Manually, you could run these commands:
net time /setsntp:(domaincontrollersname)
net time /set
However, by default, your root dc is automatically assigned as the ntp serber for the domain and all clients should set their time on logon. The DC should be setup to get its time from something like time.microsoft.com, if I remember right.
You can query a time server by typing “net time /querysntp.”