Subject: Re: ntp problems?
To: Jim Bernard <>
From: Steven M. Bellovin <>
List: current-users
Date: 01/22/2004 10:15:12
In message <>, 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
>> > server
>> 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.,
>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 thr
>    sources should be available, preferably selected to avoid common points of
>    failure. It is usually better to choose sources which are likely to be "cl
>    to you in terms of network topology,...
>The daemon goes to a lot of trouble to determine which server currently
>has the best time.

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?

		--Steve Bellovin,