About the prefetch function within bind 9.10.

Mark Andrews marka at isc.org
Sun May 18 07:49:56 UTC 2014


If there is a query in that 9 second window then named will make a query to repopulate the cache. If there is not a query then the records will expire. You only want to prefetch records that are being queried for regularly. 



On 18/05/2014, at 17:18, Hongyi Zhao <hongyi.zhao at gmail.com> wrote:

> What do you mean by saying that "Prefetch does not cause named to ignore TTLs"?
> 
> I think in my case, I have set the preftch option like this:
> 
> --------------
> prefetch 2 9;
> --------------
> 
> This will enable the prefetching for all of the entries with the TTL larger that 2 seconds, (in my case, the TTL is 60 seconds, so the prefetch will be enabled for this entry).  The digit 9 triggering condition for doing the prefetching.  In my case, it should mean that when 51 seconds elapsed for the entry, i.e., 9 = 60 - 51,  the bind will prefetching the record, and then the record will have a full TTL, i.e., 60 seconds for this case again. 
> 
> Am I wrong about the meaning of the prefetching function of bind or not?  
> 
> Regards
> Zhao   
> 
> 
> 2014-05-18 13:46 GMT+08:00 Leonard Mills <lenm at yahoo.com>:
>> Taking the CNAME line in the response, please notice that the published TTL is 60 seconds.  Prefetch does not cause named to ignore TTLs.
>> 
>> hth,
>> Len
> 
> 
> 
> -- 
> Hongyi Zhao <hongyi.zhao at gmail.com> 
> Xinjiang Technical Institute of Physics and Chemistry
> Chinese Academy of Sciences 
> GnuPG DSA: 0xD108493
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