-
-
DNS Extensions Working Group J. Schlyter, Ed.
-Internet-Draft December 19, 2003
-Updates: RFC 2535, RFC TCR (if approved)
-Expires: June 18, 2004
+Internet-Draft March 3, 2004
+Updates: RFC 2535, RFC TCR
+Expires: September 1, 2004
DNSSEC NSEC RDATA Format
- draft-ietf-dnsext-nsec-rdata-03.txt
+ draft-ietf-dnsext-nsec-rdata-04.txt
Status of this Memo
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
- This Internet-Draft will expire on June 18, 2004.
+ This Internet-Draft will expire on September 1, 2004.
Copyright Notice
- Copyright (C) The Internet Society (2003). All Rights Reserved.
+ Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
- This document defines updates the NSEC resource record RDATA format
- to cover all type codes.
-
+ This document redefines the wire format of the "Type Bit Map" field
+ in the NSEC resource record RDATA format to cover the full RR type
+ space.
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+Internet-Draft DNSSEC NSEC RDATA Format March 2004
Table of Contents
2.1.2 The List of Type Bit Map(s) Field . . . . . . . . . . . . . 4
2.1.3 Inclusion of Wildcard Names in NSEC RDATA . . . . . . . . . 5
2.2 The NSEC RR Presentation Format . . . . . . . . . . . . . . 5
- 2.3 NSEC RR Example . . . . . . . . . . . . . . . . . . . . . . 5
+ 2.3 NSEC RR Example . . . . . . . . . . . . . . . . . . . . . . 6
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . 6
Normative References . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
The NSEC [5] Resource Record (RR) is used for authenticated proof of
- the non-existence of DNS owner names and types. The RDATA format for
- the NSEC RR, as described in RFC 2535 [2], had a limitation in that,
- without using a yet undefined extension mechanism, the the RDATA
- could only carry information about the existence of the first 127
- types.
+ the non-existence of DNS owner names and types. The NSEC RR is based
+ on the NXT RR as described in RFC 2535 [2], and is similar except for
+ the name and typecode. The RDATA format for the NXT RR had a
+ limitation in that, without using a yet undefined extension
+ mechanism, the the RDATA could only carry information about the
+ existence of the first 127 types.
To prevent the introduction of an extension mechanism into a deployed
base of DNSSEC aware servers and resolvers, once the first 127 type
This document introduces a new format for the type bit map. The
properties of the type bit map format are that it can cover the full
- possible range of typecodes; that it is relatively economic in the
+ possible range of typecodes, that it is relatively economic in the
amount of space it uses for the common case of a few types with an
- owner name; that it can represent owner names with all possible type
- present in packets of approximately 8.5 kilobytes; that the
+ owner name, that it can represent owner names with all possible types
+ present in packets of approximately 8.5 kilobytes and that the
representation is simple to implement. Efficient searching of the
type bitmap for the presence of certain types is not a requirement.
[2] and as updated by RFC TCR [5], thereby not introducing changes
except for the syntax of the type bit map.
- [Editors note: this is the text that is to be copied into
- draft-ietf-dnssec-dnssec-records]
-
This document updates RFC 2535 [2] and RFC TCR [5].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
2. The NSEC Resource Record
The NSEC resource record lists two separate things: the owner name of
- the next authoritative RRset in the canonical ordering of the zone,
- and the set of RR types present at the NSEC RR's owner name. The
- complete set of NSEC RRs in a zone both indicate which authoritative
- RRsets exist in a zone and also form a chain of authoritative owner
- names in the zone. This information is used to provide authenticated
- denial of existence for DNS data, as described in RFC 2535 [2].
+ the next RRset in the canonical ordering of the zone, and the set of
+ RR types present at the NSEC RR's owner name. The complete set of
+ NSEC RRs in a zone both indicate which RRsets exist in a zone and
+ also form a chain of owner names in the zone. This information is
+ used to provide authenticated denial of existence for DNS data, as
+ described in RFC 2535 [2].
+ The type value for the NSEC RR is 47.
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- The type value for the NSEC RR is 47.
The NSEC RR RDATA format is class independent and defined for all
classes.
2.1.1 The Next Domain Name Field
- The Next Domain Name field contains the owner name of the next
- authoritative RRset in the canonical ordering of the zone. The value
- of the Next Domain Name field in the last NSEC record in the zone is
- the name of the zone apex (the owner name of the zone's SOA RR).
+ The Next Domain Name field contains the owner name of the next RR in
+ the canonical ordering of the zone. The value of the Next Domain
+ Name field in the last NSEC record in the zone is the name of the
+ zone apex (the owner name of the zone's SOA RR).
