Reverse DNS Lookup
This tool will provide you the hostname (ie www.yahoo.com) of the IP address that you enter below.
Results:
Lookup on IPv4 Address: 12.204.16.2
Hostname: nagios.hartenergy.com
Hostname: nagios.hartenergy.biz
Hostname: smtp.hartenergy.biz
Hostname: postfix2.hartenergy.biz
Hostname: smtp.hartenergy.com
Hostname: cornbread.hartenergy.com
Hostname: cornbread.hartenergy.biz