Window clients time is not updating in active directory domain
This is great when a user is authenticating directly against a domain controller but not so good when a user, especially a remote user, is logging onto a machine or a VPN connection using Windows cached credentials.
Cached credentials allow a user to access machine resources when a domain controller is unavailable.
Microsoft has a pretty detailed KB Article on this topic which even includes a very handy "Fixit for me" utility, however that tool doesn't run on Windows Server 2012 for some reason, so let me just cut right to chase on how to quickly configure your domain to sync with an external NTP time server.
Copy the text below into a file and double click it.
Side note: The Clients and other Member Servers are already using NTP, but their source will be your domain controller, not an internet time server.