A method and system for resolving domain names of web sites with dynamic addresses. The resolution system, which may execute as part of a domain name server, receives a domain name associated with a web site. The resolution system then identifies a dynamic address name associated with the received domain name. The resolution system then sends to a dynamic address system the identified dynamic address name. The dynamic address system then returns an address associated with the dynamic address name to the resolution system. Upon receiving the identified address, the resolution system then returns the identified address as the address of the received domain name. Methods and systems for mapping an unregistered domain name to an address and for placing telephone calls via a network are also provided.