Explanation:
Box 1: DC2
You create IFM by using Windows Azure Backup on DC2.
Box 1: Ntdsutil.exe
Windows Server 2008 and Windows Server 2008 R2 include an improved version of the Ntdsutil tool that you can use to create installation media for an additional domain controller. You can use Ntdsutil.exe to create installation media for additional domain controllers that you are creating in a domain. The IFM method uses the data in the installation media to install AD DS, which eliminates the need to replicate every object from a partner domain controller.
https://social.technet.microsoft.com/wiki/contents/articles/8630.active-directory-step-by-step- guide-to-install-an-additional-domain-controller-using-ifm.aspx
https://www.windowstechno.com/deploy-domain-controller-using-install-from-media-ifm/