Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS)
RFC 3363
Document | Type |
RFC - Informational
(August 2002; No errata)
Updated by RFC 6672
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Authors | Randy Bush , Alain Durand , Bill Fink , Ólafur Guðmundsson , Tony Hain | ||
Last updated | 2020-07-29 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3363 (Informational) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Thomas Narten | ||
IESG note | Published as RFC 3363 and 3364 | ||
Send notices to | <okolkman@ripe.net> |
Network Working Group R. Bush Request for Comments: 3363 A. Durand Updates: 2673, 2874 B. Fink Category: Informational O. Gudmundsson T. Hain Editors August 2002 Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS) Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Abstract This document clarifies and updates the standards status of RFCs that define direct and reverse map of IPv6 addresses in DNS. This document moves the A6 and Bit label specifications to experimental status. 1. Introduction The IETF had begun the process of standardizing two different address formats for IPv6 addresses AAAA [RFC1886] and A6 [RFC2874] and both are at proposed standard. This had led to confusion and conflicts on which one to deploy. It is important for deployment that any confusion in this area be cleared up, as there is a feeling in the community that having more than one choice will lead to delays in the deployment of IPv6. The goal of this document is to clarify the situation. This document also discusses issues relating to the usage of Binary Labels [RFC 2673] to support the reverse mapping of IPv6 addresses. This document is based on extensive technical discussion on various relevant working groups mailing lists and a joint DNSEXT and NGTRANS meeting at the 51st IETF in August 2001. This document attempts to capture the sense of the discussions and reflect them in this document to represent the consensus of the community. Bush, et. al. Informational [Page 1] RFC 3363 Representation of IPv6 Addresses in DNS August 2002 The main arguments and the issues are covered in a separate document [RFC3364] that reflects the current understanding of the issues. This document summarizes the outcome of these discussions. The issue of the root of reverse IPv6 address map is outside the scope of this document and is covered in a different document [RFC3152]. 1.1 Standards Action Taken This document changes the status of RFCs 2673 and 2874 from Proposed Standard to Experimental. 2. IPv6 Addresses: AAAA RR vs A6 RR Working group consensus as perceived by the chairs of the DNSEXT and NGTRANS working groups is that: a) AAAA records are preferable at the moment for production deployment of IPv6, and b) that A6 records have interesting properties that need to be better understood before deployment. c) It is not known if the benefits of A6 outweigh the costs and risks. 2.1 Rationale There are several potential issues with A6 RRs that stem directly from the feature that makes them different from AAAA RRs: the ability to build up addresses via chaining. Resolving a chain of A6 RRs involves resolving a series of what are nearly-independent queries. Each of these sub-queries takes some non-zero amount of time, unless the answer happens to be in the resolver's local cache already. Other things being equal, we expect that the time it takes to resolve an N-link chain of A6 RRs will be roughly proportional to N. What data we have suggests that users are already impatient with the length of time it takes to resolve A RRs in the IPv4 Internet, which suggests that users are not likely to be patient with significantly longer delays in the IPv6 Internet, but terminating queries prematurely is both a waste of resources and another source of user frustration. Thus, we are forced to conclude that indiscriminate use of long A6 chains is likely to lead to increased user frustration. Bush, et. al. Informational [Page 2] RFC 3363 Representation of IPv6 Addresses in DNS August 2002 The probability of failure during the process of resolving an N-link A6 chain also appears to be roughly proportional to N, since each of the queries involved in resolving an A6 chain has roughly the same probability of failure as a single AAAA query. Last, several of the most interesting potential applications for A6 RRs involve situations where the prefix name field in the A6 RR points to a target that is not only outside the DNS zone containing the A6 RR, but is administered by a different organization entirely. While pointers out of zone are not a problem per se, experience bothShow full document text