This indicates the number of IPv6 SOA queries sent.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv4 AXFR requested.
+ This indicates the number of requested IPv4 AXFRs.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv6 AXFR requested.
+ This indicates the number of requested IPv6 AXFRs.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv4 IXFR requested.
+ This indicates the number of requested IPv4 IXFRs.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- IPv6 IXFR requested.
+ This indicates the number of requested IPv6 IXFRs.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Zone transfer requests succeeded.
+ This indicates the number of successful zone transfer requests.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Zone transfer requests failed.
+ This indicates the number of failed zone transfer requests.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- <emphasis>BIND8 Symbol</emphasis>
+ <emphasis>BIND 8 Symbol</emphasis>
</para>
</entry>
<entry colname="3">
</entry>
<entry colname="3">
<para>
- IPv4 queries sent.
+ This indicates the number of IPv4 queries sent.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv6 queries sent.
+ This indicates the number of IPv6 queries sent.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv4 responses received.
+ This indicates the number of IPv4 responses received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv6 responses received.
+ This indicates the number of IPv6 responses received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- NXDOMAIN received.
+ This indicates the number of NXDOMAINs received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- SERVFAIL received.
+ This indicates the number of SERVFAILs received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- FORMERR received.
+ This indicates the number of FORMERRs received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Other errors received.
+ This indicates the number of other errors received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- EDNS(0) query failures.
+ This indicates the number of EDNS(0) query failures.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Mismatch responses received.
- The DNS ID, response's source address,
+ This indicates the number of mismatched responses received,
+ meaning the DNS ID, response's source address,
and/or the response's source port does not
match what was expected.
(The port must be 53 or as defined by
</entry>
<entry colname="3">
<para>
- Truncated responses received.
+ This indicates the number of truncated responses received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Lame delegations received.
+ This indicates the number of lame delegations received.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Query retries performed.
+ This indicates the number of query retries performed.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Queries aborted due to quota control.
+ This indicates the number of queries aborted due to quota control.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Failures in opening query sockets.
+ This indicates the number of failures in opening query sockets.
One common reason for such failures is a
- failure of opening a new socket due to a
- limitation on file descriptors.
+ due to a limitation on file descriptors.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Query timeouts.
+ This indicates the number of query timeouts.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv4 NS address fetches invoked.
+ This indicates the number of IPv4 NS address fetches invoked.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv6 NS address fetches invoked.
+ This indicates the number of IPv6 NS address fetches invoked.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv4 NS address fetch failed.
+ This indicates the number of failed IPv4 NS address fetches.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- IPv6 NS address fetch failed.
+ This indicates the number of failed IPv6 NS address fetches.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- DNSSEC validation attempted.
+ This indicates the number of attempted DNSSEC validations.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- DNSSEC validation succeeded.
+ This indicates the number of successful DNSSEC validations.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- DNSSEC validation on negative information succeeded.
+ This indicates the number of successful DNSSEC validations on negative information.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- DNSSEC validation failed.
+ This indicates the number of failed DNSSEC validations.
</para>
</entry>
</row>
</entry>
<entry colname="3">
<para>
- Frequency table on round trip times (RTTs) of
- queries.
+ This provides a frequency table on query round-trip times (RTTs).
Each <command>nn</command> specifies the corresponding
frequency.
In the sequence of
number of queries whose RTTs are between
<command>nn_(i-1)</command> (inclusive) and
<command>nn_i</command> (exclusive) milliseconds.
- For the sake of convenience we define
+ For the sake of convenience, we define
<command>nn_0</command> to be 0.
The last entry should be represented as
<command>nn_m+</command>, which means the
- number of queries whose RTTs are equal to or over
+ number of queries whose RTTs are equal to or greater than
<command>nn_m</command> milliseconds.
</para>
</entry>
<para>
Socket I/O statistics counters are defined per socket
- types, which are
+ type, which are
<command>UDP4</command> (UDP/IPv4),
<command>UDP6</command> (UDP/IPv6),
<command>TCP4</command> (TCP/IPv4),
<command>Unix</command> (Unix Domain), and
<command>FDwatch</command> (sockets opened outside the
socket module).
- In the following table <command><TYPE></command>
+ In the following table, <command><TYPE></command>
represents a socket type.
Not all counters are available for all socket types;
exceptions are noted in the description field.
