[ntp:questions] Offsets in NTP vs. SNTP

Dennis Hilberg Jr dont at spam.me
Sun Jul 29 19:09:47 UTC 2007

Brian Garrett wrote:
> I have never seen this question answered anywhere, so I hope someone here 
> can either answer, or point me in the right direction in TFM that I didn't R 
> :)
> When I use an SNTP client on my Windows XP box, after one or two settings 
> the client displays an offset  of a few milliseconds (usually <5).  However, 
> if I then immediately check the offset with NTP (using either the NIST app 
> available on their website or Meinberg's NTP monitor), I get an offset in 
> the 20-30ms range.  Why would the two offsets be different?  The delay 
> hasn't changed.  I know the two protocols function differently but they 
> should still be reading the same time, no?
> TIA,
> Brian Garrett 

You might try reading this:

You also might read RFC 2030, which defines SNTP:

Dennis Hilberg Jr <timekeeper(at)dennishilberg(dot)com>

NTP Server Information: http://saturn.dennishilberg.com/ntp.html

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