RFC 1886

DNS Extensions to support IP version 6

📅 published December 1995, from ietf

RFC 1886: DNS Extensions to support IP version 6 🌸

  • RFC number: 1886
  • Title: DNS Extensions to support IP version 6
  • Authors: S. Thomson (Bellcore) and C. Huitema (INRIA), both in the Network Working Group 💖
  • Category: Standards Track 🎀
  • Date: December 1995 📅
  • Obsoletes / Updates: nothing is listed in its header 🙈

Status of This Memo 📜

Okay so this doc is an Internet standards track protocol for the Internet community, and it's openly asking for discussion and suggestions for improvements 🫶. For the current standardization state and status of this protocol, check the "Internet Official Protocol Standards" (STD 1) list ✨. Distribution of this memo is unlimited 🌈.

Abstract 🦋

This doc spells out the changes DNS needs so hosts running IP version 6 (IPv6) can actually work 💅. It adds a new resource record type to store an IPv6 address, a new domain for lookups based on an IPv6 address, and updated definitions of the existing query types that return Internet addresses during additional section processing 🔥. Everything is designed to be compatible with existing applications and especially with DNS implementations themselves 🧚.

1. INTRODUCTION 🌷

Right now DNS can store Internet addresses [1,2], but you can't just bolt IPv6 addresses [3] on, because applications assume address queries only return 32-bit IPv4 addresses 🙈. So we define three things:

  • A new resource record type that maps a domain name to an IPv6 address.
  • A new domain that supports lookups based on address.
  • Existing queries that do additional section processing to find IPv4 addresses get redefined to do additional section processing on both IPv4 and IPv6 addresses.

These changes are built to be compatible with existing software, and the existing support for IPv4 addresses stays right where it is 💜. Transition issues around IPv4 and IPv6 addresses coexisting in DNS are discussed in [4] 🦄.

2. NEW RESOURCE RECORD DEFINITION AND DOMAIN 🍓

A new record type stores a host's IPv6 address 🌸. A host with more than one IPv6 address must have more than one such record, so no shortcuts 👑.

2.1 AAAA record type 💫

The AAAA resource record type is a brand new record, specific to the Internet class, and it stores a single IPv6 address 💖. Its type value is 28 (decimal) ✨.

2.2 AAAA data format 🎀

A 128 bit IPv6 address goes in the data portion of an AAAA resource record in network byte order (high-order byte first) 🔥.

2.3 AAAA query 🔍

An AAAA query for a specified domain name in the Internet class returns all the associated AAAA resource records in the answer section of a response 🫶. A type AAAA query does not perform additional section processing, so it's a clean, no-extras kind of query 💅.

2.4 Textual format of AAAA records 📝

The textual representation of the data portion of an AAAA resource record in a master database file is the textual representation of an IPv6 address as defined in [3] 🌈.

2.5 IP6.INT Domain 🧚

There's a special domain for looking up a record given an address 🔎. The intent is mapping an IPv6 address to a host name, though 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 as a sequence of nibbles separated by dots, with the suffix .IP6.INT. The nibbles are encoded in reverse order, so the low-order nibble comes first, then the next low-order nibble, and so on. Each nibble is represented by a hexadecimal digit 🧮. For example, the inverse lookup domain name for the address:

4321:0:1:2:3:4:567:89ab

would be:

b.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 the existing query types that do type A additional section processing, meaning the 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 relevant 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. 💀 Read that with full seriousness, bestie.

5. 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 Specification", 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 🌸

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 💜

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.FR
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