[Techtalk] Stupid DNS questions

Kai MacTane kmactane at GothPunk.com
Tue Mar 9 00:19:08 EST 2004


At 3/8/04 09:37 PM , Mary wrote:


>If the master vanishes, the slave will continue making its puzzling.org data
>available for 3600000 seconds.
>
>I believe the slaves will attempt to get new zone data as often as the 
>refresh field (10800 seconds in this case) specifies.

IIRC, they normally try to get it once per refresh time. But if a normal 
refresh fails, then they retry it once per retry time. So, in the case of a 
server that's a secondary NS for puzzling.org, I think it would go 
something like this:

Suppose the server daemon is started at midnight on Sunday. It immediately 
queries the master, and gets the zone file. Then it tries again at 3AM. 
Then again at 6AM and 9AM. Then let's suppose that at noon, it tries, but 
fails to get through. It then tries again at 1PM, 2PM, and so on, until it 
successfully gets the zone transfer. (And if it never manages to get 
through, then it just keeps on serving out the old data until nearly two 
months later.)

I must confess, I don't quite get the TTL.

                                                 --Kai MacTane
----------------------------------------------------------------------
"Death and money make their point once more,
  In the shape of philosophical assassins..."
                                                 --Shriekback,
                                                  "Gunning for the
                                                   Buddha"



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