Resolving the TNS-12502 error

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)
    )
  )

For More Information

• Dozens more answers to tough Oracle questions from Karen Morton are available.
• The Best Oracle Web Links: tips, tutorials, scripts, and more.
• Have an Oracle or SQL tip to offer your fellow DBAs and developers? The best tips submitted will receive a cool prize. Submit your tip today!
• Ask your technical Oracle and SQL questions -- or help out your peers by answering them -- in our live discussion forums.
• Ask the Experts yourself: Our SQL, database design, Oracle, SQL Server, DB2, metadata, object-oriented and data warehousing gurus are waiting to answer your toughest questions.