What is the most "efficient" and "secure" way to keep the clocks of 
servers on a network in sync?

Because OpenNTPD was designed with security in mind from the start, I 
was thinking about using ntpd only on all systems. One system would get 
time from the NTP pool and all other servers on the network would sync 
to the local server. Is this the best way?

Then I discovered timed. Does anybody use it? Is it as secure? What are 
the (dis)advantages/differences compared to ntpd?

I was was reading timed(8) and it states the following:

"One way to synchronize a group of machines is to use an NTP daemon to 
synchronize the clock of one machine to a distant standard or a radio 
receiver and -F hostname to tell its timed daemon to trust only itself."

I assume that all the other machines on the network would run timed only?

How do you guys keep your clocks in-sync?

-pachl