The first item of the UAN specifies the name of the protocol used; the second item specifies the name and port number of the machine where the Naming Server resides. This name is usually a name that can be decoded by a domain name server. You can also use the IP of the machine, but it should be avoided. The last item specifies the relative name of the actor. If a port number is not specified, the default port number (3030) for the name server is used.