Domain Name System (DNS) IANA Considerations
RFC 2929
Document | Type |
RFC - Best Current Practice
(September 2000; No errata)
Obsoleted by RFC 5395
|
|
---|---|---|---|
Authors | Eric Brunner-Williams , Bill Manning , Donald Eastlake | ||
Last updated | 2013-03-02 | ||
Replaces | draft-eastlake-dnsext-2929bis | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 2929 (Best Current Practice) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group D. Eastlake, 3rd Request for Comments: 2929 Motorola BCP: 42 E. Brunner-Williams Category: Best Current Practice Engage B. Manning ISI September 2000 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. Copyright Notice Copyright (C) The Internet Society (2000). All Rights Reserved. Abstract Internet Assigned Number Authority (IANA) parameter assignment considerations are given for the allocation of Domain Name System (DNS) classes, Resource Record (RR) types, operation codes, error codes, etc. Table of Contents 1. Introduction................................................. 2 2. DNS Query/Response Headers................................... 2 2.1 One Spare Bit?.............................................. 3 2.2 Opcode Assignment........................................... 3 2.3 RCODE Assignment............................................ 4 3. DNS Resource Records......................................... 5 3.1 RR TYPE IANA Considerations................................. 6 3.1.1 Special Note on the OPT RR................................ 7 3.2 RR CLASS IANA Considerations................................ 7 3.3 RR NAME Considerations...................................... 8 4. Security Considerations...................................... 9 References...................................................... 9 Authors' Addresses.............................................. 11 Full Copyright Statement........................................ 12 Eastlake, et al. Best Current Practice [Page 1] RFC 2929 DNS IANA Considerations September 2000 1. Introduction The Domain Name System (DNS) provides replicated distributed secure hierarchical databases which hierarchically store "resource records" (RRs) under domain names. This data is structured into CLASSes and zones which can be independently maintained. See [RFC 1034, 1035, 2136, 2181, 2535] familiarity with which is assumed. This document covers, either directly or by reference, general IANA parameter assignment considerations applying across DNS query and response headers and all RRs. There may be additional IANA considerations that apply to only a particular RR type or query/response opcode. See the specific RFC defining that RR type or query/response opcode for such considerations if they have been defined. IANA currently maintains a web page of DNS parameters. See <http://www.iana.org/numbers.htm>. "IETF Standards Action", "IETF Consensus", "Specification Required", and "Private Use" are as defined in [RFC 2434]. 2. DNS Query/Response Headers The header for DNS queries and responses contains field/bits in the following diagram taken from [RFC 2136, 2535]: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | ID | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | QDCOUNT/ZOCOUNT | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | ANCOUNT/PRCOUNT | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | NSCOUNT/UPCOUNT | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | ARCOUNT | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ The ID field identifies the query and is echoed in the response so they can be matched. Eastlake, et al. Best Current Practice [Page 2] RFC 2929 DNS IANA Considerations September 2000 The QR bit indicates whether the header is for a query or a response. The AA, TC, RD, RA, AD, and CD bits are each theoretically meaningful only in queries or only in responses, depending on the bit. However, many DNS implementations copy the query header as the initial value of the response header without clearing bits. Thus any attempt to use a "query" bit with a different meaning in a response or to defineShow full document text