</entry>
<entry colname="2">
<para>
- Sockets opened successfully.
- This counter is not applicable to the
+ This indicates the number of sockets opened successfully.
+ This counter does not apply to the
<command>FDwatch</command> type.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- Failures of opening sockets.
- This counter is not applicable to the
+ This indicates the number of failures to open sockets.
+ This counter does not apply to the
<command>FDwatch</command> type.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- Sockets closed.
+ This indicates the number of closed sockets.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Failures of binding sockets.
+ This indicates the number of failures to bind sockets.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Failures of connecting sockets.
+ This indicates the number of failures to connect sockets.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Connections established successfully.
+ This indicates the number of connections established successfully.
</para>
</entry>
</row>
</entry>
<entry colname="2">
<para>
- Failures of accepting incoming connection requests.
- This counter is not applicable to the
+ This indicates the number of failures to accept incoming connection requests.
+ This counter does not apply to the
<command>UDP</command> and
<command>FDwatch</command> types.
</para>
</entry>
<entry colname="2">
<para>
- Incoming connections successfully accepted.
- This counter is not applicable to the
+ This indicates the number of incoming connections successfully accepted.
+ This counter does not apply to the
<command>UDP</command> and
<command>FDwatch</command> types.
</para>
</entry>
<entry colname="2">
<para>
- Errors in socket send operations.
+ This indicates the number of errors in socket send operations.
This counter corresponds
- to <command>SErr</command> counter of
+ to the <command>SErr</command> counter of
<command>BIND</command> 8.
</para>
</entry>
</entry>
<entry colname="2">
<para>
- Errors in socket receive operations.
- This includes errors of send operations on a
- connected UDP socket notified by an ICMP error
+ This indicates the number of errors in socket receive operations,
+ including errors of send operations on a
+ connected UDP socket, notified by an ICMP error
message.
</para>
</entry>
<para>
Most statistics counters that were available
in <command>BIND</command> 8 are also supported in
- <command>BIND</command> 9 as shown in the above tables.
+ <command>BIND</command> 9, as shown in the above tables.
Here are notes about other counters that do not appear
in these tables.
</para>
<term><command>RFwdR,SFwdR</command></term>
<listitem>
<para>
- These counters are not supported
+ These counters are not supported,
because <command>BIND</command> 9 does not adopt
the notion of <emphasis>forwarding</emphasis>
as <command>BIND</command> 8 did.
<term><command>ROpts</command></term>
<listitem>
<para>
- This counter is not supported
+ This counter is not supported,
because <command>BIND</command> 9 does not care
- about IP options in the first place.
+ about IP options.
</para>
</listitem>
</varlistentry>
<para>
Access Control Lists (ACLs) are address match lists that
- you can set up and nickname for future use in
+ can be set up and nicknamed for future use in
<command>allow-notify</command>, <command>allow-query</command>,
<command>allow-query-on</command>, <command>allow-recursion</command>,
<command>blackhole</command>, <command>allow-transfer</command>,
<command>match-clients</command>, etc.
</para>
<para>
- Using ACLs allows you to have finer control over who can access
- your name server, without cluttering up your config files with huge
+ ACLs give users finer control over who can access
+ the name server, without cluttering up configuration files with huge
lists of IP addresses.
</para>
<para>
It is a <emphasis>good idea</emphasis> to use ACLs, and to
- control access to your server. Limiting access to your server by
+ control access. Limiting access to the server by
outside parties can help prevent spoofing and denial of service
- (DoS) attacks against your server.
+ (DoS) attacks against the server.
</para>
<para>
ACLs match clients on the basis of up to three characteristics:
1) The client's IP address; 2) the TSIG or SIG(0) key that was
used to sign the request, if any; and 3) an address prefix
- encoded in an EDNS Client Subnet option, if any.
+ encoded in an EDNS Client-Subnet option, if any.
</para>
<para>
Here is an example of ACLs based on client addresses:
</para>
<programlisting>
-// Set up an ACL named "bogusnets" that will block
-// RFC1918 space and some reserved space, which is
+// Set up an ACL named "bogusnets" that blocks
+// RFC 1918 space and some reserved space, which is
// commonly used in spoofing attacks.
acl bogusnets {
0.0.0.0/8; 192.0.2.0/24; 224.0.0.0/3;
may include <option>key</option> elements, which specify the
name of a TSIG or SIG(0) key, or <option>ecs</option>
elements, which specify a network prefix but are only matched
- if that prefix matches an EDNS client subnet option included
+ if that prefix matches an EDNS client-subnet option included
in the request.
