[Dnsmasq-discuss] NXDOMAIN is sent instead of NODATA when querying for non-existent AAAA records

Simon Kelley simon at thekelleys.org.uk
Thu Aug 5 19:45:29 UTC 2021

On 05/08/2021 19:24, Wojtek Swiatek wrote:
> Le jeu. 5 août 2021 à 19:41, Simon Kelley <simon at thekelleys.org.uk
> <mailto:simon at thekelleys.org.uk>> a écrit :
>     OK. The problem is here: using local addresses only for domain
>     swtk.info <http://swtk.info>
>     That's an easy spot because I just fixed this particular combination.
>     I guess you have something like
>     local=/swtk.info/ <http://swtk.info/>
>     and dnsmasq is using this to return NXDOMAIN without checking that it
>     has more specific data for the query in other  types.
>     As a workaround, removing that configuration should make things work, at
>     the expense of extra trips to the upstream servers.
> Thank you. The problem is that swtk.info <http://swtk.info> is also
> declared on .info so (if I understand local= correctly), it would
> attempt to resolve mqtt.swtk.info <http://mqtt.swtk.info> on Internet.
> Which would fail.

That's fine. mqtt.swtk.info resolves to NXDOMAIN (at least it does here)
and when dnsmasq gets that answer back, it will change it into NODATA.
because it has an A record for mqtt.swtk.info derived from a DHCP
record. That should be functional in 2.78.
> The local=/swtk.info/ <http://swtk.info/> and
> address=/swtk.info/ <http://swtk.info/> combo
> fixes this.
>     This should already be fixed in the development code: if it's possible
>     for you to run
>     https://thekelleys.org.uk/dnsmasq/test-releases/dnsmasq-2.86test6.tar.gz
>     <https://thekelleys.org.uk/dnsmasq/test-releases/dnsmasq-2.86test6.tar.gz>
>     that should fix things, and doing so would be a useful test for me.
> Unfortunately, since the dnsmasq binary I use is part of a router, I
> have no way to use another version. Which, as I realize now, will be a
> major problem anyway since the issue is not a matter of configuration.

This is a major defect in the state of the world. Routers should be
updated as often and as easily as desktops and laptops, but frequently
aren't and can't be.



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