1. A method, comprising: receiving from a client, using at least one computer, a request to register an expression defining a set of domain names as associated with a single IP address in a domain name system for a wide area network, wherein the set includes more than one unique root domain member; evaluating the request using at least one computer, thereby determining registrability of the set of domain names; registering the expression in a data file of the domain name system for use in providing the IP address in response to information requests specifying a domain name belonging to the set of domain names.