[ntp:questions] NTP Performance on WINNT

Danny Mayer mayer at ntp.org
Wed Jul 29 02:45:22 UTC 2009


David Woolley wrote:
> Steve Kostecke wrote:
> 
>>> I'm just not so sure if I can absolutely count on ntpq to determine
>>> time offset of NTP synced machines...
>> ntpq does not calculate anything. It merely displays information
>> returned from the ntpd it is querying.
>>
> 
> I believe that he means the combination of ntpq and and ntpd.  The basic 
> problem is that you are trying to mesure a parameter on a system where 
> that parameter affects the accuracy of the measurement.
> 
> There is also a problem that many other people believe that software 
> clock time + offset = UTC time (possibly minus). However, when ntpd is 
> operating in the environment in which Dave Mills expects it to operate, 
> |UTC - software clock time| << |offset|.
> 
> I believe that the parameter the OP actually wants to measure is |UTC - 
> software clock time|.  As this is Windows, and Windows doesn't 
> interpolate, one would guess that he wants this value at the point of 
> the clock tick.

Windows does interpolate, the same as Unix.

Danny

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