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: 138.246.224.65
Hostname: lll.tum.de
Hostname: api.lll.tum.de
Hostname: www.lll.tum.de
Hostname: new.lll.tum.de
Hostname: tuwic03-website.srv.mwn.de