Your network contains an Active Directory forest. The forest contains two Active Directory domains named adatum.com and corp.adatum.com. The forest functional level is Windows Server 2008. The functional level of both domains is Windows Server 2008.
The forest contains three domain controllers. The domain controllers are configured as shown in the following table.
DC1 and DC2 have the DNS Server server role installed and are authoritative for both adatum.com and corp.adatum.com.
In the corp.adatum.com domain, you install a new server named RODC1.corp.adatum.com that runs Windows Server 2012. You plan to configure RODC1.corp.adatum.com as a read-only domain controller (RODC).
You run the adprep.exe /rodcprep command on DC3 and receive the following error message:
You need to identify what prevents you from successfully running Adprep /rodcprep on DC3.
What should you identify?
A. The domain functional level of corp.adatum.com is set to the wrong level.
B. DC3 cannot connect to the infrastructure master on DC1.
C. DC3 cannot connect to the PDC Emulator on DC2.
D. The forest functional level is set to the wrong level.
Explanation:
https://support.microsoft.com/en-us/help/949257/error-message-when-you-run-the-adprep-rodcprep-command-in-windows-server-2008-adprep-could-not-contact-a-replica-for-partition-dc-domaindnszones,dc-contoso,dc-com