Domain Lookup is also known as a "whois" search since it access information on "whois" the owner of the domain, as well as other information, such as date created, expiration date, name servers, and information about the domain owner.
What is a Whois listing?
A Whois listing contains information associated with a domain name, such as its creation and expiration dates, the registrar of record, and various contacts (administrative, technical, etc.). Whois data is collected when a domain name is registered and is public information. The Whois information appears whenever a person conducts a Whois search on a particular domain name. All information entered in the Whois must be valid.
Another useful domain lookup is at Internic