Just a quick write up for my own convenience. Large organizations tend to have a lot of everything, from buildings and employees to Domain Controllers.
In times were Domain Controllers undergo maintenance, like an upgrade or relocation, dependent services may be impacted.
The way identity sources are configured differs per product, fortunately less often hard-coded by specifying a single domain controller, usually more flexible by specifying the AD domain.
For a vCenter Server Appliance (vCSA), additional identity sources can be configured, one commonly used is the Active Directory (Integrated Windows Authentication).
BTW, As a prerequisite, the vCSA should be joined to the Windows domain.