Can I create the active directory forest corp.domain.com without creating domain.com first?

Is there any way which I can create the active directory domain corp.domain.com without first creating domain.com AD DCs?

Or to put another way, can corp.domain.com be the root of the forest?

Solution 1:

The FQDN of the forest root domain can be any valid FQDN, given that its length does not exceed 65 characters and otherwise conforms to the conventions and limitations described in KB909264

So yes, it most certainly can - just don't use the .local-tld.

As noted in the comments, using an otherwise unused 3rd-level domain as the root of your AD DNS namespace is actually recommended, as you might otherwise end up with a naming collision when you want to use the 2nd-level name in public DNS and already have it in use internally.