[Dnsmasq-discuss] Temporary failure in name resolution when IPv6 is enabled

[Geert Stappers]

On Wed, Feb 03, 2021 at 09:27:33AM -0800, Amit wrote:
> On Tue, Feb 2, 2021 at 11:42 PM Geert Stappers <stappers at stappers.nl> wrote:
> > On Wed, Feb 03, 2021 at 07:36:43AM +0100, Geert Stappers wrote:
> > > On Tue, Feb 02, 2021 at 05:57:22PM -0800, Amit wrote:
> > > > I have been following discussions in "[Dnsmasq-discuss] v2.83 failed to
> > > > send packet: Network is unreachable" and was happy to hear it has been
> > > > resolved in dnsmasq v2.84-1 in debian testing.
> > > >
> > > > However, this still seems to affect me and I get the error:
> > > >
> > > > $  ping www.google.com
> > > > ping: www.google.com: Temporary failure in name resolution
> > > >
> > > >
> > > > In other notes, I am able to get it to work if I disable ipv6. I have
> > > > confirmed several users in our local environment see this issue as well
> > > > with the same setup. Let me know if there is anything else you need.
> > >
> > > All the links of the chain are needed.
> >
> > At least be aware there are multi links. Example of the chain:
> > * root DNServer
> > * DNServer
> > * dnsmasq
> > * client
> >
> 
> Yes, that is correct. So far there has been no change to the other
> points in the chain. To verify a downgrade to dnsmasq 2.82 was
> attempted and the system was able to resolve queries again.

Acknowledge on "2.82" does work
And I'm somewhat lost on "the system was able again"
 

> > Where is the `ping www.google.com` done?
> > Where and how is IPv6 disabled?
> >
> 
>  - The ping is done from a Debian linux laptop
>  - IPv6 is disabled from Network Manager by editing
> the configuration from the connection editor and disabling
> IPv6.
>  - Although disabling IPv6 is probably not the solution this was
> just an observation that disabling seems to allow queries to
> function again.


My guess:

} } Where is the `ping www.google.com` done?
} The ping is done at the end of the chain
} } Where and how is IPv6 disabled?
} Same machine,  magic from Network Manager
} 
} Although disabling IPv6 is probably not the solution this was just an
} observation that disabling seems to allow queries to function again

The dnsmasq machine has no or a broken IPv6 configuration.
Breaking IPv6 on the client at the end of the chain
results in a fallback (failback?) to IPv4.


The install of version 2.82  probably has some side effects,
side effects that cover or undo problems.

 
> If there are more details required, I can provide them.

Feedback on the guess is  appriciated.



Groeten
Geert Stappers
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