[ntp:questions] Magice Server Numbers: 4,5,7,9

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Fri Sep 16 12:20:10 UTC 2011

Doug Calvert wrote:
> Hello,
>   From time to time people mention that the magic number of servers is
> 4,5,7 and nine. However I can not find a reference or explanation for
> the magical properties. Can anyone explain the background/basis in
> general? And specifically how is five or seven preferable to six?

Afair, the first two are 4 and 7, the number of servers you need to 
survive one or two falsetickers, i.e. not just loss of a server or two.

Byzantian generals is a search term.


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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