As part of SSL configuration between WebLogic tier and DB tier, post sqlnet.ora settings and scan listener restart, we encountered an ORA-12545 error on a 3 node RAC database when using the SCAN listener.

We verified the LISTENER status and we could find all the services in READY status. Tried using VIP, it worked perfectly. So, the only issue was connecting through SCAN. We were fortunate to find a solution after a very quick search over the net. The MOS Doc 364855.1 explained the issue and provided the solution.

As part of the configuration, we set the LOCAL_LISTENER to an VIP hostname. After modifying the LOCAL_LISTENER string to point to VIP IP address, we could manage to connect through the SCAN.

Logically the VIP hostname should have worked, but, we noticed through many references the same issue. 



References:
Client Connection to RAC Intermittently Fails-ORA-12545 TNS: Host or Object Does not Exist (Doc ID 364855.1)
https://ardentperf.com/2007/04/02/local_listener-and-ora-12545/
http://spotdba.blogspot.com/2012/08/error-ora-12545-while-trying-to-connect.html