132. The tnsnames.ora file has an entry for the service alias ORCL as follows:
ORCL =
( DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.156.24.216)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl.oracle.com)
)
)
The TNSPING command executes successfully when tested with ORCL, but 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 environmental variable is set to a wrong value.
C.The orcl.oracle.com database service is not registered with the listener.
D.The DEFAULT_DOMAIN parameter is set to a wrong value in the sqlnet.ora file.
Answer: C
答案解析：
当 SERVICE_NAME 填写不正确时，你可以 tnsping 通数据库实例，但是却无法连接到数据库实例，因为你填写错
的 SERVICE_NAME 并没有注册到 LISTENER 当中。
listener 是在 db server 上配置，凡是在 client 端要连接 db 都需要通过 listener。