pool.ntp.org

[Andreas Simon]

On Wednesday 06 October 2004 19:17, Darren Critchley wrote:

> Odd, I am a developer on the Ipcop firewall project, and we use crontab
> to call ntpdate at set intervals with no issues or clock jumping.

Probably because your hw clock is sufficently exact and the jumps when ntpdate 
sets the clock are too small for you to care or notice.

There is a verbose explanation in ntpd's documentation how ntpd works and why.

"ntpd adjusts the clock in small steps so that the timescale is effectively 
continuous and without discontinuities."

and

"As the result of this behavior, once the clock has been set, it very rarely 
strays more than 128 ms, even under extreme cases of network path congestion 
and jitter."

and 

"In scenarios where a considerable amount of data are to be downloaded or 
uploaded over telephone modems, timekeeping quality can be seriously 
degraded. ... huff-n'-puff filter is designed to correct the apparent time 
offset in these cases."

ntpdate doesn't do all these things and as a result is less exact.

ntpd does by far a better job at syncronizing time then ntpdate does. But that 
doesn't mean that ntpdate isn't good enough for most people.

Cheers,
Andreas