Can tnsping prove that the Oracle database is available?

The Listener is an Oracle server-based network service that listens to client connection requests to the database server side. Oracle officially defines it as:A process, listens for incoming client connection requests and manages network traffic to the Datab Ase.?
? The local service name is one of the Oracle client network configurations, plus the Oracle name server (Oracle Names server).

?? The client can interact with the database server by listening, if we test with tnsping and return to normal, does that mean that the database is available? The answer is in the negative.

1. The following monitoring is normal boot:

? ?

2. Close the database at this time:

3. Execute the tnsping from the client, the display is connected properly.

As we can see, tnsping just verifies that the path between the client and the database server's listening port is good, but does not mean that the database service is available because the client and Oracle server interactions are performed through the Oracle Server server process. The private memory space is the PGA, so sometimes we do operations detection, tnsping cannot represent the Oracle database available, you can use Sqlplus to actually execute a statement (select Sysdate from dual).

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Can tnsping prove that the Oracle database is available?