[169013] in North American Network Operators' Group
Re: Need trusted NTP Sources
daemon@ATHENA.MIT.EDU (Saku Ytti)
Sun Feb 9 15:30:52 2014
Date: Sun, 9 Feb 2014 22:30:33 +0200
From: Saku Ytti <saku@ytti.fi>
To: nanog@nanog.org
In-Reply-To: <11574510.7778.1391976985145.JavaMail.root@benjamin.baylink.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On (2014-02-09 15:16 -0500), Jay Ashworth wrote:
> > Then either of two servers not giving incorrect time is 0.99**2 i.e. 98%, so
> > two NTP servers would be 1% point more likely to give incorrect time than one
> > over 1 year time.
>
> That's only true if the two devices have common failure modes, though,
> is it not?
No, we can assume arbitrary fault which causes NTP to output bad time. With
two NTP servers it's more likely that any one of them will start doing that
than with one alone. And if any of the two start doing it, you don't know
which one.
--
++ytti
