Your company has a single active directory forest that has an active directory domain named na.contoso.com. a member server named server2 runs the DNS server role. The server2 DNS service hosts multiple secondary zones including na.contoso.com. you need to reconfigure server2 as a caching-only DNS server. What should you do?（）

• A、Uninstall and reinstall the DNS service on server2.
• B、Change all the DNS zones on server2 to stub zones.
• C、Disable and then enable the DNS service on server2.
• D、Delete the na.contoso.com DNS zone domain from server2. Restart the DNS service on server2.