Resolving the TNS-12502 error

I have an Oracle database with a server IP of 1.1.1.10, and it also has a virtual IP of 10.10.10.10. The virtual...

IP is the way some of my clients must hit the database with the use of tnsnames.ora(host=10.10.10.10) instead of the actual IP address. Those clients are receiving 12502 errors and the listener log is showing these errors also. Is there anything special I need to do?

Here's what the Error Messages guide says about the TNS-12502 error:

TNS-12502 TNS:listener received no CONNECT_DATA from client
Cause: No CONNECT_DATA was passed to the listener.
Action: Check that the service name resolved from TNSNAMES.ORA has the CONNECT_DATA component of the connect descriptor.

So, the first step is to check your TNSNAMES.ORA file that the clients are using and verify that it looks something like this:

ORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.10.10.10)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = ORCL)
    )
  )

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