[ntp:questions] Re: "Proper" way to test simple, new NTP configuration?

Martin Burnicki martin.burnicki at meinberg.de
Fri May 20 12:57:41 UTC 2005


ohaya wrote:
> Hi,
> I'm trying to setup NTP on a small network consisting of all Sun Solaris
> systems.
> I'm appending a post that I just made to the Sun admin NG about our
> configuration, but after doing more reading, I'm wondering if maybe the
> problem was 'how' we did the test.
> As mentioned below, to test this, after getting all of the xntpd's up, I
> simply set the clock back on Solaris1, then watched.  Since making the
> post, I've found a couple of msgs that seem to indicate that maybe I
> should have killed the xntpd on Solaris1 (our NTP "server"), then set
> the time back on that system, then restart the xntpd.
> Can someone here comment on this?  What is the best (and easiest way) to
> determine if this simple NTP setup is actually working?

If the system time is more than 1000 seconds off your NTP server's time then
the NTP daemon terminates itself and prints a warning to the syslog that
you should first set the clock manually.

On a client you can run

  ntpdate <server> 

with <server> being the IP address of your NTP server, to get the client's
time close to the NTP server's time fefore you start (x)ntpd on the client.

In recent NTP versions you can also start ntpd with the -g parameter, which
has the same effect.

NEVER change the time manually on a machine which is synchronized by NTP. If
you want to check that a client's time is synchronized, you can run 

  ntpq -p hostname

(if you omit hostname, it defaults to localhost)
which prints the time sync status on hostname, something similar to this:

     remote    refid    st t when poll reach   delay   offset  jitter
*  .PPS.     1 u   47   64  377    0.459    0.003   1.705

if there is a '*' at the beginning of one table entry then the NTP daemon
has selected that time source as reference time source. The offset column
shows the estimated time difference between the client and the server in
milliseconds (!).

For an basic introduction to NTP, you may want to have a look at our NTP
info page at 

or the support pages at http://ntp.isc.org.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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