Your network contains an Active Directory forest. The forest contains one domain. The
domain contains two domain controllers named DC1 and DC2 that run Windows Server
2008 R2.
DC1 was installed before DC2.
DC1 fails.
You need to ensure that you can add 1,000 new user accounts to the domain.
What should you do?

A.
Modify the permissions of the DC2 computer account.

B.
Seize the schema master FSMO role.

C.
Configure DC2 as a global catalog server.

D.
Seize the RID master FSMO role.

Explanation:

MS Press – Self-Paced Training Kit (Exam 70-640) (2nd Edition, July 2012) pages 536-537
RID master failure
A failed RID master eventually prevents domain controllers from creating new SIDs and,
therefore, prevents you from creating new accounts for users, groups, or computers.
However, domain controllers receive a sizable pool of RIDs from the RID master, so unless
you are generating numerous new accounts, you can often go for some time without the RID
master online while it is being repaired. Seizing this role to another domain controller is a
significant action. After the RID master role has been seized, the domain controller that had
been performing the role cannot be brought back online.