[ntp:questions] Re: NTP for dummies

David J Taylor david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Sun Oct 2 18:05:58 UTC 2005


Richard B. Gilbert wrote:
> David J Taylor wrote:
[]
>> As far as I can recall, the default W32time only sets the clock once
>> a week, so whilst the initial setting may be within 50msec, the
>> keeping will almost certainly not be within 50msec.  When I used to
>> use an SNTP client, I believe the same was true, as the setting
>> could be hours apart. David
>>
>>
>>
>>
> According to the Brandolini and Green White Paper  I cited, W32Time
> tries every 45 minutes until it thinks the clocks are synchronized and
> then every eight hours.
>
> If W32Time is not good enough, and it may not be, I did point out the
> alternatives.  If it works, W32Time is by far the easiest way to do
> the job; the software is installed with Windows 2000 or Windows XP,
> and the configuration is easy.
>
> The reference implementation's version of SNTP would require that he
> build from source, install, and configure. Pre-built versions of NTP
> are available for Windows and could be downloaded, installed, and
> configured..

Richard,

Thanks for that.  According to:
  http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/intmgmt/26_xpwts.mspx

the default poll interval is 604800 seconds for PCs in a workgroup, that's 
7 days.  This article:

http://support.microsoft.com/kb/q216734/

has more information, but I am unsure of its relevancy.  It seems that how 
the PC is configured for function (workgroup or domain) may affect the 
update interval.

50ms in 8 hours would be a clock accuracy of 1.7 part per million - very 
good for a PC clock.

A pre-built NTP would be my normal choice and recommendation, but 
certainly if W32time does the job well enough at least it's "standard OS" 
software.

Cheers,
David 





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