Your company， Contoso， Ltd.， has a main office and a branch office. The offices are connected  by a WAN link. Contoso has an Active Directory forest that contains a single domain named  ad.contoso.com.    
The ad.contoso.com domain contains one domain controller named DC1 that is located in the  main office. DC1 is configured as a DNS server for the ad.contoso.com DNS zone. This zone is  configured as a standard primary zone.  
You install a new domain controller named DC2 in the branch office. You install DNS on DC2.  You need to ensure that the DNS service can update records and resolve DNS queries in the  event that a WAN link fails.    
What should you do（）

Your network contains a server that runs Windows Server 2008 R2. The server is configured as  an enterprise root certification authority （CA）.    
You have a Web site that uses x.509 certificates for authentication. The Web site is configured to  use a many-to-one mapping.  
You revoke a certificate issued to an external partner. You need to prevent the external partner  from accessing the Web site.    
What should you do（）