[Dnsmasq-discuss] Fwd: mixing synth-domain and auth-domain does not appear to work for me.

[David Beveridge]

On Thu, Apr 3, 2014 at 6:24 AM, Simon Kelley <simon at thekelleys.org.uk> wrote:
>
> On 02/04/14 11:46, David Beveridge wrote:
> > So I have a few static hosts defined in /etc/hosts and I want to
> > serve authoritative records for them.
> > I also have some machines which get address via dhcp and slaac which I want
> > to publish using synth-domain.
> >
> > Each option works alone, but when I mix the options
> > eg
> > auth-zone=thekelleys.org.uk,192.168.0.0/24
> > synth-domain=thekelleys.org.uk,192.168.0.0/24,internal-
> >
> > with synth-domain only
> > # dig internal-192-168-0-56.thekelleys.org.uk @223.27.66.79
> > ;; ANSWER SECTION:
> > internal-192-168-0-56.thekelleys.org.uk. 0 IN A 192.168.0.56
> >
> > with both defined, no answer is returned.
> >
> >
> > The behaviour is the same for Ipv6.
>
> This is, I think, just an oversight. synth-domain certainly generates
> "Locally defined DNS records" which is what the auth-zone is specified
> to contain.
>

So if the auth-domain exists and the lookup fails there it does not try to
do a lookup in synth-domain.  I'm not sure how commonly people
might want to do that.

> >
> > regards,
> > dave.
> >
> > PS: any reason why synth-domain is limited to /64 for IPv6?
>
> Prefix length has to be greater than or equal to 64, is that what you
> mean?  It's about implementation convenience. C doesn't provide a
> integer data type larger than 64 bits for doing masking. of the
> address-part.
>

Fair enough.  So I have a copy of dnsmasq running on my bind dns server
just to handle the synthetic reverse (which bind can't do), so each /64
needs to be individually configured in dnsmasq.  It's good to know why.

I can't just get lazy and synth a whole /48 or /32.
Probably out of scope for what dnsmasq is designed for anyway.

dave

> Cheers,
>
> Simon.
>