WHOIS Lookup Utility
(Example: domain.com)
A note about WHOIS:

With the new shared registration system model, the nature of the WHOIS server has changed. Traditionally, the InterNIC maintained the WHOIS server for .com, .net and .org domain names, and a single query returned full whois data including registrant, administrative contact, billing contact, technical contact, and nameserver information. Under the new system, the registry WHOIS simply contains information on which Registrar is authoritative for a given domain.