[ntp:questions] Re: Windows timekeeping - sudden degradation - why?

John Allen allen{at}vo{dot}lu at ntp.isc.org
Sat Dec 10 00:07:11 UTC 2005

This thread has intrigued me because I think I may have a similar problem.

My Windows XP system ran Terje's NTP 4.2.0a happily from May 2004
until sometime in the last month - I can't be as precise as David Taylor.
My PC was synchronizing to my server running Linux also with NTP 4.2.0.
Using NTPMonitor occasionally, I was seeing offsets typically 20-50 ms from 
reliable low-stratum servers - more than satisfactory for me and I paid very 
little attention to it. The SP2 upgrade went smoothly some months ago.

Sometime in the last few weeks NTP on the PC has completely lost the ability to 
synchronize with the server. I'm seeing offsets increasing by several seconds an 
hour - they are consistent across my server and distant stratum 1-3 servers. The 
offsets are alway negative which means (I think) that the PC's time is running 
faster than the server.

I've tried all the obvious things - installing later and earlier versions of 
ntpd, removing applications running in the background...none of these seems to 
affect the behaviour of NTP in the slightest. I've made some fairly major 
changes to the PC in the last 2 months, some of which I'm not keen to reverse - 
like installing Visual Studio C++ Express Edition, .NET 2.0 runtime, Windows 
SDK, BIOS upgrade, so there are plenty of things which could have clobbered NTP.

Here is the output from
ntpq -c "rv 0" deeley
assID=0 status=c074 sync_alarm, sync_unspec, 7 events, event_peer/strat_chg,
version="ntpd  2004 May 07 8:37:39  (1)"?, processor="unknown",
system="WINDOWS/NT", leap=11, stratum=16, precision=-20,
rootdelay=0.000, rootdispersion=32.160, peer=0, refid=STEP,
reftime=00000000.00000000  Thu, Feb  7 2036  7:28:16.000, poll=4,
clock=0xc7449871.72e5796b, state=3, offset=0.000, frequency=0.000,
noise=2299.254, jitter=870.642, stability=0.000

(only 45 minutes after restarting the NTP service)

Some of this looks a bit strange so maybe I'm out of my depth here, but I'm 
curious to know if this could be a similar issue to David Taylor's.



John Allen
Bofferdange, Luxembourg

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