[ntp:questions] Re: Poll frequency
Richard B. Gilbert
rgilbert88 at comcast.net
Mon Mar 20 19:31:27 UTC 2006
SivaKumar Subramani wrote:
> I've found some problem in xntpd .
> I would like to know under which scenario the poll value reach to
> 1024, during this time the offset value set
> to too large. Due to this the system clock is not set properly.
> How to avoid or correct this behavior???
> I've copied the output of the ntpq peers command and
> the content of the ntp.conf file.
> ntpq -p
> remote refid st t when poll reach delay
> offset disp
> 18.104.22.168 22.214.171.124 2 u 477 1024 377 399.89 -194866
> 126.96.36.199 188.8.131.52 3 u 508 1024 377 399.69 -193036
> 184.108.40.206 220.127.116.11 3 u 482 1024 377 399.75 -194566
> server 18.104.22.168 prefer
> server 22.214.171.124
> server 126.96.36.199
> Thanks in advance.
> questions mailing list
> questions at lists.ntp.isc.org
Anything called "xntpd" is several years out of date!! Upgrade! (Sun
and other vendors are still distributing a very old version: V3-5.93e
which was released around 1998!) The current version of the software is
ntpd v4.2.0. There is a 4.2.1 "release candidate" available for beta
Your ntpd output indicates what appears to be an extremely poor choice
of servers, an extremely poor network connection or both! The potential
error in transferring time from server to client is 1/2 the round trip
delay or over 200 milliseconds in your case. The dispersion figures
(some sort off "noise" measurement) are extremely high (something below
10 would be good). Finally, the offset figures suggest that your clock
is in error by more than two days if the value is in seconds. If it's
in milliseconds, it's still far to large!! Ntpd or xntpd cannot correct
an error greater than 1024 seconds (about 17 minutes).
Set your clock as close as possible to the correct time before starting
ntpd. With your version of xntpd, your can use ntpdate to set the clock
or you can use "date" or whatever command your O/S provides for setting
Choose servers close to you in net space (low delay: MUCH lower than 400
milliseconds). If your network connection rather than the choice of
servers is your problem, try to get a better one. 400 milliseconds is
long enough to send a signal around the equator at least three times!!!!
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