Abstract: In a Web on-demand system, even a client terminal whose IP address is not fixed can provide Web in response to an inquiry using a host name from a user terminal. A Web on-demand server receives, from a client terminal, client information including an IP address assigned to the client terminal by an Internet service provider and arbitrary host name, and transmits the client information to a DNS server to register the information. When the DNS server which maintains fully qualified domain names assigned by the Internet service provider receives an inquiry using a host name from a user terminal, it returns a corresponding IP address.