[ntp:questions] [Q] Why do many time servers time out on queries from ntpq -p?

Dennis Hilberg, Jr. timekeeper at dennishilberg.com.invalid
Sat Apr 12 05:44:35 UTC 2008


Maurice Volaski wrote:
> I've been trying the peers command in ntpq on a number of time 
> servers and finding that for as many that do respond, there are about 
> an equal number that do not. An example of a failing response is:
> 
> ntpq> host sundial.columbia.edu
> current host set to hickory.cc.columbia.edu
> ntpq> peers
> hickory.cc.columbia.edu: timed out, nothing received
> ***Request timed out
> 
> I can reproduce identical successes and failures from 3 computers 
> running different OSs on independent networks.
> 
> These I've tried work just fine:
> timex.cs.columbia.edu
> time.euro.apple.com
> lain.ziaspace.com
> ntp.nblug.org
> ntp1.cs.wisc.edu
> clock1.unc.edu
> 
> But these time out:
> sundial.columbia.edu
> time.apple.com
> morose.quex.org
> ntp.sycharlutheran.org
> ntp.bytestacker.com
> ntp1.kansas.net
> 
> All of the above were tested and gave the same results on
> kennedy1.aecom.yu.edu (Linux with ntpq 4.2.4p4 at 1.1520-o)
> fluxsoft.com (FreeBSD with ntpq 4.2.0-a)
> ool-45766590.dyn.optonline.net (Mac OS X with ntpq 4.1.1 at .786)

If the server operator has 'noquery' specified in the default restriction it 
will prevent the server from responding to ntpq and ntpdc.

Interestingly, I actually wrote a script that uses 'ntpq -pn' to randomly 
query client entries in my ntp_clients_stats log file. I've found that only 
about one percent respond on average.

Dennis

-- 
Dennis Hilberg, Jr.     \  timekeeper(at)dennishilberg(dot)com
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