Your network contains an Active Directory forest named contoso.com.
The forest contains two domains named contoso.com and child.contoso.com and two sites named Site1 and Site2. The domains and the sites are configured as
shown in following table.

When the link between Site1 and Site2 fails, users fail to log on to Site2.
You need to identify what prevents the users in Site2 from logging on to the child.contoso.com domain.
What should you identify?

A.
The placement of the global catalog server

B.
The placement of the infrastructure master

C.
The placement of the domain naming master

D.
The placement of the PDC emulator

Explanation:
The exhibit shows that Site2 does not have a PDC emulator. This is important because of the close interaction between the RID operations master role and the
PDC emulator role
The PDC emulator processes password changes from earlier-version clients and other domain controllers on a best-effort basis; handles password authentication
requests involving passwords that have recently changed and not yet been replicated throughout the domain; and, by default, synchronizes time. If this domain
controller cannot connect to the PDC emulator, this domain controller cannot process authentication requests, it may not be able to synchronize time, and password
updates cannot be replicated to it.