what is the purpose of reverse dns lookup
Reverse DNS. Reverse DNS is IP address to domain name mapping-the opposite of forward (normal) DNS which maps domain names to IP addresses. Reverse DNS is separate from forward DNS.he name of the PTR-record is the IP address with the segments reversed + .in-addr.arpa. For example the reverse DNS entry for IP 1.2.3.4 would be stored as a PTR-record for 4.3.2.1.in-addr.arpa.