https://wadhahdaouehi.tn/2019/05/set-up-dns-for-rac-on-oracle-linux-7/

https://saneshdba.blogspot.com/p/srvctl-commands-in-oracle-rac-srvctl.html

After upgrade to 12c, check if sqlnet.ora has below information SQLNET.ALLOWED_LOGON_VERSION_SERVER = 11 SQLNET.ALLOWED_LOGON_VERSION_CLIENT =…