Setting up reverse DNS

All IP addresses have a delegated DNS server that is used to provide the reverse DNS information.

To find ou which DNS server is the authoarative one for your IP you can use nslookup:

nslookup
set type=SOA
8.8.8.8

Will then return the authorative nameserver - we will then need to request an PTR record is added for us (assuming we don't have access to the DNS server!)

For example:
8.8.8.in-addr.arpa. 900    IN    PTR    mailserver.example.com.