PTR Records and IPv6

Clients running Windows 7 do not try to register PTR records for IPv6 addresses assigned to interfaces on the computer. If you want to enable clients to perform reverse lookups for Windows 7 computers using IPv6, you must manually create a reverse lookup zone for the ip6.arpa domain on your DNS servers and then manually add PTR records to this zone. For detailed steps on how to do this, see "IPv6 for Microsoft Windows: Frequently Asked Questions" at http://www.microsoft.com/technet/network/ipv6/ipv6faq.mspx.

However, PTR records for reverse lookups using IPv6 are not often used, because the namespace for reverse queries is formed by using each hexadecimal digit in the colon-hexadecimal representation of an IPv6 address as a separate level in the reverse domain hierarchy. For example, the PTR record associated with the IPv6 address 2001:DB8::D3:00FF:FE28:9C5A, whose full representation is 2001:0DB8:0000 :0000:00D3:00FF:FE28:9C5A, would be expressed as A.5.C.9.8.2.E.F.F.F.0.0.3.D.0.0.0.0. 0.0.0.0.0.0.8.B.D.0.1.0.0.2.IP6.ARPA . The performance cost of resolving such a representation is generally too high for most DNS server implementations.