The server refuses a request to start a client session because the client node name is not registered in the server database.
Server operation continues.
Register the node name with the server before establishing a session. If the server is running with OPEN registration, no action is required; the client prompts the user for a password and registers the client with the server. If CLOSED registration is in effect on the server, an authorized administrator must use the REGISTER NODE command to register the client node name with the server.