Verifying the Oracle listener configuration
The listener is a process that listens for client connection requests. It receives incoming client connection requests and manages the traffic of these requests to the database. Before connecting to a target database or repository database instance, you can use the STATUS command to verify the listener configuration.
The STATUS command displays basic status information about a specific listener, including a summary of listener configuration settings, listening protocol addresses, and a summary of services registered with that listener.
Enter the following command at the command prompt: 'lsnrctl STATUS'
The default value assigned to the listener port is 1521.