Your network contains one Active Directory domain named contoso.com. The domain contains 10
domain controllers and a read-only domain controller (RODC) named RODC01.
You need to ensure that when administrators create users in contoso.com, the default user principal
name (UPN) suffix is litwareinc.com.
Which cmdlet should you use?

A.
the ntdsutil command

B.
the Set-ADDomain cmdlet

C.
the Install-ADDSDomain cmdlet

D.
the dsadd command

E.
the dsamain command

F.
the dsmgmt command

G.
the net user command

H.
the Set-ADForest cmdlet

Explanation:
The following example demonstrates how to create a new UPN suffix for the users in the
Fabrikam.com forest:
Set-ADForest -UPNSuffixes @{Add=”headquarters.fabrikam.com”}
Creating a UPN Suffix for a Forest
https://technet.microsoft.com/sv-se/library/Dd391925(v=WS.10).aspx