TNSPING response time

Question

I am connecting to a 12c database from my client machine using 12c oracle client. Below is my TNS entry.

PLMDEV1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = sesbexa3-scan2.exadata.ericsson.se)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = PLMDEV1)
      (UR = A)
    )
  )

When i am doing the TNSPING from client machine to the database, i am getting the output as below.

Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = sesbexa3-scan2.exadata.ericsson.se)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = PLMDEV1) (UR = A)))
OK (20 msec)
OK (0 msec)
OK (0 msec)
OK (10 msec)
OK (40 msec)
OK (0 msec)
OK (0 msec)
OK (0 msec)
OK (20 msec)
OK (0 msec)

Can some one explain me what is this 0ms, 10ms,20ms,40ms means? If it is the over all time taken for client to establish connection with database, why i see different response times? Will this cause any performance issues to my client (while establishing connection to the DB)?

Answer 1

Clear explanation in the docs.

... determines whether the listener for a service on an Oracle Net network can be reached successfully ... then it displays an estimate of the round trip time (in milliseconds) it takes to reach the Oracle Net service.

Arguments:

- net_service_name must exist in tnsnames.ora file or the name service in use, such as NIS.

- count determines how many times the program attempts to reach the server. This argument is optional.

No peformance issues in your posted test, but be aware:

It does not actually determine whether or not the database itself is running. Use SQL*Plus to attempt a connection to the database.

Finally:

TNSPING tests connectivity to a service / listener, not to a server, you can always try to check the listener log or restart it to check if that makes any difference.