This guide will step you through how to take an IP address, and find out what its reverse dns host name is. This is useful for checking mail server DNS setup, etc.
The DNS system works two ways. It is used to convert host names to IP addresses, but it can also convert IP addresses to host names.
Two handy programs to perform DNS queries on Linux are ‘dig’ and ‘host’. If either of these aren’t installed on your system, they should be available in your distributions repositories.
$ dig -x 184.108.40.206 +short
$ dig -x 220.127.116.11 +short google-public-dns-a.google.com. $
$ host 18.104.22.168
$ host 22.214.171.124 126.96.36.199.in-addr.arpa domain name pointer google-public-dns-a.google.com. $