[ntp:questions] Client doesn't drop failed source

Richard B. Gilbert rgilbert88 at comcast.net
Sat Jan 9 02:48:15 UTC 2010

Michael Moroney wrote:
> David Woolley <david at ex.djwhome.demon.invalid> writes:
>> Michael Moroney wrote:
>>> that synchronizes with the four clocks, and ntpq> peers shows one of the
>>> primaries with a "*" in the first column meaning it was synchronized to as
>>> time source, the other 3 show "+" as expected, meaning they are usable
>>> sources.  We disconnect the antenna of the selected clock.  As expected
>> * and + mean they are used, not just that they are usable.  The time 
>> used to discipline the clock is a weighted average of all of them.
> If it uses all of them, what is the difference between "*" and "+"?
> It still doesn't explain why the disconnected clock doesn't get dropped.

"*" designates the primary source of time.  "+" designates an "advisory" 
source.  It's available for use if something happens to the primary 

See Dave Mills' book on NTP, and RFC-1305.  RFC-1305 is for V3 of NTP. 
There's an RFC in preparation for V4 but as of the last time I heard it 
was being written by a committee and may be released sometime in the 
next decade!

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