Your company has a single Active Directory forest that has six domains. All DNS servers in the forest run Windows Server 2008. You need to ensure that all public DNS quieries are channeled through a singlecahing- only DNS server. Which two actions should you perform?() 
A、A.Disable the root hints
B、B.Enable BIND secondaries
C、C.Configure a forwarder to the caching DNS server
D、D.Configure a GlobalNames host (A) record for the hostname of the caching DNS server