Whois

The whois tool can be used to find information about the administrator of domain or IP address range.

Domain example:

Those queries should get some good results.

The other way to use whois is to query about an IP address, or range. If you want to know who the IP in question has been assigned to, do this: This works just as well if you know the range... just input an IP in the range, even the network number itself, like 129.128.0.0 like the above example.