</para>
<para>
- The EDNS Client Subnet (ECS) option is used by a recursive
+ The EDNS Client-Subnet (ECS) option is used by a recursive
resolver to inform an authoritative name server of the network
address block from which the original query was received, enabling
authoritative servers to give different answers to the same
</para>
<note>
<simpara>
- (Note: The authoritative ECS implementation in
+ (Note: the authoritative ECS implementation in
<command>named</command> is based on an early version of the
specification, and is known to have incompatibilities with
other implementations. It is also inefficient, requiring
<command>geoip <optional>db <replaceable>database</replaceable></optional> <replaceable>field</replaceable> <replaceable>value</replaceable></command>
</para>
<para>
- The <replaceable>field</replaceable> indicates which field
+ The <replaceable>field</replaceable> parameter indicates which field
to search for a match. Available fields are "country",
"region", "city", "continent", "postal" (postal code),
"metro" (metro code), "area" (area code), "tz" (timezone),
contains spaces or other special characters. An "asnum"
search for autonomous system number can be specified using
the string "ASNNNN" or the integer NNNN.
- When "country" search is specified with a string is two
- characters long, then it must be a standard ISO-3166-1
- two-letter country code; otherwise it is interpreted as
- the full name of the country. Similarly, if this is a
- "region" search and the string is two characters long,
- then it treated as a standard two-letter state or province
- abbreviation; otherwise it treated as the full name of the
+ When "country" search is specified with a string that is two
+ characters long, it must be a standard ISO-3166-1
+ two-letter country code; otherwise, it is interpreted as
+ the full name of the country. Similarly, if
+ "region" is the search term and the string is two characters long,
+ it is treated as a standard two-letter state or province
+ abbreviation; otherwise, it is treated as the full name of the
state or province.
</para>
<para>
can be answered from either the "city" or "country" databases,
so for these search types, specifying a
<replaceable>database</replaceable>
- will force the query to be answered from that database and no
+ forces the query to be answered from that database and no
other. If <replaceable>database</replaceable> is not
- specified, then these queries will be answered from the "city",
- database if it is installed, or the "country" database if it
- is installed, in that order. Valid database names are
+ specified, these queries are first answered from the "city"
+ database if it is installed, and then from the "country" database if it
+ is installed. Valid database names are
"country", "city", "asnum", "isp", and "domain". (If using
the legacy GeoIP API, "netspeed" and "org" databases are also
available.)
</para>
<para>
- By default, if a DNS query includes an EDNS Client Subnet (ECS)
- option which encodes a non-zero address prefix, then GeoIP ACLs
- will be matched against that address prefix. Otherwise, they
- are matched against the source address of the query. To
+ By default, if a DNS query includes an EDNS Client-Subnet (ECS)
+ option which encodes a non-zero address prefix, then GeoIP ACL
+ elements are matched against that address prefix. Otherwise,
+ they are matched against the source address of the query. To
prevent GeoIP ACLs from matching against ECS options, set
the <command>geoip-use-ecs</command> to <literal>no</literal>.
</para>
</programlisting>
<para>
- ACLs use a "first-match" logic rather than "best-match":
+ ACLs use a "first-match" logic rather than "best-match";
if an address prefix matches an ACL element, then that ACL
is considered to have matched even if a later element would
have matched more specifically. For example, the ACL
- <command> { 10/8; !10.0.0.1; }</command> would actually
+ <command>{ 10/8; !10.0.0.1; }</command> would actually
match a query from 10.0.0.1, because the first element
- indicated that the query should be accepted, and the second
+ indicates that the query should be accepted, and the second
element is ignored.
