VS IP is working perfectly but Getting problem when using name in DNS.

I am load balancing siebel webserver. There is Oracle Identity manager installed over webserver working with OAM. Everything was working fine When we were using VS ip. Now we have resolved the VS ip against a name in DNS. Even then it was working perfectly except for the logout that IDM was redirecting to VS IP instead of name which was resolved in DNS. Once they changed the logout entry in IDM now we are unable to see the login page at all. But still everything is working with VS IP. Please any suggestions.