Configure listener.ora, add database service

Oracle Net Listener settings can be stored in a text file named listener.ora. In most installations, the file is located under $ORACLE_HOME/network/admin. On Windows, the exact path varies by install, but it typically ends with \network\admin.

In older Oracle versions (and in many legacy tutorials), adding a database meant adding a static entry under a SID_LIST_<listener_name> heading. In modern Oracle releases, the normal approach is dynamic service registration: you keep listener.ora focused on the listener’s network address (host/port), and you ensure the database instance registers its services with that listener.

This lesson shows both approaches:

1. Historical context: How a legacy SID_LIST_LISTENER block is structured (with a single annotated image).
2. Current best practice: How to “add a database” in Oracle 23c by enabling/validating dynamic registration.
3. When static entries are still valid: Cases where a SID_LIST_... entry is still required (for example, external procedures).

In Oracle 23c-era configurations, you usually do not add a new database by copying SID_DESC blocks. Instead, you make sure the database (and its services) register with the listener. Conceptually, you are “adding” the database by ensuring the listener can see the service.

Step 1: Verify listener address (listener.ora)

Ensure your listener is configured to listen on the correct host and port. A minimal example looks like this:

LISTENER=
  (DESCRIPTION=
    (ADDRESS=(PROTOCOL=TCP)(HOST=sale-server)(PORT=1521))
  )

If you are using external procedures, keep the IPC address as well:

LISTENER=
  (DESCRIPTION=
    (ADDRESS=(PROTOCOL=TCP)(HOST=sale-server)(PORT=1521))
    (ADDRESS=(PROTOCOL=IPC)(KEY=extproc))
  )

Step 2: Ensure the database registers its service

From SQL*Plus (or SQLcl) as SYSDBA, validate the service configuration. In a multitenant environment, you typically connect users to a service name (often a PDB service), not a SID.

-- Quick checks (names vary by environment)
SHOW PARAMETER service_names
SHOW PARAMETER local_listener

If the listener is not on the default host/port (or you have a custom listener name), set LOCAL_LISTENER and force re-registration:

ALTER SYSTEM SET local_listener='(ADDRESS=(PROTOCOL=TCP)(HOST=sale-server)(PORT=1521))' SCOPE=BOTH;
ALTER SYSTEM REGISTER;

Step 3: Confirm the listener sees the service

On the database host, confirm registration from the OS:

lsnrctl status
lsnrctl services

You should see your database service(s) listed. If you do not, typical causes include: wrong host/port, DNS/hosts mismatch, firewall, listener started under a different Oracle home, or a missing/incorrect LOCAL_LISTENER value.

Static service registration (SID_LIST_...) is still used in specific scenarios, such as external procedures (extproc) and certain management/monitoring setups. In those cases, you can add a static entry for a database service.

Example: a static database entry (use only when you have a clear requirement):

SID_LIST_LISTENER=
  (SID_LIST=
    (SID_DESC=
      (GLOBAL_DBNAME = sales.us.example.com)
      (ORACLE_HOME   = /oracle23c)
      (SID_NAME      = sales)
    )
  )

Editing tip: the most common failure is broken parenthesis nesting. If you copy/paste, re-check indentation and matching parentheses before restarting the listener.

Click the exercise link below to add an entry for the COIN database to your listener.ora file.
Configuring Listener - Exercise

[1] listener.ora: A configuration file that defines Oracle Net Listener properties (addresses/ports, optional static services, and control parameters).