Server certificate FQDN in case of alias routing

We have a PI messaging server at XXXX.J2EEPORT.COM. We recently added an F5 load balancer in front of it and because of that, the alias of PI has changed to YYYY.J2EEPORT.COM, the messaging server however remains at the same XXXX host.

We are configuring the server certificate in PI SSL configuration for SSL access points. What should be the FQDN that we should use ? Should that be the PI messaging server FQDN i.e. XXXX.J2EEPORT.COM or the actual DNS i.e. the alias YYYY.J2EEPORT.COM which lies on the F5

Thanks,