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

David Schwartz davids at webmaster.com
Sat Mar 19 23:55:35 UTC 2005


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message 
news:vP6dndrj_8jgOaHfRVn-ug at comcast.com...

> Aren't you assuming that the "*you*" already knows what time it is?

    No. The Byzantine Generals algorithm does not assume that any of the 
lieutenants already know the answer. In the case of NTP, the General is UTC 
and the Lieutenants are the time servers.

> The objective of running NTP is to find out what time it is!

    Right.

> It is very useful to start up with a more or less correct estimate of the 
> correct time but it is by no means required.   If you use four servers, of 
> which at least three are working properly, you will eventually get to the 
> correct time.

    And if you use three, of which two are working properly, you will too. 
Those two will agree. The third will either agree or disagree. If agrees, no 
harm. If disagrees, he's outvoted.

    DS





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