[ntp:questions] NTP Third party client on Windows OS ?

Danny Mayer mayer at ntp.isc.org
Wed Sep 26 03:33:49 UTC 2007


Ryan Malayter wrote:
> You can also just mointor from the Windows client, and run the built
> in windows command 'w32tm' in a loop in a batch file and record the
> results for later analysis, but I have no idea how good the data would
> actually be:
>   C:\>w32tm /monitor /computers:0.us.pool.ntp.org
>   0.us.pool.ntp.org [155.97.17.169]:
>       ICMP: 50ms delay.
>       NTP: +0.0102014s offset from local clock
>           RefID: time-b.utah.edu [155.97.154.154]

This doesn't make a lot of sense. ICMP is a protocol which NTP doesn't
use. It uses UDP instead. RefID is incorrect. The RefID is
155.97.154.154. You cannot do a reverse lookup on it as if it were an IP
address. It isn't, even though it makes use of the IP address for loop
prevention/mitigation.

You have no information on the accuracy of the offset and for that
matter it's not clear what the "ICMP" delay means. w32time takes the
value handed to it and assumes that it's correct and makes no judgement
calls on the quality of the data. If that server was totally wrong, say
it was 5 minutes off, how would you tell? Yes, you can compare it to
other ntp servers but then you might as well just use ntp and ignore
w32time.

Danny



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