Active Directory Domain Services (AD DS) stores directory data and manages communication between users and domains, including user logon processes, authentication, and directory searches. An Active Directory domain controller is a server that is running AD DS.
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What's New in AD DS in Windows Server 2012 AD DS in Windows Server 2012 includes new features that make it simpler and faster to deploy domain controllers (both on-premises and in the cloud), and easier to perform administrative tasks at scale.