</para>
<para>
When using "nested" ACLs (that is, ACLs included or referenced
- within other ACLs), a negative match of a nested ACL will
+ within other ACLs), a negative match of a nested ACL tells
the containing ACL to continue looking for matches. This
enables complex ACLs to be constructed, in which multiple
client characteristics can be checked at the same time. For
- example, to construct an ACL which allows queries only when
+ example, to construct an ACL which allows a query only when
it originates from a particular network <emphasis>and</emphasis>
only when it is signed with a particular key, use:
</para>
</programlisting>
<para>
Within the nested ACL, any address that is
- <emphasis>not</emphasis> in the 10/8 network prefix will
- be rejected, and this will terminate processing of the
+ <emphasis>not</emphasis> in the 10/8 network prefix is
+ rejected, which terminates processing of the
ACL. Any address that <emphasis>is</emphasis> in the 10/8
- network prefix will be accepted, but this causes a negative
+ network prefix is accepted, but this causes a negative
match of the nested ACL, so the containing ACL continues
- processing. The query will then be accepted if it is signed
+ processing. The query is accepted if it is signed
by the key "example", and rejected otherwise. The ACL, then,
- will only matches when <emphasis>both</emphasis> conditions
+ only matches when <emphasis>both</emphasis> conditions
are true.
</para>
</section>
<section xml:id="chroot_and_setuid"><info><title><command>Chroot</command> and <command>Setuid</command></title></info>
<para>
- On U
NIX servers, it is possible to run <acronym>BIND</acronym>
+ On U
nix servers, it is possible to run <acronym>BIND</acronym>
in a <emphasis>chrooted</emphasis> environment (using
the <command>chroot()</command> function) by specifying
the <option>-t</option> option for <command>named</command>.
This can help improve system security by placing
- <acronym>BIND</acronym> in a "sandbox", which will limit
+ <acronym>BIND</acronym> in a "sandbox," which limits
the damage done if a server is compromised.
</para>
<para>
- Another useful feature in the U
NIX version of <acronym>BIND</acronym> is the
- ability to run the daemon as an unprivileged user ( <option>-u</option> <replaceable>user</replaceable> ).
+ Another useful feature in the U
nix version of <acronym>BIND</acronym> is the
+ ability to run the daemon as an unprivileged user (<option>-u</option> <replaceable>user</replaceable>).
We suggest running as an unprivileged user when using the <command>chroot</command> feature.
</para>
<para>
<section xml:id="chroot"><info><title>The <command>chroot</command> Environment</title></info>
<para>
- In order for a <command>chroot</command> environment
+ For a <command>chroot</command> environment
to work properly in a particular directory (for example,
- <filename>/var/named</filename>), you will need to set
- up an environment that includes everything
+ <filename>/var/named</filename>), the
+ environment must include everything
<acronym>BIND</acronym> needs to run. From
<acronym>BIND</acronym>'s point of view,
<filename>/var/named</filename> is the root of the
- filesystem. You will need to adjust the values of
+ filesystem; the values of
options like <command>directory</command> and
- <command>pid-file</command> to account for this.
+ <command>pid-file</command> must be adjusted to account for this.
</para>
<para>
- Unlike with earlier versions of BIND, you typically will
- <emphasis>not</emphasis> need to compile <command>named</command>
- statically nor install shared libraries under the new root.
- However, depending on your operating system, you may need
- to set up things like
+ Unlike with earlier versions of BIND,
+ <command>named</command> does <emphasis>not</emphasis> typically need to be compiled
+ statically, nor do shared libraries need to be installed under the new root.
+ However, depending on the operating system, it may be necessary
+ to set up locations such as
<filename>/dev/zero</filename>,
<filename>/dev/random</filename>,
<filename>/dev/log</filename>, and
modification times) or the <command>chown</command>
utility (to
set the user id and/or group id) on files
-
to which you want <acronym>BIND</acronym>
- to write.
+
where <acronym>BIND</acronym>
+ should write.
</para>
<note><simpara>
If the <command>named</command> daemon is running as an
- unprivileged user, it will not be able to bind to new restricted
+ unprivileged user, it cannot bind to new restricted
ports if the server is reloaded.
</simpara></note>
</section>
or
network prefix in the <command>allow-update</command>
zone option.
- This method is insecure since the source address of the update UDP
+ This method is insecure, since the source address of the update UDP
packet
is easily forged. Also note that if the IP addresses allowed by the
<command>allow-update</command> option include the
- address of a slave
- server which performs forwarding of dynamic updates, the master can
+ address of a secondary
+ server which performs forwarding of dynamic updates, the primary can
be
- trivially attacked by sending the update to the slave, which will
- forward it to the master with its own source IP address causing the
- master to approve it without question.
