[ntp:questions] Re: why difference about 200ms with time.nist.gov

Ronan Flood ronan at noc.ulcc.ac.uk
Wed Mar 29 14:47:54 UTC 2006


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote:

> flyfatpig at gmail.com wrote:
> > I built a time server with redhat 7.2 and ntp 4.2.0 and Motorola M12T.
> > The time server works well.But when I  sync with time.nist.gov ,I found
> > my time server is about 200ms later .who can tell me why?
> > 
> > 
> > [root at gt4 lxh]# ntpdate -q 192.168.2.7
> > server 192.168.2.7, stratum 1, offset 78.759011, delay 0.02599
> > 29 Mar 15:37:32 ntpdate[1090]: step time server 192.168.2.7 offset
> > 78.759011 sec
> > 
> > [root at gt4 lxh]# ntpdate -q time.nist.gov
> > server 192.43.244.18, stratum 1, offset 78.958525, delay 0.26364
> > 29 Mar 15:38:24 ntpdate[1092]: step time server 192.43.244.18 offset
> > 78.958525 sec
> > 
> > [root at gt4 lxh]# ntpdate -q clock.isc.org
> > server 204.152.184.72, stratum 1, offset 78.980319, delay 0.20029
> > 29 Mar 15:45:16 ntpdate[1111]: step time server 204.152.184.72 offset
> > 78.980319 sec
> > 
> > where 192.168.2.7 is my time server .


> Next, you have in no way demonstrated that you (or NIST) are off by 200 
> milliseconds!  You are showing an offset of 78 milliseconds.

No, that's an offset of 78.x seconds, presumably seen from another,
unsynced, local machine.  It's the difference between the offsets
that shows the local server 200ms or more behind the others.

-- 
                      Ronan Flood <R.Flood at noc.ulcc.ac.uk>
                        working for but not speaking for
             Network Services, University of London Computer Centre
     (which means: don't bother ULCC if I've said something you don't like)




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