From server manager, go to Features, then add
Expand:
- Remote Server Administration Tools
- Role Administration Tools
- Active Directory Domain Services Tools
and then check Active Directory Domain Controller Tools
it includes:
- Active Directory Users and Computers
- Active Directory Domains and Trusts
- Active Directory Sites and Services
- ...
Server 2008 R2 Instructions:
Under Role Administration Tools, expand
- AD DS and AD LDS Tools
- AD DS Tools
- AD DS Snap-Ins and Command-Line Tools.
