Your network contains an Active Directory domain named contoso.com. The domain contains two
domain controllers named DC1 and DC2. You install Windows Server 2012 on a new computer
named DC3. You need to manually configure DC3 as a domain controller. Which tool should you use?
A.
Server Manager
B.
winrm.exe
C.
Active Directory Domains and Trusts
D.
dcpromo.exe
Why not dcpromo
DCPromo was deprecated with the release of Server 2012. So in this cause you would use Server Manager to do the config.
dcpromo is no longer available in Server 2012. You can use Server Manager to install the Active Directory Domain Services role, then promote the server to a domain controller (also through Server Manager).
https://blogs.technet.microsoft.com/canitpro/2013/05/05/step-by-step-adding-a-windows-server-2012-domain-controller-to-an-existing-windows-server-2003-network/
It is available, just deprecated.