There are only small differences between "address" records for IPv4 addresses and IPv6 addresses. A hostname with an IPv4 address would look this in a DNS zone file:

hostname        IN      A       172.27.16.31

This is called an "A record," where the A represents the word address. With IPv6, a new record type, AAAA (sometimes pronounced "quad-A"), was introduced. The name comes from the fact that an IPv6 address is four times as long as an IPv4 address. In a DNS zone file, it looks like this:

hostname        IN      AAAA    fec0::1f:7

Since IPv6-capable hosts at MTU will likely be "dual-stack" (both IPv4 and IPv6 enabled) for some time to come, those hostnames will have both kinds of records, such as

hostname        IN      A       172.27.16.31
                IN      AAAA    fec0::1f:7

Other types of records with names on the left-hand side of a DNS entry, such as CNAME, MX, NS, etc., work the same.

IPv4 addresses are matched to their hostnames with PTR records in the in-addr.arpa hierarchy. Since DNS hierarchy works in the opposite direction from IP-address hierarchy, the order of the address's bytes is reversed. For example,

31.16.27.172.in-addr.arpa.  IN  PTR  hostname.example.com.

IPv6 PTR records are handled somewhat differently. Instead of decimal bytes in reverse order in the in-addr.arpa hierarchy, IPv6 addresses are represented as hexadecimal "nybbles" (4-bit value, or one hexadecimal digit) in reverse order, and the hierarchy is ip6.arpa. The example IPv6 address above would appear on the left-hand side of a PTR record as 7.0.0.0.f.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.c.e.f.ip6.arpa. Unlike when representing an IPv6 address in its normal format, no compression of long strings of zeroes is permitted in PTR records.

Note: The ip6.arpa DNS PTR hierarchy has replaced the original ip6.int hierarchy, but some older resolvers, such as the one in Solaris 8, still use ip6.int. MTU's origin nameserver no longer serves an ip6.int zone and will not do so unless demand arises. Our reverse zone is 0.0.8.a.8.4.1.0.0.2.ip6.arpa. This zone may, in the distant future, be broken into several if the single zone file becomes excessively large.