minimum RR TTL cache configuration

Marc.Thach at radianz.com Marc.Thach at radianz.com
Thu Jul 12 16:15:14 UTC 2001



Guy,
I think the standards say that the received TTL is the maximum that you
should cache for.  Now if you code a caching server to do otherwise then
nobody can stop you (and I guess it would be quite easy to patch that
functionality into the code).  Apart from the obvious problems when a
server is actually moved, the downside is that any DNS-based load-balancers
or redirectors will not work effectively since they rely on their responses
being short-lived.  Therefore your users may experience failures when
accessing servers which use these techniques, and obviously these failures
could last as long as the cache time you have set.
It is in the interests of the operators of Internet servers to set a
sensibly long TTL for their DNS since it minimises their DNS traffic too,
so I guess most people trust that a short TTL is only sent when it is
required and are therefore happy to observe it.
rgds
Marc TXK
________________________________________________________________________
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                    "Guy Pazi"                                                                                    
                    <guy at wanwall.co        To:     <bind-users at isc.org>                                           
                    m>                     cc:                                                                    
                    Sent by:               Subject:     minimum RR TTL cache configuration                        
                    bind-users-boun                                                                               
                    ce at isc.org                                                                                    
                                                                                                                  
                                                                                                                  
                    12/07/2001                                                                                    
                    17:16                                                                                         
                                                                                                                  
                                                                                                                  





Hi,

In order to minimize dns traffic I would like to cache received RRs for a
minimum time period; lets say one week.
Is it possible? How common is it? Am I way over standards?

Thanks
Guy








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