A client application can connect to an AppServer without specifying an application service. In this case, the NameServer uses whatever AppServer registers itself as the default service. You can specify any AppServer instance as the default service during AppServer configuration. However, Progress Software Corporation recommends that you avoid relying on the default service and provide explicit application service names for all AppServer instances that rely on a controlling NameServer for client connections. For more information on AppServer configuration, see OpenEdge Application Server: Administration.