Application-oriented name registration system for used in multi-layer network address translator environment and the method thereof

An application-oriented name registration system for used in multi-layer network address translator environment, a logon method and a query method are provided, said multi-layer network address translator environment includes a public network and at least a private network, and said private network accesses the public network and other private networks via the network address translation unit, said name registration system includes a system terminal device, a calling agent server and a registration service device which accesses the public network and at least a private network; application of the present invention enables the application, service, user to be located by the ID in the multi-layer NAT network environment.