I have a Server 2003 SP2 Standard server that used to be a physical box. It's running Exchange 2003, Directory Services and Certificate Authority. It used to be the FSMO role holder.
Two Server 2012 servers were installed and both configured as domain controllers. One of these took over all FSMO roles.
The 2003 server was virtualized as P2V. Then, because of a snapshot rollback, the server fell into a USN Rollback state. Since that time, I have raised it's priority level so that it will be very unlikely to handle authentication requests by logon attempts. Also, I have installed a new Server 2003 virtual machine that's running Exchange 2003 and migrated the mailboxes to it. I have yet to fully decommission the old Exchange server because I'm not sure of what step to take next to gracefully decommission it. I plan on migrating to Office 365, the sooner the better.
I also want to remove the Certificate Authority and finally demote it so that it can be turned off for good.This server has been a headache since I inherited the network a year ago.
My questions are:
Do I need to fully remove Exchange before I start messing with CA?
Can I install a new Server 2012 CA or do I have to migrate the CA from 2003 to 2012?
If I can install a new Server 2012 CA without touching the CA on 2003, do I have to worry about corruption when I demote the 2003 server?