[ntp:questions] Re: To many servers

Richard B. Gilbert rgilbert88 at comcast.net
Fri Apr 1 19:03:53 UTC 2005


Joshua Coombs wrote:

>Is there such a thing as configuring too many servers, or is the general 
>theory the more the merrier?
>
>Joshua Coombs 
>
>
>  
>
I believe that there is a limit of ten.   Four is the minimum to protect 
you against one falseticker.  Five protects you against two falsetickers 
and seven protects against three falsetickers.  Two servers is the worst 
possible configuration, for it is written that "A men with two clocks 
can never be certain what time it is!"

Careful selection rather than quantity is the key to success.   The 
maximum error in transmitting time from a server to a client is one half 
the round trip delay so you want low numbers for delay.   Some network 
servers seem to be rock solid; i.e. they have a consistent notion of 
what time it is.  Other servers seem to wander +/ 25 to 30 milliseconds 
around the correct time.   Keep an eye on the servers you are using and 
see how they compare with each other, then replace the worst one if you 
can find a better one.

Configure four or five of the best you can find.



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