[Dnsmasq-discuss] Upstream servers timeout

Simon Kelley simon at thekelleys.org.uk
Thu Apr 10 21:10:31 UTC 2014


On 09/04/14 22:24, Milen Pankov wrote:
> Hi,
> 
> I am trying to use dnsmasq to send requests to upstream servers for
> specific queries. My config file contains:
> 
> server=//192.168.0.4
> server=//10.0.0.16
> server=/de.example.com/192.168.0.4
> server=/en.example.com/10.0.0.16
> 
> The upstream servers are reachable via vpn connection and thus are
> sometimes slow. Dnsmasq seems to return NXDOMAIN most of the time when
> connecting the one server and fewer times when connecting the other (may
> be one is slower). The upstream servers are running dnsmasq too and I
> have admin access to them. I can confirm debugging that the requests are
> send to the right server and that this server is returning correct
> response while dnsmasq is returning NXDOMAIN. I think dnsmasq timeouts
> waiting for answer from upstream servers after a specific period of
> time. However I cannot find such option or variable. Is there a way to
> completely disable this timeout if any or change it somehow? Any other
> solution?
> 

There is _no_ timeout function in dnsmasq, (at least not for UDP
queries). If the upstream server never replies, then dnsmasq will never
reply either. Eventually, dnsmasq will recover the resources used to
handle the request, but it doesn't send an NXDOMAIN reply as part of
that. The timeout happens in the resolver library in the original requestor.

Cheers,


Simon.





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