Your network contains an Active Directory domain named contoso.com. The domain contains a  domain controller named DC1. DC1 hosts a standard primary zone for contoso.com.     You discover that non-domain member computers register records in the contoso.com zone. You  need to prevent the non-domain member computers from registering records in the contoso.com  zone. All domain member computers must be allowed to register records in the contoso.com  zone.     What should you do first（）

• A、Configure a trust anchor.
• B、Run the Security Configuration Wizard （SCW）.
• C、Change the contoso.com zone to an Active Directory-integrated zone.
• D、Modify the security settings of the %SystemRoot%/System32/Dns folder.