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Network Working Group                                         S. ThomsonRequest for Comments: 1886                                      BellcoreCategory: Standards Track                                     C. Huitema                                                                   INRIA                                                           December 1995DNS Extensions to support IP version 6Status 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.Abstract   This document defines the changes that need to be made to the Domain   Name System to support hosts running IP version 6 (IPv6).  The   changes include a new resource record type to store an IPv6 address,   a new 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.Thompson & Huitema          Standards Track                    [Page 1]

RFC 1886                  IPv6 DNS Extensions              December 19951. INTRODUCTION   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 we define the following   extensions:      o A new resource record type is defined to map a domain name to an        IPv6 address.      o A new 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 DNS   are discussed in [4].2. NEW RESOURCE RECORD DEFINITION AND DOMAIN   A new record type is defined to store a host's IPv6 address. A host   that has more than one IPv6 address must have more than one such   record.2.1 AAAA record type   The AAAA resource record type is a new record specific to the   Internet class that stores a single IPv6 address.   The value of the type is 28 (decimal).2.2 AAAA data format   A 128 bit IPv6 address is encoded in the data portion of an AAAA   resource record in network byte order (high-order byte first).Thompson & Huitema          Standards Track                    [Page 2]

RFC 1886                  IPv6 DNS Extensions              December 19952.3 AAAA query   An AAAA query for a specified domain name in the Internet class   returns all associated AAAA resource records in the answer section of   a response.   A type AAAA query does not perform additional section processing.2.4 Textual format of AAAA records   The textual representation of the data portion of the AAAA resource   record used in a master database file is the textual representation   of a IPv6 address as defined in [3].2.5 IP6.INT Domain   A special domain is defined to look up a record given an 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.INT.   An IPv6 address is represented as a name in the IP6.INT domain by a   sequence of nibbles separated by dots with the suffix ".IP6.INT". 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 inverse lookup domain name corresponding to the address       4321:0:1:2:3:4:567:89ab   would beb.a.9.8.7.6.5.0.4.0.0.0.3.0.0.0.2.0.0.0.1.0.0.0.0.0.0.0.1.2.3.4.IP6.INT.3. MODIFICATIONS TO EXISTING QUERY TYPES   All existing query types that perform type A additional section   processing, i.e. name server (NS), mail exchange (MX) and mailbox   (MB) query types, must be redefined to perform both type A and type   AAAA additional section processing. These new definitions mean that a   name server must add any relevant IPv4 addresses and any relevantThompson & Huitema          Standards Track                    [Page 3]

RFC 1886                  IPv6 DNS Extensions              December 1995   IPv6 addresses available locally to the additional section of a   response when processing any one of the above queries.4. SECURITY CONSIDERATIONS   Security issues are not discussed in this memo.Thompson & Huitema          Standards Track                    [Page 4]

RFC 1886                  IPv6 DNS Extensions              December 19955. REFERENCES   [1]  Mockapetris, P., "Domain Names - Concepts and Facilities", STD        13,RFC 1034, USC/Information Sciences Institute, November 1987.   [2]  Mockapetris, P., "Domain Names - Implementation and Specifica-        tion", STD 13,RFC 1035, USC/Information Sciences Institute,        November 1987.   [3]  Hinden, R., and S. Deering, Editors, "IP Version 6 Addressing        Architecture",RFC 1884, Ipsilon Networks, Xerox PARC, December        1995.   [4]  Gilligan, R., and E. Nordmark, "Transition Mechanisms for IPv6        Hosts and Routers", Work in Progress.Authors' Addresses   Susan Thomson   Bellcore   MRE 2P343   445 South Street   Morristown, NJ 07960   U.S.A.   Phone: +1 201-829-4514   EMail: set@thumper.bellcore.com   Christian Huitema   INRIA, Sophia-Antipolis   2004 Route des Lucioles   BP 109   F-06561 Valbonne Cedex   France   Phone: +33 93 65 77 15   EMail: Christian.Huitema@MIRSA.INRIA.FRThompson & Huitema          Standards Track                    [Page 5]