--Original Message-----
> From: questions-
> [email protected]
> [mailto:questions-
> [email protected]] On
> Behalf Of David Woolley
> Sent: Wednesday, December 19, 2012 3:59 PM
> To: [email protected]
> Subject: Re: [ntp:questions] Clock Offset
>
> Mischanko, Edward T wrote:
> > How can my local clock have a negative offset when none of the
> *** selected peers have a negative offset? Is it possible?
>
> It is not clear what you mean by "local clock" and "offset",
> here. For
> the normal NTP meanings of these, the offset of the local clock
> is zero
> by definition.
>
> Could you provide the ntpq, or other, output on which you are
> making
> this observation, and indicate which fields you are using.
>
> In the normal ntpd sense, the offset of the local clock is
> always zero
> and the offsets of other sources should be randomly scattered
> around
> zero, if the time is properly synchronised (the distribution may
> not be
> symmetric, but can never be one sided, once the clock is locked.
>
> Offset is measured relative to the estimated time measurement
> from the
> upstream server. It is not relative any absolute standard of
> time,
> except after adding all the intermediate errors.
>
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[Mischanko, Edward T]
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
H:\>ntpq
ntpq> peers
remote refid st t when poll reach delay offset jitter
==============================================================================
#XXX.XXX.0.1 XXX.XXX.104.1 4 u 81 256 377 1.229 -0.089 1.032
#XXX.XXX.1.1 XXX.XXX.104.1 4 u 134 256 377 2.752 -0.153 2.626
#XXX.XXX.106.1 XXX.XXX.104.1 4 u 5 256 377 14.078 -0.212 10.713
#XXX.XXX.109.1 XXX.XXX.104.1 4 u 1 256 377 1.419 -0.027 3.646
#XXX.XXX.110.1 XXX.XXX.104.1 4 u 72 256 377 4.818 1.455 0.074
#XXX.XXX.112.1 XXX.XXX.104.1 4 u 53 256 377 1.687 -0.287 2.336
+XXX.XXX.120.1 XXX.XXX.104.1 4 u 32 256 377 1.581 0.278 0.267
*XXX.XXX.121.1 XXX.XXX.104.1 4 u 9 256 377 1.445 0.568 0.079
+XXX.XXX.122.1 XXX.XXX.104.1 4 u 116 256 377 1.614 0.319 2.084
+XXX.XXX.123.1 XXX.XXX.104.1 4 u 90 256 377 1.397 0.175 0.829
+XXX.XXX.124.1 XXX.XXX.104.1 4 u 137 256 377 1.817 0.177 1.680
+XXX.XXX.125.1 XXX.XXX.104.1 4 u 13 256 377 1.637 0.319 1.317
+XXX.XXX.126.1 XXX.XXX.104.1 4 u 136 256 377 1.424 0.391 1.456
+XXX.XXX.129.1 XXX.XXX.104.1 4 u 166 256 377 1.840 0.269 2.631
+XXX.XXX.131.1 XXX.XXX.104.1 4 u 179 256 377 1.588 0.535 1.723
#XXX.XXX.134.1 XXX.XXX.104.1 4 u 127 256 377 1.566 -0.181 0.996
+XXX.XXX.255.100 XXX.XXX.104.1 4 u 4 256 377 0.595 0.390 0.893
#XXX.XXX.255.200 XXX.XXX.104.1 4 u 241 256 377 0.518 0.605 0.159
+XXX.XXX.43.1 XXX.XXX.255.100 5 u 41 256 377 1.294 0.338 1.265
#bhw-ads04.ameri XXX.XXX.242.249 5 u 49 256 377 0.526 -12.523 22.696
#bhw-ads03.ameri XXX.XXX.242.249 5 u 172 256 377 0.554 10.323 12.585
#ihe-ads01.ameri XXX.XXX.250.248 4 u 163 256 377 1.398 -20.111 15.070
#bhw-mcads01v.mi XXX.XXX.250.248 4 u 134 256 377 0.723 -4.204 11.482
#na-mc-ads01v.mi XXX.XXX.250.248 4 u 189 256 377 1.530 -0.315 3.858
ntpq> rv
associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync,
version="ntpd [email protected] Dec 18 15:57:25.96 (UTC-06:00) 12 (1)",
processor="x86", system="Windows", leap=00, stratum=5, precision=-19,
rootdelay=17.559, rootdisp=157.869, refid=XXX.XXX.121.1,
reftime=d47cefe7.6ab0443f Wed, Dec 19 2012 20:01:11.416,
clock=d47ceff7.50f120f0 Wed, Dec 19 2012 20:01:27.316, peer=30980, tc=8,
mintc=3, offset=-0.157823, frequency=1.480, sys_jitter=0.148133,
clk_jitter=0.383, clk_wander=0.023, tai=35, leapsec=201207010000,
expire=201212280000, ctr_frequency=-1.68
ntpq>
Notice individual selected peers have positive offsets, but my clock offset
after averaging is negative?
Regards,
Ed
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