问题：

[单选]

Your company has a single Active Directory directory service forest with a forest root domain and a child domain. The child domain is set to the default domain functional level. You install a second domain controller in the child domain by promoting a server named SVR1. You need to rename SVR1 to DC2， and you must ensure that there will be no interruption in the ability of client computers to authenticate to DC2， except during reboot. 
What should you do？（） 

A .  Raise the domain functional level of the child domain to Windows 2000 native. Use System Properties on SVR1 to rename SVR1 to DC2.
B .  Raise the domain functional level of the child domain to Windows Server 2003. Run the netdom command to rename SVR1 to DC2.
C .  Raise the domain functional level of the child domain to Windows 2000 native. Run the dcpromo command on SVR1 to remove Active Directory directory service. Use System Properties to rename SVR1 to DC2. Run the dcpromo command to re-install Active Directory.
D .  Raise the domain functional level of the child domain to Windows Server 2003. Create a DNS CNAME record for DC2.contoso.com that points to SVR1.contoso.com.