RFC 3363 (rfc3363) - Page 2 of 6
Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS)
Alternative Format: Original Text Document
RFC 3363 Representation of IPv6 Addresses in DNS August 2002 The main arguments and the issues are covered in a separate document [RFC 3364] 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 [RFC 3152]. 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
