Your network consists of a single Active Directory domain. You have a domain controller and a   member server that run Windows Server 2008 R2. Both servers are configured as DNS servers. Client  computers run either Windows XP Service Pack 3 or Windows 7.   You have a standard primary zone on the domain controller. The member server hosts a secondary copy  of the zone.You need to ensure that only authenticated users are allowed to update host （A） records in the DNS zone.   What should you do first（）

• A、On the member server， add a conditional forwarder.
• B、On the member server， install Active Directory Domain Services.
• C、Add all computer accounts to the DNSUpdateProxy group.
• D、Convert the standard primary zone to an Active Directory-integrated zone.