April 9, 1999 - the first production active directory domain
On April 9, 1999 the Domain Controllers for the redmond.corp.microsoft.com Windows NT4-based domain were upgraded to a pre-release version of Windows 2000 Server and thus became the world’s first production Active Directory domain:
![](https://kbin.social/media/cache/resolve/entry_thumb/28/fe/28fe3f41e17b6ac7f1f0f7345de39c1a9ee7999249789a7b3719e53b5d137582.jpg)