Can all NTP Traffic Going to External Servers be Redirected to an Internal Time Server?
Currently there is no way to redirect traffic bound for all external NTP servers to a single internal server. However, traffic destined to specific external servers can be translated to the address of an internal server using NAT policies. If the server exists on a different zone than that of the hosts that will be accessing it, a simple destination NAT will suffice. However, if the server is on the same network (zone) as the hosts, a "U-Turn" NAT is needed, as shown here:
In this example "Public NTP Server" is an address object that contains the IP address of a single public NTP server. The "Private NTP Server" is an address object that contains the address of the private NTP server where traffic should be sent.