Your company has a single Active Directory domain. All domain controllers run Windows
Server 2003.
You install Windows Server 2008 R2 on a server.
You need to add the new server as a domain controller in your domain.
What should you do first?

A.
On a domain controller run adprep /rodcprep.

B.
On the new server, run dcpromo /adv.

C.
On the new server, run dcpromo /createdcaccount.

D.
On a domain controller, run adprep /forestprep.

Explanation:
http://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/9931e32f-6302-40f0-
a7a1-2598a96cd0c1/
DC promotion and adprep/forestprep
Q: I’ve tried to dcpromo a new Windows 2008 server installation to be a Domain Controller,
running in an existing domain. I am informed that, first, I must run adprep/forestprep (“To
install a domain controller into this Active Directory forest, you must first perpare the forest
using “adprep/forestprep”. The Adprep utility is available on the Windows Server 2008
installation media in the Windows\sources\adprep folder”

A1)
You can run adprep from an existing Windows Server 2003 domain controller. Copy the
contents of the \sources\adprep folder from the Windows Server 2008 installation DVD to the
schema master role holder and run Adprep from there.
A2) to introduce the first W2K8 DC within an AD forest….
(1) no AD forest exists yet:
–> on the stand alone server execute: DCPROMO
–> and provide the information needed
(2) an W2K or W2K3 AD forest already exists:
–> ADPREP /Forestprep on the w2k/w2k3 schema master (both w2k/w2k3 forests)
–> ADPREP /rodcprep on the w2k3 domain master (only w2k3 forests)
–> ADPREP /domainprep on the w2k3 infrastructure master (only w2k3 domains)
–> ADPREP /domainprep /gpprep on the w2k infrastructure master (only w2k domains)
–> on the stand alone server execute: DCPROMO
–> and provide the information needed