Kerberos with APM is prompting for security login and sso login everytime.

 Okay, it was a P1 but wanted I to know what would be the issue when the Main engineers are working on this like a side track analysis. So, the issue is with the reverse lookup, We see the FQDN which is on GTM using gslbx is not working for reverse lookup and it failing to login for Kerberos. fixed after changing the dns to point directly to app server.