[ntp:questions] ntpq -p command query

Charles Swiger cswiger at mac.com
Tue Jul 30 18:15:52 UTC 2013


On Jul 30, 2013, at 7:24 AM, Biswajit Panigrahi <BP00106533 at TechMahindra.com> wrote:
> Both are communicating properly. I would like to test when the
> connectivity between those two goes down, after how much time the
> "reach" option in ntpq -p command becomes zero.

The "reach" field is a 1-byte large bitmap which tracks whether
the last 8 NTP polls got a reply, so the answer to your question is:

   8 * poll interval

> The reach option will still  keep on increase to 377 then gradually
> decreases to zero. The time duration to come to zero is almost 20
> minute.

That seems about right if you'd just restarted both ntpds and then stopped
the server once the client got to 377, as the client wouldn't have reached
default maxpoll = 10 interval of ~17 minutes.  If you'd waited longer,
it would likely take a bit over two hours to clear the reach field.

> Can we reduce the time gap ?

Yes, you can reduce maxpoll to have reach field zero out more quickly.
There are tradeoffs involved in doing so, however.


More information about the questions mailing list