OracleNet Complete Guide: Comprehensive Explanation of Listener Dynamic Configuration

Understanding how to configure the Oracle database listener is crucial for effective database management. Dynamic listener configuration, in particular, is frequently utilized in daily operations. This article thoroughly explains the mechanisms, setup steps, and verification methods for dynamic listener configuration.

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What is Dynamic Listener Configuration?
Benefits of Dynamic Configuration
How Dynamic Configuration Works
1. Default Listener Dynamic Configuration
Steps for Dynamic Configuration
Verifying Dynamic Configuration
Points to Note for Dynamic Configuration
1. Causes and Solutions for Dynamic Registration Failure
Differences Between Static and Dynamic Configuration
Summary

What is Dynamic Listener Configuration?

Dynamic listener configuration is a feature whereby Oracle databases automatically register their service information with the listener upon startup. This eliminates the need for administrators to manually edit the listener.ora file.

Text Diagram:

Oracle Database Startup
     │
     │ Automatically registers service information
     ▼
Listener
     │
     ▼
Client

Benefits of Dynamic Configuration

No manual editing of listener.ora required
Easy addition or modification of services
Streamlined daily operational management

How Dynamic Configuration Works

By default, the listener waits on TCP port 1521. When an Oracle instance starts, it automatically connects to the listener and registers service and instance information.

Default Listener Dynamic Configuration

When using the default listener (port 1521), you do not need to create the listener.ora file. The Oracle database automatically registers itself with the listener without additional configuration.

If you choose to use listener.ora, the minimal configuration example is as follows:

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
  )

Steps for Dynamic Configuration

① Create or edit listener.ora (optional).

$ vi $ORACLE_HOME/network/admin/listener.ora

② Start or restart the listener.

$ lsnrctl stop
$ lsnrctl start

Alternatively, reload to apply changes:

$ lsnrctl reload

③ Start the database.

SQL> startup

Verifying Dynamic Configuration

Use the following command to check services registered with the listener:

$ lsnrctl status

Successful dynamic registration will display the following:

Services Summary...
Service "ORCL" has 1 instance(s).
  Instance "ORCL", status READY, has 1 handler(s) for this service...

The READY status indicates that the dynamically registered instance is operational.

Command execution example

[oracle@orcl19c ~]$ lsnrctl start

LSNRCTL for Linux: Version 19.0.0.0.0 - Production on 05-AUG-2025 00:00:00

Copyright (c) 1991, 2019, Oracle.  All rights reserved.

Starting /u01/app/oracle/product/19.0.0/dbhome_1/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 19.0.0.0.0 - Production
Log messages written to /u01/app/oracle/diag/tnslsnr/orcl19c/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=orcl19c)(PORT=1521)))

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 19.0.0.0.0 - Production
Start Date                05-AUG-2025 00:00:00
Uptime                    0 days 0 hr. 0 min. 0 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Log File         /u01/app/oracle/diag/tnslsnr/orcl19c/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=orcl19c)(PORT=1521)))
The listener supports no services  ★Service not registered
The command completed successfully
[oracle@orcl19c ~]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Tue Aug 5 00:05:02 2025
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup  ★Launch a DB instance
ORACLE instance started.

Total System Global Area 1543500144 bytes
Fixed Size                  8896880 bytes
Variable Size             889192448 bytes
Database Buffers          637534208 bytes
Redo Buffers                7876608 bytes
Database mounted.
Database opened.
SQL> exit
Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.3.0.0.0
[oracle@orcl19c ~]$ lsnrctl status

LSNRCTL for Linux: Version 19.0.0.0.0 - Production on 05-AUG-2025 00:12:38

Copyright (c) 1991, 2019, Oracle.  All rights reserved.

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 19.0.0.0.0 - Production
Start Date                05-AUG-2025 00:00:00
Uptime                    0 days 0 hr. 12 min. 38 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Log File         /u01/app/oracle/diag/tnslsnr/orcl19c/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=orcl19c)(PORT=1521)))
Services Summary...
Service "orcl" has 1 instance(s).
  Instance "orcl", status READY, has 1 handler(s) for this service...  ★registered
Service "orclXDB" has 1 instance(s).
  Instance "orcl", status READY, has 1 handler(s) for this service...
The command completed successfully
[oracle@orcl19c ~]$

Points to Note for Dynamic Configuration

Ensure the listener is started before the Oracle instance.
If dynamic registration does not work, recheck the instance configuration.

Causes and Solutions for Dynamic Registration Failure

Oracle instance is not running.
- Solution: Verify that the instance is running (e.g., using ps -ef | grep pmon).
Initialization parameter LOCAL_LISTENER is incorrectly set.
- Solution: Check and correct the LOCAL_LISTENER parameter to point to the correct listener information.
Listener is not properly running.
- Solution: Check the listener’s status with lsnrctl status and restart if stopped.
Network issues preventing Oracle instance from connecting to the listener.
- Solution: Check firewall and network configurations to ensure connectivity.

Differences Between Static and Dynamic Configuration

Configuration	Accept Connections When Database is Stopped	Service Registration Method	Use Case
Static	Yes	Manually edit listener.ora	Remote startup, etc.
Dynamic	No	Automatic at database startup	Regular operations

Summary

Utilizing dynamic listener configuration simplifies daily operations and allows for efficient management of service additions or changes. Understanding the features of dynamic configuration will greatly assist in routine database management.

[reference]
4.1.1 Oracle Net Listener Configuration