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: 129.217.205.12
Hostname: dc2.tu-dortmund.de
Hostname: DomainDnsZones.tu-dortmund.de
Hostname: ForestDnsZones.tu-dortmund.de