[Dnsmasq-discuss] misunderstanding negative caching

[Simon Kelley]

an ICMP no route to host or similar should cause option b)


Simon.


On 04/04/2019 22:25, Alex Litvak wrote:
> Thank you for your reply Simon.  If DNS service is down and dnsmasq
> receive immediate icmp reject will this be  a) cached, b) handled as
> immediate error with next name server tried immediately, or c) just a
> timeout within system defined time out?
> 
> We are looking to avoid a delay with failing / overloaded DNS servers,
> whence asking all those weird questions.
> 
> Thanks again,
> 
> On 4/4/2019 10:39 AM, Simon Kelley wrote:
>> On 27/03/2019 00:32, alexander.v.litvak at gmail.com wrote:
>>> Dear list,
>>>
>>> I configured dnsmasq with enabled negative cache and neg-ttl 600.  I
>>> attempted to use it with a query that times out (configured fake dns
>>> servers
>>> in the config file).  When I ping a host, I have NXDOMAIN in logs. 
>>> However,
>>> every time I ping it dnsmasq asks those servers to resolve the host.
>>> Shouldn't I get rejection immediately based on dnsmasq negative cache?
>>>
>>> Thank you in advance,
>>>
>>>
>>>
>>
>> A time-out will not be cached, which is generally sensible, I think.
>>
>> Simon.
>>
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> 
> 
> 
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