+ trivially attacked by sending the update to the secondary, which
+ forwards it to the primary with its own source IP address - causing the
+ primary to approve it without question.
</para>
<para>
(TSIG). That is, the <command>allow-update</command>
option should
list only TSIG key names, not IP addresses or network
- prefixes. Alternatively, the new <command>update-policy</command>
+ prefixes. Alternatively, the <command>update-policy</command>
option can be used.
</para>
<para>
- Some sites choose to keep all dynamically-updated DNS data
+ Some sites choose to keep all dynamically updated DNS data
in a subdomain and delegate that subdomain to a separate zone. This
- way, the top-level zone containing critical data such as the IP
+ way, the top-level zone containing critical data, such as the IP
addresses
- of public web and mail servers need not allow dynamic update at
+ of public web and mail servers, need not allow dynamic update at
all.
</para>
<section xml:id="common_problems"><info><title>Common Problems</title></info>
- <section><info><title>It's not working; how can I figure out what's wrong?</title></info>
+ <section><info><title>It's Not Working; How Can I Figure Out What's Wrong?</title></info>
<para>
- The best solution to solving installation and
- configuration issues is to take preventative measures by setting
+ The best solution to installation and
+ configuration issues is to take preventive measures by setting
up logging files beforehand. The log files provide a
- source of hints and information that can be used to figure out
- what went wrong and how to fix the problem.
+ source of hints and information that can be used to identify
+ what went wrong and fix the problem.
</para>
</section>
<section><info><title>Incrementing and Changing the Serial Number</title></info>
<para>
- Zone serial numbers are just numbers — they aren't
- date related. A lot of people set them to a number that
+ Zone serial numbers are just numbers — they are not
+ date-related. However, many people set them to a number that
represents a date, usually of the form YYYYMMDDRR.
- Occasionally they will make a mistake and set them to a
- "date in the future" then try to correct them by setting
- them to the "current date". This causes problems because
+ Occasionally they make a mistake and set the serial number to a
+ date in the future, then try to correct it by setting
+ it to the current date. This causes problems because
serial numbers are used to indicate that a zone has been
- updated. If the serial number on the slave server is
- lower than the serial number on the master, the slave
- server will attempt to update its copy of the zone.
+ updated. If the serial number on the secondary server is
+ lower than the serial number on the primary, the secondary
+ server attempts to update its copy of the zone.
</para>
<para>
- Setting the serial number to a lower number on the master
- server than the slave server means that the slave will not perform
+ Setting the serial number to a lower number on the primary
+ server than the one on the secondary server means that the secondary will not perform
updates to its copy of the zone.
</para>
<para>
The solution to this is to add 2147483647 (2^31-1) to the
- number, reload the zone and make sure all slaves have updated to
- the new zone serial number, then reset the number to what you want
- it to be, and reload the zone again.
+ number, reload the zone and make sure all secondaries have updated to
+ the new zone serial number, then reset it to the desired number
+ and reload the zone again.
</para>
</section>
<section xml:id="more_help"><info><title>Where Can I Get Help?</title></info>
<para>
- The Internet Systems Consortium
- (<acronym>ISC</acronym>) offers a wide range
- of support and service agreements for <acronym>BIND</acronym> and <acronym>DHCP</acronym> servers. Four
- levels of premium support are available and each level includes
- support for all <acronym>ISC</acronym> programs,
- significant discounts on products
- and training, and a recognized priority on bug fixes and
- non-funded feature requests. In addition, <acronym>ISC</acronym> offers a standard
- support agreement package which includes services ranging from bug
- fix announcements to remote support. It also includes training in
- <acronym>BIND</acronym> and <acronym>DHCP</acronym>.
+ The BIND-users mailing list, at https://lists.isc.org/mailman/listinfo/bind-users,
+ is an excellent resource for peer user support. In addition, <acronym>ISC</acronym> maintains a
+ Knowledgebase of helpful articles at https://kb.isc.org.
</para>
<para>
- To discuss arrangements for support, contact
- <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="mailto:info@isc.org">info@isc.org</link> or visit the
- <acronym>ISC</acronym> web page at
- <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.isc.org/services/support/">http://www.isc.org/services/support/</link>
- to read more.
