Book Image

DNS in Action

By : CP Books a.s.
Book Image

DNS in Action

By: CP Books a.s.

Overview of this book

The Domain Name System is one of the foundations of the internet. It is the system that allows the translation of human-readable domain names into machines-readable IP addresses and the reverse translation of IP addresses into domain names. This book describes the basic DNS protocol and its extensions; DNS delegation and registration, including for reverse domains; using DNS servers in networks that are not connected to the internet; and using DNS servers on firewall machines. Many detailed examples are used throughout the book to show perform various configuration and administration tasks.
Table of Contents (16 chapters)
DNS in Action
About the Authors
Country Codes and RIRs

3.5 DNS IP version 6 Extension

DNS extension for IP version 6 is defined by RFC 1886, which was later amended and partially replaced by RFC 2874.

3.5.1 AAAA Records

IP version 4 uses the A record for the translation of a name into an IP address. The AAAA record was initially introduced for IP version 6. The difference is that the AAAA record has in the IP address field a 16-byte IP version 6 address and not a 4-byte address. The use of the AAAA record will not prevail in the future, though.

3.5.2 A6 Records

RFC 2874 replaces the AAAA record with the A6 record.

The A6 record is used for interfaces using IP version 6 addressing. Where an A record has an IP address, the RDATA field of the A6 record has, for example, the following form:

64 ::1244:67E3:589A:9ABC

with 64 being the prefix length (number of prefix bits), ::1244:67E3:589A:9ABC being the final part of the address suffix, and being the prefix name. Therefore the complete A6 record may look as follows: