[ntp:questions] ntpq -p command query

detha detha at foad.co.za
Thu Aug 1 20:46:59 UTC 2013

On Thu, 01 Aug 2013 19:46:27 +0000, unruh wrote:

> On 2013-08-01, detha <detha at foad.co.za> wrote:

>> Ping-able network connection and a responsive ntpd on the other end is
>> not the same thing. There are devices in our network that can get time
>> from the primary NTP server, but not ping it, and vice versa. It all
>> depends on network/firewall setup.
> It tells you that at the specific time that you sent out that query, there
> was an ntpd server (not an ntp server, since not all servers are ntpd, and
> thus not all servers respond to ntpq queries). But that could simply be a
> brief aberation on the part of the network and your ntp client could get a
> return packet every time is queries around that time.
> Network disconnections can be very transient. Do you really want to
> abandona a server everytime such a blip occurs? Ssurely you want to wait
> for a few poll intervals to see if the disconnection is more than
> temporary. Otherwise on a busy network you could get huge amounts of
> trashing as you keep changing servers.

Agreed, but I think the OP was more looking at checking if the server was
reachable for monitoring purposes, not for server selection. We do checks
like that, much more frequent than the typical poll interval. If something
in routing or firewalls gets mis-configured, one can sometimes fix it even
before the next poll happens, and definitely before reach ends up at 0.


More information about the questions mailing list