Synchronize time with external NTP server on Windows Server 2008 R2 / 2012 R2

Check the time difference between the server and the external NTP source:
w32tm /stripchart /computer:pool.ntp.org
 
Start CMD.EXE with Administrative permissions, and run the following:

net stop w32time
w32tm /config /syncfromflags:manual /manualpeerlist:"pool.ntp.org"
w32tm /config /reliable:yes
net start w32time