This is purely hypothetical, thankfully I'm not actually in this situation right now but I'm wondering how you would deal with it if it ever did come up.
Lets say I've got a small network of (~20-30 users) and they have four physical servers:
2x Domain controllers
1x File Server
1x Exchange Server
All four of these servers are running Server 2012 R2, and each one has a 2TB external hard disk attached that is using the built-in Windows Server Backup to make nightly backups which are running successfully.
Now, the worst happens - a sysadmin deletes something critical out of Active Directory Users and Computers, seriously screwing up the network. Lets say they "accidentally" deleted an entire OU.
How do you recover from this situation, given that you have two domain controllers and something fairly sophisticated like Exchange Server that heavily relies on Active Directory?
Can you just restore one of the domain controller's to yesterday's backup? Or will the second DC immediately replicate it's changes over and clobber it if you do? Must you restore BOTH DCs simultaneously? Would restoring cause major problems with Exchange?
What are the steps you would go through to get the lost OU back?