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 subnet.isp.com

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

www...