Subject: Re: ntp problems?
To: Steven M. Bellovin <firstname.lastname@example.org>
From: Frederick Bruckman <email@example.com>
Date: 01/22/2004 09:24:39
On Thu, 22 Jan 2004, Steven M. Bellovin wrote:
> In message <20040122142317.GA14974@zoo.bernard.org>, Jim Bernard writes:
> >On Thu, Jan 15, 2004 at 03:53:02PM -0600, Frederick Bruckman wrote:
> >> On Wed, 14 Jan 2004, Steve Bellovin wrote:
> >> > server raptor.research.att.com
> >> > server 188.8.131.52
> >> Also, two servers is not a good number to have, as
> >> there's no way for the daemon to know which one is correct when they
> >> disagree.
> > Actually, the recommended configuration is to use at least 3. See, e.g.,
> > http://www.eecis.udel.edu/~mills/ntp/html/notes.html
> Understood. But if the daemon is going to misbehave that badly with
> two servers configured, what happens if one of three configured servers
> becomes unavailable?
Recalling your original post, the problem was that the two servers
you'd configured were about 800mS apart. Making any decision at all
with that information could be construed as "misbehaving". Calling
them both bad in that situation is reasonable and correct. At least
one of those servers is (or was) really messed up, but you need at
least one other source of time to know which one.