You have four dcs in your domain. active directory appears to be corrupted on one of the dcs, and you suspect a failing hard drive. you attempt to remove it from the domain, but the procedure fails. you take the dc offline permanently and will replace it with another dc of the same name. what must you do before you can replace the dc?

perform a metadata cleanup

Explanation:

Based on the information provided within the question it can be said that in this situation the the first thing you must do is perform a metadata cleanup. This is a procedure that must be used every time when forcibly taking a DC offline, this will remove all data from the Active Directory Domain Services that identifies a DC to the replication system. Allowing you to replace it with another DC of the same name.