[ntp:questions] Re: Sufficient # servers to sync to

David Schwartz davids at webmaster.com
Sat Mar 19 21:10:50 UTC 2005

"David L. Mills" <mills at udel.edu> wrote in message 
news:d1hqk9$861$1 at dewey.udel.edu...

> It's not true for three servers. Assuming one is falseticker, the other 
> two cannot from a majority clique in the voting process. You need at least 
> three alleged truechimers for that. I hesitate to cite Leslie Lamport, the 
> source of the Byzantine Generals problem, on which this algorithm is 
> based, but the paper is among the citations at 
> www.eecis.udel.edu/~mills/biblio.html.

    I hate to say this, and it's quite possible I'm wrong, but it seems to 
me that this is based on an erroneous understanding of the Byzantine 
Generals problem and its solution. If you have three servers, this is 
analogous to the Byzantine Generals problems with *four* entities, the three 
servers you have, and *you*. With four entities, each entity has three 
others to look at. If two are correct, they can outvote the third.


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