The root domain of the Adatum forest is Adatum.local. The contoso.com domain tree is part of the Adatum forest.
Don has an account in the australia.contoso.com domain and is signing on to a computer that is a member of the computers.adatum.local domain. No additional UPNs have been configured.
Which UPN suffix will Don use to sign on to this computer?
A. @adatum.com
B. @adatum.local
C. @computers.adatum.local
D. @australia.contoso.com
only domain controllers of australia.contoso.com can authenticate DON , so in my point of view, D is the correct answer