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

David Woolley david at ex.djwhome.demon.invalid
Mon Jan 11 23:13:35 UTC 2010

> I see nothing "wrong" with having several, {I've done it}
>  as long as it is understood that are always included in
>  the combining algorithm and don't get discarded.  AFAICT

At least in 4.2.4p4, they are never included in the combining algorithm. 
  If one ignores some complications due to local and PPS clocks, the 
first peer found (I'm not sure if the list is sorted at this point) is 
the only source of time used.  Any redundant prefer peers are excluded. 
  clock_combine only appears on the branch that is executed when there 
is no prefer peer.

The other big effect of prefer is that candidates that have better 
metrics than the worst prefer peer are selected, although I think this 
is only significant if there is PPS peer that would otherwise have been 

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