The simplest way is to use the “host” utility provided by Gnu/Linux. Just run…
poison:~ # host 126.96.36.199
188.8.131.52.in-addr.arpa domain name pointer jc-in-f99.google.com.
This will query the name server and provide you with the hostname of the IP address.By default it will query the nameserver listed in the /etc/resolv.conf file.