[ntp:questions] Query about NTP accuracy

Jan Ceuleers janspam.ceuleers at skynet.be
Sun May 24 08:27:46 UTC 2009


Terje Mathisen wrote:
> This is why you want ntpd to do the initial step, after first doing the 
> full vote collection from all configured servers, not ntpdate which 
> picks the first server to respond!

If that is so, then the ntpdate manpage is wrong:

ntpdate sets the local date and time by polling the Network Time Proto‐
col (NTP) server(s) given as the server arguments to determine the cor‐
rect time. It must be run as root on the local host. A number  of  sam‐
ples  are  obtained  from each of the servers specified and a subset of
the NTP clock filter and selection algorithms are applied to select the
best  of  these.

(http://www.eecis.udel.edu/~ntp/ntp_spool/html/ntpdate.html)

In other words, before ntpd was capable of being a good ntpdate 
replacement, best practice was to use a script to extract server lines 
from ntpd.conf and pass all of those on the ntpdate command line.

Cheers, Jan




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