Subject: Re: ntp problems?
To: Frederick Bruckman <fredb@immanent.net>
From: Jim Bernard <jbernard@mines.edu>
List: current-users
Date: 01/22/2004 07:23:17
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          135.207.59.17
> 
> 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.

  (Still trying to catch up on mail after the holidays.)

  Actually, the recommended configuration is to use at least 3.  See, e.g.,

    http://www.eecis.udel.edu/~mills/ntp/html/notes.html

from which I quote:

    It is vital to carefully consider the issues of robustness and reliability
    when selecting the sources of synchronization. Normally, not less than three
    sources should be available, preferably selected to avoid common points of
    failure. It is usually better to choose sources which are likely to be "close"
    to you in terms of network topology,...

The daemon goes to a lot of trouble to determine which server currently
has the best time.