DB2 ODBC inconsistent connectivity My ASP.net application uses ODBC(64 bit) to connect to DB2 Database(9.5.3). I am using 64 bit IBM DB2 Client 10.5. on Windows Server 2008 R2. Connection pool is turned on.

It works fine(immediate connectivity) for most of the time, but occasionally too much time is consumed to establish connectivity. By too much time I mean to say 10 to 11 minutes. No error is reported. No issue with database, as it can be accessed from other servers at same timestamp.

All database request issued during this time via DB2 Client are kept on hold and then once connectivity is established, all are executed immediately.

When the issue is going on, I tried to connect to database through Windows server CMD and that too waits for around 10 mins. No error is reported. Network team says they dont see network traffic from Windows server to Database server when issue is going on. And no errors from network side. Which means DB2 client is not making connectivity request.

What could be causing delay in connectivity? This is not a consistent issue. It automatically resolves after around 10 mins. Is there any issue with DB2 driver ? Was any resource withheld during that time? I am closing all connections properly.
I can't give you a definitive answer, but I would suspect slow authentication, both client and server being Windows-based: because of the client-server version mismatch there may be some extra authentication back-and-forth between them, and at some point either (or both) will traverse the Active Directory on the domain and possibly all trusted domains for user ID and group lookup.

Try setting the authentication method on the client to match that on the database server (SERVER would be the default), this might speed things up. For this you'll need to uncatalog and re-catalog the database in question.

Ask your sysadmins to check AD status if (when) you experience this issue again, may be there's a spike in load or some other issue.