# Listener Configuration Overview

A listener is configured with one or more listening protocol addresses and information about the destination service.

Protocol addresses are configured in the listener configuration file, listener.ora. Service information may or may not be configured in the `listener.ora` file:

- An Oracle8i database automatically registers certain information with the listener, such as its service name(s), instance name(s), service handlers, and load information. This feature, called service registration, does not require static configuration in the `listener.ora` file.

- Other services, including an Oracle7 or Oracle8 database and the Oracle Enterprise Manager management tools, require service configuration in the `listener.ora` file.

During installation, Net8 Configuration Assistant assumes you may use Oracle Enterprise Manager to monitor the database, so service information is configured statically in the `listener.ora` file.

The following `listener.ora` file shows a sample configuration. The LISTENER entry defines the listening protocol address for a listener named `LISTENER` and the SID_LIST_LISTENER entry provides information about the database service, including the global database name, the Oracle home location of the database, and the Oracle System Identifier (SID) of the instance.

       listener=
        (description=
         (address=(protocol=tcp)(host=sales-sun)(port=1521)))
       sid_list_listener=
        (sid_desc=
         (global_dbname=sales.us.acme.com)
         (oracle_home=/orahome81)
         (sid_name=sales))