[ntp:questions] NTP and SNTP in the end, give me precision of 1ms?

David Woolley david at ex.djwhome.demon.co.uk.invalid
Sat Sep 13 21:37:08 UTC 2008


Unruh wrote:

> 
> An SNTP canot be a server if it is not tied to a hardware clock.

s/cannot/should not/  Pre-Windows 2003 versions of w32time are examples 
of some things that are commonly used in violation of the rule.

Generally, though, Unruh is on the right lines; whilst you can make some 
assumptions about the abilities of an NTP client, you can make none 
about those of an SNTP one, as the specification says nothing about how 
it uses the measurements it makes.  (NTP is still at the mercy of 
unusual configurations and hardware, software and networking issues.)

SNTP clients are often used with very long poll intervals, that are not 
compatible with 1ms tracking.




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