[ntp:questions] Utility to measure time drift

Steve Kostecke kostecke at ntp.org
Wed Jul 2 20:37:24 UTC 2008

On 2008-07-02, Maarten Wiltink <maarten at kittensandcats.net> wrote:
> "jkvbe" <jkvbeNOSPAM at yahoo.com> wrote in message
> news:g4ggcn$5gj$1 at aioe.org...
>> I'm looking for a utility like clockdiff(8)  to measure the time
>> delta between different machines. The utility itself should run on
>> Windows, but the machines under investigation are running Linux.
> The usual approach is to set up a machine that has all the machines
> under scrutiny as servers in its NTP configuration, possibly all
> marked noselect - I'm not sure about that bit.

noselect is correct. As in:

server something_you_are_monitoring noselect

> Ntpq -p will then tell you the offset to them all, relative to a
> single base (the monitoring server's own notion of time).

ntpq -p is just a snapshot

Enable peerstats logging you to collect long term data for analysis.

> Note that this is subject to all the vagaries of normal NTP life.
> If the DSL connection to one server is heavily overloaded, the
> offset will reflect that.

The time delta between the machines under test will. of course, be
affected by network conditions between them and the monitor and their
time sources.

Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/

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