AD, AD domains, and primary domain controllers: The backbone of enterprise identity-and why DNS keeps it alive
At some point, every enterprise faces the same quiet operational nightmare: hundreds of users, thousands of devices, multiple locations, and someone in the IT department manually managing who gets access to what. Active Directory (AD) was Microsoft's answer to that problem when it shipped with Windows 2000, and it remains, over two decades later, the dominant identity and access infrastructure in enterprise networks worldwide.