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All,

One of the computers on my network runs Windows Embedded Standard and is running the meinberg NTP client and gets its time directly from a GPS clock. The service is set to run automatically and when it restarts it is very close to the GPS clock/"correct" time. However, the next day I notice that it is off by more than an hour! I restarted the NTP client service again, and again the time is good. This time I ran ntpstatus and outputted the results to a log so I could watch them over time, and here is what I am seeing: the offset field kinda goes back and forth for a few hours around the range ~ [-30, 20000]. The offset will grow and then it will shrink again. However, after some handful of hours, the offset just starts to grow, and it doesn't stop. Almost exactly 24 hours after I had started the logging, I am now reading an offset of 3,729,xxx. I'm not sure what units those are, but my clock was off by about an hour. I restarted the NTP client service, and sure enough the clock corrected itself. Any input on how to debug or narrow down this issue would be much appreciated. We have several other machines that run the same client connected to the same clock without any issue. Our only option in the config file is the ip of the gps clock and the iburst option, which was the standard when we installed it.

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  • When you say "connected to the GPS clock", you mean a physical wire that carries Pulse Per Second data, right? You do not mean that the NTP Client has some Network device as it's preferred Server.
    – Chris S
    Jul 3, 2013 at 13:05
  • Yes there is a physical wire, although it is not direct; there is a cisco switch in the middle, but other computers on the network that also use the same ntp client are not having this issue...only one machine seems to lose it.
    – prelic
    Jul 4, 2013 at 0:55
  • I'm pretty sure you're talking about an Ethernet connection, and not a PPS Serial connection... Is the Windows Time service disabled? Is this server part of a domain?
    – Chris S
    Jul 4, 2013 at 2:00
  • Yes I'm talking about an ethernet connection, not a serial connection. Windows time service is disabled (according to services.msc). This machine is part of a domain (not the PDC), but it is not getting it's time from the PDC. At least it's not supposed to be. When it gets 'off', it doesn't match the meinberg clock or the PDC's clock. Maybe it's the motherboard of the computer? It's one of the only distinguishing factors of that box.
    – prelic
    Jul 5, 2013 at 22:54

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