Re: ntp synchronisation failed

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Date: Tue, 29 Jun 2004 21:23:09 -0700
To: For users of Fedora Core releases <fedora-list@redhat.com>

On Tue, Jun 29, 2004 at 03:48:31PM +0200, Corné Beerse wrote:
> T. Nifty Hat Mitchell wrote:
> >On Thu, Jun 24, 2004 at 08:34:02PM +0200, Eric Tanguy wrote:
> >
> >
> >>In the boot process the ntp synchronisation failed whereas after the
> >>time synchronization is all right. Why ? may be because i use
> >>firestarter ?
> >
> >
> >If you have friends running Linux/Fedora exchange NTP privileges.
> >
> >First look at how ntpd is started for you.
> >
> >In general you will find that the initial connection using ntpdate
> >times out for various normal reasons. As a result the return status
> >is an error.
>
> You can chech for this behavoure to do a ping to the ntp-server. If you
> ping 3 to 5 times, you will see the first ping takes longer than the
> others. Most likely, after this ping (before the ntpd-start) the first ntp
> query also succeeds.
>
> Specially if you call the ntp-server by name, the IP-address is not cashed
> jet and hence a dns-query must be made. Since it is at boot time, most
> likely all routings and such also need to be setup.
>
> If you have pinged the ntp-server (even only once!), all routers and
> name-caches are filled and the ntp-query can go strait on and will be
> substantial faster.
>
> >
> >If you check back +15 min later things will be fine when ntpd has had time
> >to make some connections.
>
> However, if you start ntp only 15 minutes later, it is likely that the
> first call still is a little late.
>
> >
> >Note that /etc/init.d/ntpd first starts ntpdate then ntpd. It is not
> >uncommon for ntpdate to fail in the early stages of booting a system
> >for a list of reasons...
>
> Not necessarily, newer ntpd-s have ntp-date build in and do that themself.
> If it is done separatly, this ntp-date will walk the paths for the next
> ntpd-s.
>
> >
> >Do, find a ntp time service local to you.
> >Based on the mail headers, perhaps ntp.univ-nantes.fr
> >
> >or look here... http://www.eecis.udel.edu/~mills/ntp/clock2b.html
>
> >If you have friends running Linux/Fedora exchange NTP privileges with each
> >other!

Yes the way that the current scripts start the ntp time daemon might
be improved. I expect when ntpdate is eventually removed the change
will take place.

I spent a little time looking at it a year or so back and the standard
pair of redhat time servers seem to be overloaded enough that the
initial connections always time out and a RED FAIL was just too common
for me. I looked for closer and more reliable time servers.

It really does help to exchange keys with other Linux friends and as a
group get connected to a pair of near by level one or two hosts depending
on how large the group is.

If your ISP does not document a NTP time host ask.

NTP is such a high quality service that a pair of level 3 servers will
provide exceedingly good time of day references.

Of interest there is a multicast/broadcast ntp protocol. Opening the
firewall to this port might find the service already active.

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