Network Working Group D. Eastlake 3rd
Request for Comments: 5395 Stellar Switches
BCP: 42 November 2008
Obsoletes: 2929
Updates: 1183, 3597
Category: Best Current Practice
Domain Name System (DNS) IANA Considerations
Status of This Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
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Abstract
Internet Assigned Number Authority (IANA) parameter assignment
considerations are specified for the allocation of Domain Name System
(DNS) resource record types, CLASSes, operation codes, error codes,
DNS protocol message header bits, and AFSDB resource record subtypes.
Eastlake Best Current Practice [Page 1]
RFC 5395 DNS IANA Considerations November 2008
Table of Contents
1. Introduction ....................................................2
1.1. Terminology ................................................2
2. DNS Query/Response Headers ......................................3
2.1. One Spare Bit? .............................................4
2.2. OpCode Assignment ..........................................4
2.3. RCODE Assignment ...........................................4
3. DNS Resource Records ............................................6
3.1. RRTYPE IANA Considerations .................................7
3.1.1. DNS RRTYPE Allocation Policy ........................8
3.1.2. DNS RRTYPE Expert Guidelines ........................9
3.1.3. Special Note on the OPT RR ..........................9
3.1.4. The AFSDB RR Subtype Field .........................10
3.2. RR CLASS IANA Considerations ..............................10
3.3. Label Considerations ......................................12
3.3.1. Label Types ........................................12
3.3.2. Label Contents and Use .............................12
4. Security Considerations ........................................13
5. IANA Considerations ............................................13
Appendix A. RRTYPE Allocation Template ............................14
Normative References ..............................................15
Informative References ............................................16
1. Introduction
The Domain Name System (DNS) provides replicated distributed secure
hierarchical databases that store "resource records" (RRs) under
domain names. DNS data is structured into CLASSes and zones that can
be independently maintained. See [RFC1034], [RFC1035], [RFC2136],
[RFC2181], and [RFC4033], familiarity with which is assumed.
This document provides, either directly or by reference, the general
IANA parameter assignment considerations that apply across DNS query
and response headers and all RRs. There may be additional IANA
considerations that apply to only a particular RRTYPE or
query/response OpCode. See the specific RFC defining that RRTYPE or
query/response OpCode for such considerations if they have been
defined, except for AFSDB RR considerations [RFC1183], which are
included herein. This RFC obsoletes [RFC2929].
IANA currently maintains a web page of DNS parameters available from
http://www.iana.org.
1.1. Terminology
"IETF Standards Action", "IETF Review", "Specification Required", and
"Private Use" are as defined in [RFC5226].
Eastlake Best Current Practice [Page 2]
RFC 5395 DNS IANA Considerations November 2008
2. DNS Query/Response Headers
The header for DNS queries and responses contains field/bits in the
following diagram taken from [RFC2136] and [RFC2929]:
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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