[time-nuts] Discipline an oscillator with NTP?

Chris Albertson albertson.chris at gmail.com
Sat Jul 23 18:02:08 UTC 2011


On Sat, Jul 23, 2011 at 10:40 AM, Bob Camp <lists at rtty.us> wrote:

>  There's also the basic "do I trust the server" issue. You can indeed trust WWV as transmitted.

NTP's clock selection algorithm is pretty good.  If you choose a
diverse set of servers then NTP will only use the subset of them that
are self consistent.  "Pool" servers are assigned randomly so even if
there were many bad servers in the world the chance of randomly
picking five that were are "bad" in the exact same way is about zero.
 Typically when a server has a problem it does not match another
randomly selected ntp server.

So I think you can trust the consensus time from a set of five
randomly selected pool servers.  It would be far easier to spoof WWV,
just set up a transmitter.

-- 

Chris Albertson
Redondo Beach, California



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