along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
-<refentry id="systemd-resolved.service" conditional='ENABLE_RESOLVED'>
+<refentry id="systemd-resolved.service" conditional='ENABLE_RESOLVE'>
<refentryinfo>
<title>systemd-resolved.service</title>
<itemizedlist>
<listitem><para>The native, fully-featured API <command>systemd-resolved</command> exposes on the bus. See the
- <ulink url="http://www.freedesktop.org/wiki/Software/systemd/resolved">API Documentation</ulink> for
+ <ulink url="https://www.freedesktop.org/wiki/Software/systemd/resolved">API Documentation</ulink> for
details. Usage of this API is generally recommended to clients as it is asynchronous and fully featured (for
example, properly returns DNSSEC validation status and interface scope for addresses as necessary for supporting
link-local networking).</para></listitem>
<listitem><para>The glibc
- <citerefentry><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</manvolnum></citerefentry> API (as defined
- by <ulink url="https://tools.ietf.org/html/rfc3493">RFC3493</ulink>) and its related resolver functions,
- including <citerefentry><refentrytitle>gethostbyname</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
+ <citerefentry project='man-pages'><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</manvolnum></citerefentry> API as defined
+ by <ulink url="https://tools.ietf.org/html/rfc3493">RFC3493</ulink> and its related resolver functions,
+ including <citerefentry project='man-pages'><refentrytitle>gethostbyname</refentrytitle><manvolnum>3</manvolnum></citerefentry>. This
API is widely supported, including beyond the Linux platform. In its current form it does not expose DNSSEC
validation status information however, and is synchronous only. This API is backed by the glibc Name Service
- Switch (<citerefentry><refentrytitle>nss</refentrytitle><manvolnum>5</manvolnum></citerefentry>). Usage of the
+ Switch (<citerefentry project='man-pages'><refentrytitle>nss</refentrytitle><manvolnum>5</manvolnum></citerefentry>). Usage of the
glibc NSS module <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>
is required in order to allow glibc's NSS resolver functions to resolve host names via
<command>systemd-resolved</command>.</para></listitem>
<listitem><para>Additionally, <command>systemd-resolved</command> provides a local DNS stub listener on IP
address 127.0.0.53 on the local loopback interface. Programs issuing DNS requests directly, bypassing any local
- API may be directed to this stub, in order to connect them <command>systemd-resolved</command>. Note however that
- it is strongly recommended that local programs use the glibc NSS or bus APIs instead (as described above), as
- various network resolution concepts (such as link-local addressing, or LLMNR Unicode domains) cannot be mapped to
- the unicast DNS protocol.</para></listitem>
+ API may be directed to this stub, in order to connect them to <command>systemd-resolved</command>. Note however
+ that it is strongly recommended that local programs use the glibc NSS or bus APIs instead (as described above),
+ as various network resolution concepts (such as link-local addressing, or LLMNR Unicode domains) cannot be mapped
+ to the unicast DNS protocol.</para></listitem>
</itemizedlist>
<para>The DNS servers contacted are determined from the global settings in
current gateway, useful for referencing it independently of the
current network configuration state.</para></listitem>
- <listitem><para>The mappings defined in <filename>/etc/hosts</filename> are resolved to their configured
- addresses and back.</para></listitem>
+ <listitem><para>The mappings defined in <filename>/etc/hosts</filename> are resolved
+ to their configured addresses and back, but they will not affect lookups for
+ non-address types (like MX).</para></listitem>
</itemizedlist>
<para>Lookup requests are routed to the available DNS servers
LLMNR.</para></listitem>
<listitem><para>Multi-label names are routed to all local
- interfaces that have a DNS sever configured, plus the globally
+ interfaces that have a DNS server configured, plus the globally
configured DNS server if there is one. Address lookups from the
link-local address range are never routed to
DNS.</para></listitem>
per-interface domains are exclusively routed to the matching
interfaces.</para>
- <para>See the <ulink url="http://www.freedesktop.org/wiki/Software/systemd/resolved"> resolved D-Bus API
+ <para>See the <ulink url="https://www.freedesktop.org/wiki/Software/systemd/resolved"> resolved D-Bus API
Documentation</ulink> for information about the APIs <filename>systemd-resolved</filename> provides.</para>
</refsect1>
<title><filename>/etc/resolv.conf</filename></title>
<para>Three modes of handling <filename>/etc/resolv.conf</filename> (see
- <citerefentry><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>) are
+ <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>) are
supported:</para>
<itemizedlist>
<varlistentry>
<term><constant>SIGUSR1</constant></term>
- <listitem><para>Upon reception of the SIGUSR1 process signal <command>systemd-resolved</command> will dump the
- contents of all DNS resource record caches it maintains into the system logs.</para></listitem>
+ <listitem><para>Upon reception of the <constant>SIGUSR1</constant> process signal
+ <command>systemd-resolved</command> will dump the contents of all DNS resource record caches it maintains into
+ the system logs.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>SIGUSR2</constant></term>
- <listitem><para>Upon reception of the SIGUSR2 process signal <command>systemd-resolved</command> will flush all
- caches it maintains. Note that it should normally not be necessary to request this explicitly – except for
- debugging purposes – as <command>systemd-resolved</command> flushes the caches automatically anyway any time
- the host's network configuration changes.</para></listitem>
+ <listitem><para>Upon reception of the <constant>SIGUSR2</constant> process signal
+ <command>systemd-resolved</command> will flush all caches it maintains. Note that it should normally not be
+ necessary to request this explicitly – except for debugging purposes – as <command>systemd-resolved</command>
+ flushes the caches automatically anyway any time the host's network configuration changes. Sending this signal
+ to <command>systemd-resolved</command> is equivalent to the <command>systemd-resolve --flush-caches</command>
+ command, however the latter is recommended since it operates in a synchronous way.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>SIGRTMIN+1</constant></term>
+
+ <listitem><para>Upon reception of the <constant>SIGRTMIN+1</constant> process signal
+ <command>systemd-resolved</command> will forget everything it learnt about the configured DNS
+ servers. Specifically any information about server feature support is flushed out, and the server feature
+ probing logic is restarted on the next request, starting with the most fully featured level. Note that it
+ should normally not be necessary to request this explicitly – except for debugging purposes – as
+ <command>systemd-resolved</command> automatically forgets learnt information any time the DNS server
+ configuration changes. Sending this signal to <command>systemd-resolved</command> is equivalent to the
+ <command>systemd-resolve --reset-server-features</command> command, however the latter is recommended since it
+ operates in a synchronous way.</para></listitem>
</varlistentry>
</variablelist>
+
</refsect1>
<refsect1>
projects / thirdparty / systemd.git / blobdiff