Oracle Database Listener Service Registration

• I do not have listener.ora file. How is service registration working:

Service registration can happen dynamically or statically. By default, listener uses dynamic service registration before attempting static registration. For dynamic configuration, listener.ora file is not needed.

Dynamic service registration is configured in the database initialization file. It does not require any configuration in the listener.ora file.  For dynamic registration to work, you should set service_names and instance_names in init.ora. or it defaults to default value (INSTANCE_NAME is set to ORACLE_SID and service_names is set to global database name: DB_NAME +DB_DOMAIN). If your local listener is listening on a non-default port, you need to set LOCAL_LISTENER parameter and remote_listener ,typically used in RAC, needs to set with remote_listener parameter.

Additional info: http://docs.oracle.com/cd/E11882_01/network.112/e10836/listenercfg.htm#i490264

The static configuration reads information from listener.ora file to configure the services. An instance with status UNKNOWN is statically registered. For additional info check out the following:

http://www.oaktable.net/content/little-things-worth-knowing-static-and-dynamic-listener-registration

• How do I know which naming method is being used to connect:

Tnsping utility can be used to determine whether the listener for a service on an Oracle net network can be reached.

If you can ping the server host from client, use tnsping to test if client can reach Oracle net service. Tnsping also states the naming method which was used to connect.

Additional info:

http://edstevensdba.wordpress.com/2011/02/16/sqlnet_client_cfg/

http://edstevensdba.wordpress.com/2011/03/19/ora-12514/ ( look for all post under TNS category)