Your network consists of a single Active Directory domain.
All domain controllers run Windows Server 2003.
You upgrade all domain controllers to Windows Server 2008 R2.
You need to ensure that the Sysvol share replicates by using DFS Replication (DFS-R).
What should you do?

A.
From the command prompt, run dfsutil /addroot:sysvol.

B.
From the command prompt, run netdom /reset.

C.
From the command prompt, run dcpromo /unattend:unattendfile.xml.

D.
Raise the functional level of the domain to Windows Server 2008 R2.

Explanation:
http://technet.microsoft.com/en-us/library/cc794837%28v=ws.10%29.aspx
Introduction to Administering DFS-Replicated SYSVOL
SYSVOL is a collection of folders that contain a copy of the domain’s public files, including system policies,
logon scripts, and important elements of Group Policy objects (GPOs). The SYSVOL directory must be present
and the appropriate subdirectories must be shared on a server before the server can advertise itself on the
network as a domain controller. Shared subdirectories in the SYSVOL tree are replicated to every domain
controller in the domain.
Note:
For Group Policy, only the Group Policy template (GPT) is replicated through SYSVOL replication. The
Group Policy container (GPC), which is stored in the domain, is replicated through Active Directory
replication. For Group Policy to be effective, bothparts must be available on a domain controller.
..
Using DFS Replication for replicating SYSVOL in Windows Server 2008
Distributed File System (DFS) Replication is a replication service that is available for replicating
SYSVOL to all domain controllers in domains that have the Windows Server 2008 domain functional
level.DFS Replication was introduced in Windows Server 2003 R2. However, on domain controllers that are
running Windows Server 2003 R2, SYSVOL replication is performed by the File Replication Service (FRS).