[ntp:questions] Server offset included in served time?
Richard B. Gilbert
rgilbert88 at comcast.net
Fri Sep 12 21:29:01 UTC 2008
David Woolley wrote:
> Howard Barina wrote:
>> Does an NTP servers take into account it's estimated offset in serving
> There seem to have been a lot of questions asked in the last month that
> are based on the false assumption that "offset" measures the difference
> between the local clock and true time. Has someone published a
> misleading document, somewhere?
>> to others? If I am a server and think I am 1.5 milliseconds off from
>> time, will I include this in the timestamps of my ntp replies to others?
> An NTP client never thinks that its time is wrong. If it did, it would
> be admitting that the NTP algorithms are wrong. Therefore the server
> always serves its client's idea of the time.
> The "offset" should always be within the statistical error from the
> current measurement history (if ntpd suspects otherwise, it steps,
> and/or reduces the poll interval, to try to rapidly re-acquire that
> condition). Immediately after startup, there will be little history, so
> quite large offsets will still be consistent with that history.
> There are people who who argue that the NTP algorithms are fundamentally
> flawed and don't give the statistically best time in real world
> situations. I think they have some credibility, but NTP's inventor,
> does not.
I hope you did not mean to say that David Mills has no credibility but
what you wrote sure reads that way!!
More information about the questions