Your company has a main office and four branch offices. The main office is located in London.
The network contains an Active Directory domain named contoso.com. Each office contains one domain controller that runs Windows Server 2012. The Active
Directory site topology is configured as shown in the exhibit. (Click the Exhibit button.)
You discover that when a domain controller in a branch office is offline for maintenance, users in that branch office are authenticated by using the domain controllers
in any of the sites. You need to recommend changes to Active Directory to ensure that when a domain controller in a branch office is offline, the users in that branch
office are authenticated by the domain controllers in London.
What should you include in the recommendation?
Exhibit

A.
Modify the DC Locator DNS Records settings.

B.
Disable site link bridging.

C.
Modify the site link costs.

D.
Modify the service location (SRV) records in DNS.

Explanation:
If local DC (domain controller) is not available, DC Locator service will look for another DC in a different site.