On Microsoft Servers, a domain controller (DC) is a server computer[1][2] that responds to security authentication requests (logging in, etc.) within a Windows domain.[3][4] A domain is a concept introduced in Windows NT whereby a user may be granted access to a number of computer resources with the use of a single username and password combination.
^"Domain Controller Roles". Microsoft TechNet or A domain controller (DC) is a server that responds to security authentication requests within a Windows Server domain. It is a server on a Microsoft Windows or Windows NT network that is responsible for allowing host access to Windows domain resources. A domain controller is the centerpiece of the Windows Active Directory service. It authenticates users, stores user account information and enforces security policy for a Windows domain. Retrieved Dec 4, 2009.
^"Domain Controller Roles". Windows Server 2003 Technical Reference. Microsoft TechNet. 2010-06-03. Retrieved 2012-11-21. A domain controller is a server that is running a version of the Windows Server® operating system and has Active Directory® Domain Services installed.