The tnsnames.ora file has an entry for the service alias ORCL as follows:
The TNS ping command executes successfully when tested with ORCL; however, from the same OS user
session, you are not able to connect to the database instance with the following command:
SQL > CONNECT scott/tiger@orcl
What could be the reason for this?
A.
The listener is not running on the database node.
B.
The TNS_ADMIN environment variable is set to the wrong value.
C.
The orcl.oracle.com database service is not registered with the listener.
D.
The DEFAULT_DOMAIN parameter is set to the wrong value in the sqlnet.ora file.
E.
The listener is running on a different port.
Explanation:
Service registration enables the listener to determine whether a database service and its service handlers are
available. A service handler is a dedicated server process or dispatcher that acts as a connection point to a
database. During registration, the LREG process provides the listener with the instance name, database
service names, and the type and addresses of service handlers. This information enables the listener to start a
service handler when a client request arrives.