On Tue, Apr 22, 2008 at 5:07 AM, Simon Jolle <urandomdev at gmail.com> wrote: > The problem is that other hosts are able to synchronize the time from > our servers. How to disable that? Which other hosts? Other hosts in the same subnet as dns1 and dns2? If that is the problem, maybe you should try changing "mask 255.255.255.0" to "mask 255.255.255.255". The "mask 255.255.255.0" means all the class C subnet. HTH, Filipe