[c-nsp] NTP Servers
Jimmy Hess
mysidia at gmail.com
Mon Jul 2 01:59:42 UTC 2012
On 7/1/12, PC <paul4004 at gmail.com> wrote:
> If your application requires sub-5 second accuracy, (such as end of a
> banking day), then Windows NTP is unsuitable for the purpose.
Looks like CYA on Microsoft's part.
That i've seen, Windows NTP in physical environments with a hardware
system clock not having issues consistently provides accuracy better
than +/- 0.5 against the time source it's synced with, but in
virtual environments, which have incompatibilities with high
sub-second RTC accuracy in the first place, neither Windows nor Unix
NTP services are able to provide that consistently without much
tinkering.
If it's absolutely critical that you have sub-5 second accuracy,
even Unix NTP is not to be considered good enough, you need highly
accurate hardware time source, something more accurate than the usual
system clock you find in a PC or server. Unix NTP can only do so much
to correct for a broken system clock; although it does do a very
good job disciplining PC real-time clocks that consistently run a bit
too fast or too slow, ultimately the
personal computer clocks can at times be unreliable....
If they were perfect, you wouldn't need time sync in the first place;
just set them once,
and correct the annual 0.01 seconds worth of error once a year....
--
-JH
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