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
Delete the na.contoso.com DNS zone domain from Server2. Restart the DNS service on Server2.