Network Working Group S. Thomson Request for Comments: 3596 Cisco Obsoletes: 3152, 1886 C. Huitema Category: Standards Track Microsoft V. Ksinant 6WIND M. Souissi AFNIC October 2003
DNS Extensions to Support IP Version 6
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document defines the changes that need to be made to the Domain Name System (DNS) to support hosts running IP version 6 (IPv6). The changes include a resource record type to store an IPv6 address, a domain to support lookups based on an IPv6 address, and updated definitions of existing query types that return Internet addresses as part of additional section processing. The extensions are designed to be compatible with existing applications and, in particular, DNS implementations themselves.
Current support for the storage of Internet addresses in the Domain Name System (DNS) [1,2] cannot easily be extended to support IPv6 addresses [3] since applications assume that address queries return 32-bit IPv4 addresses only.
To support the storage of IPv6 addresses in the DNS, this document defines the following extensions:
o A resource record type is defined to map a domain name to an IPv6 address.
o A domain is defined to support lookups based on address.
o Existing queries that perform additional section processing to locate IPv4 addresses are redefined to perform additional section processing on both IPv4 and IPv6 addresses.
The changes are designed to be compatible with existing software. The existing support for IPv4 addresses is retained. Transition issues related to the co-existence of both IPv4 and IPv6 addresses in the DNS are discussed in [4].
The IP protocol version used for querying resource records is independent of the protocol version of the resource records; e.g., IPv4 transport can be used to query IPv6 records and vice versa.
This document combines RFC 1886 [5] and changes to RFC 1886 made by RFC 3152 [6], obsoleting both. Changes mainly consist in replacing the IP6.INT domain by IP6.ARPA as defined in RFC 3152.
The textual representation of the data portion of the AAAA resource record used in a master database file is the textual representation of an IPv6 address as defined in [3].
A special domain is defined to look up a record given an IPv6 address. The intent of this domain is to provide a way of mapping an IPv6 address to a host name, although it may be used for other purposes as well. The domain is rooted at IP6.ARPA.
An IPv6 address is represented as a name in the IP6.ARPA domain by a sequence of nibbles separated by dots with the suffix ".IP6.ARPA". The sequence of nibbles is encoded in reverse order, i.e., the low-order nibble is encoded first, followed by the next low-order nibble and so on. Each nibble is represented by a hexadecimal digit. For example, the reverse lookup domain name corresponding to the address
All existing query types that perform type A additional section processing, i.e., name server (NS), location of services (SRV) and mail exchange (MX) query types, must be redefined to perform both type A and type AAAA additional section processing. These definitions mean that a name server must add any relevant IPv4 addresses and any relevant IPv6 addresses available locally to the additional section of a response when processing any one of the above queries.
Any information obtained from the DNS must be regarded as unsafe unless techniques specified in [7] or [8] are used. The definitions of the AAAA record type and of the IP6.ARPA domain do not change the model for use of these techniques.
So, this specification is not believed to cause any new security problems, nor to solve any existing ones.
The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director.
Thomson, et al. Standards Track [Page 4]
RFC 3596 DNS Extensions to Support IPv6 October 2003
Acknowledgments
Vladimir Ksinant and Mohsen Souissi would like to thank Sebastien Barbin (IRISA), Luc Beloeil (France Telecom R&D), Jean-Mickael Guerin (6WIND), Vincent Levigneron (AFNIC), Alain Ritoux (6WIND), Frederic Roudaut (IRISA) and G6 group for their help during the RFC 1886 Interop tests sessions.
Many thanks to Alain Durand and Olafur Gudmundsson for their support.
Thomson, et al. Standards Track [Page 5]
RFC 3596 DNS Extensions to Support IPv6 October 2003
RFC 3596 DNS Extensions to Support IPv6 October 2003
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