how to configure ntp server in windows server 2012 r2?
Select [Administrative template] - [System] - [Windows Time Service] [Time Providers] on the left Pane, and Open [Enable Windows NTP Server] on the right Pane. Check a box [Enabled] which is upper-left like follows. Back to [Windows Time Service] on the left Pane, and click to Open [Globa Configuration Settings].