Fortigate can be configured as NTP server. This is applicable with FortiOS 5.0 and 5.2 as well.
CLI configuration syntax-
config system ntp
set ntpsyn enable
set server-mode enable
set interface <interface_list>
end
Regards,
Deepak G N R
In case you'd like to do this from the GUI:
Go to System > Dashboard > Status and in the System Information Widget click the [Change] next to the System Time
Check the Enable NTP Server box and add the interfaces you'd like to serve as NTP Server