Sample /etc/named.rev file
The in-addr.arpa domain was created because
Internet host addresses do not fall within domain boundaries.
This special domain allows inverse mapping: that of IP addresses
to domain names. The in-addr.arpa domain has
several labels preceding it -- an inverse reading of the host portion
of the host's Internet address.
For example, the host 132.147.118.1 is located in the domain
147.132.in-addr.arpa.
This reversal of the address is awkward to read but allows
for the natural grouping of hosts in a network.
The reverse hosts file, named.rev(SFF) (or databasename.rev), is a special hosts file for the reverse domain. As with all hosts files, it starts with SOA (start of authority) and NS (name server) records. These are followed by a series of PTR (pointer) records, each of which points from a reverse mapping of the machine's IP address to its hostname.
Here is a sample of mynet.rev:
; ; @(#)mynet.rev 2.0 94/05/27 ; @ IN SOA volga.mynet.COM. dave.mynet.COM ( 1993091901 ; Serial 10800 ; Refresh 1800 ; Retry 3600000 ; Expire 259200 ) ; Minimum IN NS volga.mynet.COM IN NS istanbul.mynet.COM 1.118 IN PTR volga.mynet.COM 2.118 IN PTR columbia.mynet.COM 3.118 IN PTR thames.mynet.COM 4.118 IN PTR seine.mynet.COM 5.118 IN PTR yangtze.mynet.COM 6.118 IN PTR mekong.mynet.COM ; additional addresses to follow in the same format 1.246 IN PTR volga.mynet.COM 2.246 IN PTR london.mynet.COM 3.246 IN PTR paris.mynet.COM ; additional addresses to follow in the same format