Configuring Reverse DNS
You can configure Reverse DNS by having the Reverse DNS zone for your network delegated to your nameserver. Reverse DNS zones reside in the in-addr.arpa domain, and work in a similar way to Forward DNS zones. Zone names consist of the Network Address - with octets listed in reverse order - followed by in-addr.arpa. For example, the Reverse DNS zone for the network 208.94.147.96 is 147.94.208.in-addr.arpa.
Before attempting to configure Reverse DNS, you should have a good familiarity with the way DNS works, and with your nameserver software.
After creating a DNS zone file using the Reverse DNS zone name delegated to you, you need to create a PTR record that points this reverse IP back to the domain it's assigned to. This is done similar to creating an A Record
Your PTR Record should look similar to this:
Name - 96 (this is the last octet of the forward IP, or the first octet of the reverse IP)
This is followed by the rest of the zone name - 147.94.208.in-addr.arpa.
PTR To - www.dnsmadeeasy.com
Thus, you end up with a record that points 96.147.94.208.in-addr.arpa to www.dnsmadeeasy.com.