+ Internet Systems Consortium
+ (<acronym>ISC</acronym>) offers annual
+ support agreements for <acronym>BIND</acronym>9, ISC <acronym>DHCP</acronym>, and Kea DHCP.
+ All paid support contracts include advance security notifications; some levels include
+ service level agreements (SLAs), premium software features, and increased priority on bug fixes
+ and feature requests.
+ </para>
+
+ <para>
+ Please contact
+ <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="mailto:info@isc.org">info@isc.org</link> or visit
+ <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.isc.org/contact/">https://www.isc.org/contact/</link>
+ for more information.
</para>
</section>
</chapter>
<appendix xml:id="Bv9ARM.ch10"><info><title>A Brief History of the <acronym>DNS</acronym> and <acronym>BIND</acronym></title></info>
<para xml:id="historical_dns_information">
- Although the "official" beginning of the Domain Name
- System occurred in 1984 with the publication of RFC 920, the
+ Although the Domain Name
+ System "officially" began in 1984 with the publication of RFC 920, the
core of the new system was described in 1983 in RFCs 882 and
883. From 1984 to 1987, the ARPAnet (the precursor to today's
Internet) became a testbed of experimentation for developing the
operational network environment. New RFCs were written and
published in 1987 that modified the original documents to
incorporate improvements based on the working model. RFC 1034,
- "Domain Names-Concepts and Facilities", and RFC 1035, "Domain
- Names-Implementation and Specification" were published and
+ "Domain Names-Concepts and Facilities," and RFC 1035, "Domain
+ Names-Implementation and Specification," were published and
became the standards upon which all <acronym>DNS</acronym> implementations are
built.
</para>
<para>
- The first working domain name server, called "Jeeves", was
+ The first working domain name server, called "Jeeves," was
written in 1983-84 by Paul Mockapetris for operation on DEC
Tops-20
machines located at the University of Southern California's
Versions of <acronym>BIND</acronym> through
4.8.3 were maintained by the Computer
Systems Research Group (CSRG) at UC Berkeley. Douglas Terry, Mark
- Painter, David Riggle and Songnian Zhou made up the initial <acronym>BIND</acronym>
+ Painter, David Riggle
, and Songnian Zhou made up the initial <acronym>BIND</acronym>
project team. After that, additional work on the software package
was done by Ralph Campbell. Kevin Dunlap, a Digital Equipment
Corporation
<para>
<acronym>BIND</acronym> versions 4.9 and 4.9.1 were
released by Digital Equipment
- Corporation (now Compaq Computer Corporation). Paul Vixie, then
+ Corporation (which became Compaq Computer Corporation and eventually merged with Hewlett-Packard). Paul Vixie, then
a DEC employee, became <acronym>BIND</acronym>'s
primary caretaker. He was assisted
by Phil Almquist, Robert Elz, Alan Barrett, Paul Albitz, Bryan
<para>
<acronym>BIND</acronym> versions from 4.9.3 onward
have been developed and maintained
- by the Internet Systems Consortium and its predecessor,
- the Internet Software Consortium, with support being provided
+ by Internet Systems Consortium and its predecessor,
+ the Internet Software Consortium, with support provided
by ISC's sponsors.
</para>
<para>
<para>
<acronym>BIND</acronym> development work is made
possible today by the sponsorship
- of several corporations, and by the tireless work efforts of
+ of corporations who purchase professional support services from ISC
+ (https://www.isc.org/contact/) and/or donate to our mission, and by the tireless efforts of
numerous individuals.
</para>
</appendix>
<section xml:id="ipv6addresses"><info><title>IPv6 addresses (AAAA)</title></info>
<para>
- IPv6 addresses are 128-bit identifiers for interfaces and
- sets of interfaces which were introduced in the <acronym>DNS</acronym> to facilitate
+ IPv6 addresses are 128-bit identifiers, for interfaces and
+ sets of interfaces
, which were introduced in the <acronym>DNS</acronym> to facilitate
scalable Internet routing. There are three types of addresses: <emphasis>Unicast</emphasis>,
an identifier for a single interface;
<emphasis>Anycast</emphasis>,
an identifier for a set of interfaces; and <emphasis>Multicast</emphasis>,
an identifier for a set of interfaces. Here we describe the global
Unicast address scheme. For more information, see RFC 3587,
- "Global Unicast Address Format."
