Thin and thick data models are used to store Whois information. A thin Whois lookup provides the registrar, name servers, and registration dates. For additional information, it's necessary to perform a further lookup, this time at the registrar on file, to get hold of complete information on the domain name ownership. A thick Whois lookup provides additional information beyond what's available from a thin Whois record. The extra details may contain contact information (registrant, administrative, and technical). A thick lookup supplies all the necessary information on who registered the domain name, where and when it was registered, the expiry date, and the nameservers it uses.