Computer Configuration > Policies > Centrify Settings > Mac OS X Settings > Firewall > Enable network time
On Mac OS X Servers, enabling this policy has no effect. If the firewall is enabled, the Network Time service is not allowed through the firewall.
If the firewall is enabled, enabling this group policy is the same as clicking the On checkbox to allow communication through the firewall for Network Time. If you do not enable this group policy, traffic from the Network Time service will be blocked.
This policy can take effect dynamically at the next group policy refresh interval without rebooting the computer.