Configuring NTP on Server 2012 R2

This is the command to use if you want your Server 2012 R2 to synchronize its time against a time server:

w32tm /config /,0x8 /syncfromflags:MANUAL
net stop w32time
net start w32time is good to use because it is a round-robin of random selected NTP servers.

If your server is a VM inside a Hyper-V, remember to disable time sync on the virtual mashine in Hyper-V manager.

Other useful commands:

w32tm /query /configuration gives you the configuration
w32tm /query /status gives you information
w32tm /resync Use it on a client to force a resync of the time

If you want to start from scratch you can reset everything by running this command:

net stop w32time
w32tm /unregister
w32tm /register

Remember to create a rule in your firewall that allows udp/123. That is the NTP protocol.