+ "IPv6 Global Unicast Address Format."
</para>
<para>
IPv6 unicast addresses consist of a
</para>
<para>
The global routing prefix is provided by the
- upstream provider or ISP, and (roughly) corresponds to the
+ upstream provider or ISP, and roughly corresponds to the
IPv4 <emphasis>network</emphasis> section
of the address range.
- The subnet identifier is for local subnetting, much the
- same as subnetting an
+ The subnet identifier is for local subnetting, much
+ like subnetting an
IPv4 /16 network into /24 subnets.
The interface identifier is the address of an individual
</para>
<para>
The subnetting capability of IPv6 is much more flexible than
- that of IPv4: subnetting can be carried out on bit boundaries,
+ that of IPv4; subnetting can be carried out on bit boundaries,
in much the same way as Classless InterDomain Routing
(CIDR), and the DNS PTR representation ("nibble" format)
makes setting up reverse zones easier.
</para>
<para>
- The Interface Identifier must be unique on the local link,
+ The interface identifier must be unique on the local link,
and is usually generated automatically by the IPv6
implementation, although it is usually possible to
override the default setting if necessary. A typical IPv6
address might look like:
- <command>2001:db8:201:9:a00:20ff:fe81:2b32</command>
+ <command>2001:db8:201:9:a00:20ff:fe81:2b32</command>.
</para>
<para>
IPv6 address specifications often contain long strings
of zeros, so the architects have included a shorthand for
specifying
- them. The double colon (`::') indicates the longest possible
+ them. The double colon ("::") indicates the longest possible
string
of zeros that can fit, and can be used only once in an address.
</para>
the Request for Comments (RFCs)
series of technical notes. The standards themselves are defined
by the Internet Engineering Task Force (IETF) and the Internet
- Engineering Steering Group (IESG). RFCs can be obtained online via FTP at:
+ Engineering Steering Group (IESG). RFCs can be obtained online at:
</para>
<para>
- <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ftp://www.isi.edu/in-notes/">
- ftp://www.isi.edu/in-notes/RFC<replaceable>xxxx</replaceable>.txt
+ <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://datatracker.ietf.org/doc/">
+ https://datatracker.ietf.org/doc/
</link>
</para>
- <para>
- (where <replaceable>xxxx</replaceable> is
- the number of the RFC). RFCs are also available via the Web at:
- </para>
- <para>
- <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.ietf.org/rfc/">http://www.ietf.org/rfc/</link>.
- </para>
+
<bibliography><title/>
<bibliodiv><title>Standards</title>
<!-- one of (BIBLIOENTRY BIBLIOMIXED) -->
</appendix>
<reference xml:id="Bv9ARM.ch13"><info><title>Manual pages</title></info>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dig/dig.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/mdig.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dig/host.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/arpaname.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/confgen/ddns-confgen.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/delv/delv.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dig/nslookup.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dig/dig.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/python/dnssec-checkds.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/python/dnssec-coverage.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dnssec/dnssec-dsfromkey.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dnssec/dnssec-settime.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dnssec/dnssec-signzone.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dnssec/dnssec-verify.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/dnstap-read.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/genrandom.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dig/host.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/isc-hmac-fixup.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/named/lwresd.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/named/named.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/named/named.conf.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/mdig.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/check/named-checkconf.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/check/named-checkzone.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/named-journalprint.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/named-nzd2nzf.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/named-rrchecker.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/named/named.conf.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/named/named.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/nsec3hash.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/dig/nslookup.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/nsupdate/nsupdate.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/rndc/rndc.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/rndc/rndc.conf.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/confgen/rndc-confgen.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/confgen/ddns-confgen.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/arpaname.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/dnstap-read.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/genrandom.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/isc-hmac-fixup.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/tools/nsec3hash.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/pkcs11/pkcs11-destroy.docbook"/>
- <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/pkcs11/pkcs11-list.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/pkcs11/pkcs11-keygen.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/pkcs11/pkcs11-list.docbook"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/pkcs11/pkcs11-tokens.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/confgen/rndc-confgen.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/rndc/rndc.conf.docbook"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="../../bin/rndc/rndc.docbook"/>
</reference>
</book>
projects / thirdparty / bind9.git / commitdiff
