[ntp:questions] Packet timestamps when using Windows-7/Vista

David J Taylor david-taylor at blueyonder.delete-this-bit.and-this-part.co.uk.invalid
Tue Dec 15 14:36:25 UTC 2009

> Martin,
> I've added a test to my program to see whether the value from 
> GetSystemTimeAsFileTime ever steps backwards, and it hasn't done so in 
> my testing so far.  So I remain unsure why, on a system without the 
> interpolation code, I'm seeing the TX time before the RX time. 
> Certainly would be nice to have someone confirm the result - a default 
> installation on a Vista or Windows-7 should show this.
> Cheers,
> David

There is a brief write-up of the program, and sample plots from "good" and 
"bad" NTP servers, here:


Martin has been able to confirm the timestamp sequence issue using 
different test software running on a different OS.


More information about the questions mailing list