On Primary AD
w32tm /config /manualpeerlist:pool.ntp.org /syncfromflags:manual /reliable:yes /update
On Secondary DC
w32tm /config /syncfromflags:domhier /update
Then run on both server this
w32tm.exe /resync /rediscover
To check status
w32tm /query /status
To check if the source is pool.ntp.org
w32tm /query /source