Check the OOB Server is running on the correct machine and listening on the correct port:
oobping -h myserver -t 8888 Host: myserver, Port: 8888 Attempting connection...OK Examining Server... OOB Server Version: 1.1.0.00 OOB Server Name: OOB
Note oobping defaults the port to 8888 so you can omit -t.
If you specify the wrong port and some other service is listening on it you will get a variety or errors like the one below when pointing oobping at an SMTP server on port 25.
oobping -h myserver -t 25 Host: myserver, Port: 25 Failed to receive data Packet (size=842149920) too big for buffer (size=256)
If there is nothing listening on the specified port then you will get a connection refused error and you should check the OOB Server is configured to use the port you specified and is running. For example:
oobping -h myserver -t 8889 Host: myserver, Port: 8889 Connection refused, connect(), after 5 attempts
If you have specified access control rules in the OOB Server then you might see an error such as this:
oobping -h myserver -t 8888 Host: myserver, Port: 8888 Client denied access due to access control rule.
Oracle is a registered trademark of Oracle Corporation and/or its affiliates.