Your infrastructure divided in 2 sites. You have a forest root domain and child domain. There is only
one DC on site 2 with no FSMO roles. The link goes down to site 2 and no users can log on. What
FSMO roles you need on to restore the access?

A.
Infrastructure master

B.
RID master

C.
Domain Naming master

D.
PDC Emulator

Explanation:
D)
The PDC emulator is used as a reference DC to double-check incorrect passwords and it also
receives new password changes.
PDC Emulator is the most complicated and least understood role, for it runs a diverse range of
critical tasks. It is a domain-specific role, so exists in the forest root domain and every child domain.
Password changes and account lockouts are immediately processed at the PDC Emulator for a
domain, to ensure such changes do not prevent a user logging on as a result of multi-master
replication delays, such as across Active Directory sites.