Domain Name System (DNS) IANA Considerations
RFC 6195

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Internet Engineering Task Force (IETF)                   D. Eastlake 3rd
Request for Comments: 6195                                        Huawei
BCP: 42                                                       March 2011
Obsoletes: 5395
Updates: 1183, 3597
Category: Best Current Practice
ISSN: 2070-1721

              Domain Name System (DNS) IANA Considerations

Abstract

   This document specifies Internet Assigned Number Authority (IANA)
   parameter assignment considerations 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.

Status of This Memo

   This memo documents an Internet Best Current Practice.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   BCPs is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6195.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Eastlake 3rd              Best Current Practice                 [Page 1]
RFC 6195                 DNS IANA Considerations              March 2011

Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................3
   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
   Appendix B. Changes from RFC 5395 .................................15
   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.  Familiarity with  [RFC1034], [RFC1035],
   [RFC2136], [RFC2181], and [RFC4033] 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 [RFC5395]; however, the only
   significant change is the change to the public review mailing list to
   dnsext@ietf.org.

   IANA currently maintains a web page of DNS parameters available from
   http://www.iana.org.

Eastlake 3rd              Best Current Practice                 [Page 2]
RFC 6195                 DNS IANA Considerations              March 2011

1.1.  Terminology

   "Standards Action", "IETF Review", "Specification Required", and