[dnsdist] Caching reverse lookups

Jon Radel radelj at folioinvesting.com
Tue Mar 19 21:02:52 UTC 2019

On 3/19/19 4:56 PM, Alan Clegg wrote:
> On 3/19/19 4:51 PM, Jon Radel wrote:
>> To add a bit more information:  It turns out to matter how I do the
>> query.  If I do the query using dig 9.11.3 as shipped with Ubuntu, it
>> doesn't get cached.  If I do the query with host, it does get cached.
>> Which lead me to the thought that being a bit less clever with dig
>> options might help.  With the +noedns flag, bind queries are also cached.
>> I'd love an explanation of why this is.
> DNS Cookies.   https://tools.ietf.org/html/rfc7873
> AlanC

Ah, indeed the +nocookie flag on bind is sufficient to change the 
behavior.  What value is there to caching the response in this case?  I 
would hope that cookie values wouldn't repeat often enough to make 
caching of value.


--Jon Radel

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