You need to prepare a domain controller for cloning

Your network contains an Active Directory domain named contoso.com. All domain
controllers run Windows Server 2012 R2.
On all of the domain controllers, Windows is installed in C:\Windows and the Active Directory
database is located in D:\Windows\NTDS\.
All of the domain controllers have a third-party application installed.
The operating system fails to recognize that the application is compatible with domain
controller cloning.
You verify with the application vendor that the application supports domain controller cloning.
You need to prepare a domain controller for cloning.
What should you do?

A.
In D:\Windows\NTDS\, create an XML file named DCCloneConfig.xml and add the
application information to the file.

B.
In the root of a USB flash drive, add the application information to an XML file named
DefaultDCCIoneAllowList.xml.

C.
In D:\Windows\NTDS\, create an XML file named CustomDCCloneAllowList.xml and add
the application information to the file.

D.
In C:\Windows\System32\Sysprep\Actionfiles\, add the application information to an XML
file named Respecialize.xml.

Explanation:
Place the CustomDCCloneAllowList.xml file in the same folder as the Active Directory
database (ntds. dit) on the source Domain Controller.

http://blogs.dirteam.com/blogs/sanderberkouwer/archive/2012/09/10/new-features-inactive-directory-domain-services-in-windows-server-2012-part-13-domain-controller-cloning.aspx
http://www.thomasmaurer.ch/2012/08/windows-server-2012-hyper-v-how-to-clone-avirtual-domain-controller
http://technet.microsoft.com/en-us/library/hh831734.aspx