+
+ A sender MUST NOT use DNS name compression on the Next Domain Name
+ field when transmitting an NSEC RR. A receiver which receives an
+ NSEC RR containing a compressed Next Domain Name field SHOULD
+ decompress the field value.
+
+ Owner names of RRsets not authoritative for the given zone (such as
+ glue records) MUST NOT be listed in the Next Domain Name unless at
+ least one authoritative RRset exists at the same owner name.
2.1.2 The List of Type Bit Map(s) Field
"|" denotes concatenation
- Type Bit Map(s) Field = ( Window Block # | Bitmap Length | Bitmap ) +
- Each bitmap encodes the low-order 8 bits of RR types within the
- window block, in network bit order. The first bit is bit 0. For
- window block 0, bit 1 corresponds to RR type 1 (A), bit 2 corresponds
- to RR type 2 (NS), and so forth. For window block 1, bit 1
- corresponds to RR type 257, bit 2 to RR type 258. If a bit is set to
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+ Type Bit Map(s) Field = ( Window Block # | Bitmap Length | Bitmap ) +
+ Each bitmap encodes the low-order 8 bits of RR types within the
+ window block, in network bit order. The first bit is bit 0. For
+ window block 0, bit 1 corresponds to RR type 1 (A), bit 2 corresponds
+ to RR type 2 (NS), and so forth. For window block 1, bit 1
+ corresponds to RR type 257, bit 2 to RR type 258. If a bit is set to
1, it indicates that an RRset of that type is present for the NSEC
RR's owner name. If a bit is set to 0, it indicates that no RRset of
that type is present for the NSEC RR's owner name.
type mnemonics. When the mnemonic is not known, the TYPE
representation as described in RFC 3597 [4] (section 5) MUST be used.
-2.3 NSEC RR Example
- The following NSEC RR identifies the RRsets associated with
- alfa.example.com. and identifies the next authoritative name after
- alfa.example.com.
- alfa.example.com. 86400 IN NSEC host.example.com. A MX RRSIG NSEC TYPE1234
- The first four text fields specify the name, TTL, Class, and RR type
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+2.3 NSEC RR Example
+ The following NSEC RR identifies the RRsets associated with
+ alfa.example.com. and identifies the next authoritative name after
+ alfa.example.com.
+ alfa.example.com. 86400 IN NSEC host.example.com. A MX RRSIG NSEC TYPE1234
+
+ The first four text fields specify the name, TTL, Class, and RR type
(NSEC). The entry host.example.com. is the next authoritative name
- after alfa.example.com. in canonical order. The A, MX, RRSIG and NSEC
- mnemonics indicate there are A, MX, RRSIG, NSEC and TYPE1234 RRsets
- associated with the name alfa.example.com.
+ after alfa.example.com. in canonical order. The A, MX, RRSIG, NSEC
+ and TYPE1234 mnemonics indicate there are A, MX, RRSIG, NSEC and
+ TYPE1234 RRsets associated with the name alfa.example.com.
The RDATA section of the NSEC RR above would be encoded as:
4. Security Considerations
- The change introducted here does not affect security, since it only
- updates the RDATA format and encoding.
+ The update of the RDATA format and encoding does not affect the
+ security of the use of NSEC RRs.
Normative References
Levels", BCP 14, RFC 2119, March 1997.
[2] Eastlake, D., "Domain Name System Security Extensions", RFC
- 2535, March 1999.
- [3] Eastlake, D., Brunner-Williams, E. and B. Manning, "Domain Name
- System (DNS) IANA Considerations", BCP 42, RFC 2929, September
- 2000.
- [4] Gustafsson, A., "Handling of Unknown DNS Resource Record (RR)
- Types", RFC 3597, September 2003.
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+ 2535, March 1999.
-Internet-Draft DNSSEC NSEC RDATA Format December 2003
+ [3] Eastlake, D., Brunner-Williams, E. and B. Manning, "Domain Name
+ System (DNS) IANA Considerations", BCP 42, RFC 2929, September
+ 2000.
+ [4] Gustafsson, A., "Handling of Unknown DNS Resource Record (RR)
+ Types", RFC 3597, September 2003.
[5] Weiler, S., "Legacy Resolver Compatibility for Delegation
Signer", draft-ietf-dnsext-dnssec-2535typecode-change-05 (work
+Schlyter Expires September 1, 2004 [Page 7]
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Intellectual Property Statement
Full Copyright Statement
- Copyright (C) The Internet Society (2003). All Rights Reserved.
+ Copyright (C) The Internet Society (2004). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
-Schlyter Expires June 18, 2004 [Page 8]
+Schlyter Expires September 1, 2004 [Page 8]
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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