Your network consists of a single Active Directory domain. All domain controllers run Windows Server 2008 R2 and are configured as DNS servers. A domain controller named DC1 has a standard primary zone for contoso.com. A domain controller named DC2 has a standard secondary zone for contoso.com. You need to ensure that the replication of the contoso.com zone is encrypted. You must not lose any zone data. What should you do（）

A. On both servers， modify the interface that the DNS server listens on.
B. Convert the primary zone into an Active Directory-integrated zone. Delete the secondary zone.
Convert the primary zone into an Active Directory-integrated stub zone. Delete the secondary zone.
D. Configure the zone transfer settings of the standard primary zone. Modify the Master Servers lists on the secondary