Richard B. Gilbert wrote: > [EMAIL PROTECTED] wrote: > > Richard B. Gilbert wrote: > > > >>JCA wrote: > >> > >>> I have three Linux boxes, namely, A, B, and C, in my LAN. I use C > >>>as the NTP server for my LAN. C, in turn, gets its synchronization > >>>from some external NTP server. > >>> > >>> Both A and B use the same (very simple) ntp.conf configuration file: > <snip> > > > > This is what I consider a minimal NTP.CONF: > > > > server x.x.x.x maxpoll 6 > > driftfile /etc/ntp.drift > > enable auth > > > > The "maxpoll 6" forces ntpd to update every 64 seconds. > > "enable auth" prevents unauthorized people/systems > > from messing with your system over the network. > > > > That simple configuration is all you really need in almost > > all cases. > > > > - Mooron > > > > Omit the "maxpoll 6". ntpd will adjust its poll interval within the > limits of the default values of MINPOLL and MAXPOLL to the currently > optimal value. Tampering with the values of MINPOLL and MAXPOLL will > generally result in sub optimal performance. Typical behavior is for > ntpd to start polling at 64 second intervals (MINPOLL) and gradually > increase the polling interval. The polling interval will sometimes > increase to MAXPOLL (2^10 or 1024 seconds) if conditions are ideal. > > Translating the math I don't really follow into English, the shorter > poll intervals let ntpd correct large errors quickly and the long > intervals allow ntpd to correct small errors accurately.
I don't follow it either. NTPD appears to use something like a PID control algorithm with some filtering and clustering of the sample data. How NTPD could become more accurate with less data is something I don't understand. I doubt anyone can give a real explanation. Probably because it just isn't so. I have noticed that with bad clock hardware, such as a SUN Sparc, it does a poor job of controlling the poll interval. - Mooron _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
