[ntp:questions] [pool.ntp.org] 87 servers so far / web server configuration / some other small things

Brad Knowles brad.knowles at skynet.be
Tue Sep 16 19:25:18 UTC 2003


At 7:41 PM +0200 2003/09/16, Adrian 'Dagurashibanipal' von Bidder wrote:

>   It was reported that the nameserver caching daemon (nscd) of Sun's
>  operating system does not rotate cache entries - so, the sample config file
>  of the web site does not work, since the same server is added three times.

	This is not just an nscd problem.  Many resolvers do not 
implement round-robin, especially the Microsoft ones.  Indeed, they 
will also take only the first IP address for a name and record only 
that in their cache, so projects like that try to do any form of 
load-balancing through multiple A records for a single name will be 
seriously hurt by them.

	IMO, dain-bramaged Microsoft resolvers are the single primary 
reason why many large sites are using L4 load-balancing switches.

>   - use different names in your timeserver config (like
>          server ch.pool.ntp.org
>          server ch.time.fortytwo.ch
>          server nl.pool.ntp.org
>          server nl.time.fortytwo.ch

	IMO, this is probably the best solution overall, anyway.

>  An interesting debate was started by Tim Shoppa on the
>  timekeepers at fortytwo.ch mailing list about the quality of the pool.ntp.org
>  time service.  While I still think that anybody who really cares about
>  accuracy should not be using the pool in his ntp.conf file, but should
>  manually pick his servers, the concerns that the zone should be quicker to
>  drop obvious falsetickers and unreachable servers are valid.  I will play
>  around with a nameserver containing the whole pool, ntpq, and a database
>  backend to store the pool information to see how I can automate the
>  monitoring further.  I won't promise a date here, though - everybody knows
>  that 24h/day are just too little time to do everything we want...

	Problem is, we need this kind of monitoring to be done at many 
sites across the 'net.  Your view of how reachable or poorly 
operating a particular server is may have little bearing on how 
someone else might view that same server -- all due to network 
issues.  To get a proper overall view, this needs to be done at 
multiple sites so that we can try to average out network effects.

-- 
Brad Knowles, <brad.knowles at skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
     -Benjamin Franklin, Historical Review of Pennsylvania.

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