A.ConfiguretheinternalDNSservertohavearootzone.
B.ConfiguretheDallasDNSservertousethedefaultroothints.
C.ConfiguretheDallasDNSservertoforwardallrequestfortheexternalnamespacetotheexternalDNSserver.
D.Createacaching-onlyDNSserverontheperimeternetwork.
E.CreateastubzonefortheexternalnamespaceontheDallasDNSserver.
参考答案：BCE
