[Dnsmasq-discuss] NODATA-reply on AAAA-CNAME-queries where no A-record exists

[Tom Fernandes]

Hi all,

I'm having an issue where an AAAA-Lookup on a CNAME results in NXDOMAIN-IPv6 
instead of NODATA.

Because of this behaviour the DNS-Server between the client and dnsmasq-server 
(where the domain I'm talking about resides) will answer all subsequent 
request to the A-record of that domain with NXDOMAIN as well.

I have the following configuration:

local=/media.foo.bar.local/foo.bar.local/bar.local/
domain=bar.local,192.168.58.186,192.168.58.193
dhcp-range=tag:bar.local,192.168.58.186,192.168.58.193,24h
dhcp-match=set:bar.local,option:domain-name,bar.local
cname=media.foo.bar.local,foo.bar.local

It basically means that
- when a client requests a DHCP-address with DHCP-options
  domain-name=bar.local and hostname=foo it will receive an IP and will be put
  in into the DNS with the hostname foo.bar.local
- an additional hostname (CNAME) will be created (media.foo.bar.local)
  pointing to foo.bar

I use this setup to rollout servers without having to configure IPs anywhere.

This works fine as long as only A-records are being requested. But as soon as 
I request once the AAAA-record for media.foo.bar.local it all breaks:

dnsmasq answers with NXDOMAIN-IPv6 for the AAAA-record media.foo.bar.local. 
The Windows-DNS-Server - which is between the client and dnsmasq - receives 
that answer and will return NXDOMAIN for all further A-record-requests of 
media.foo.bar.local.

This behaviour may even be RFC-conform as there is no A-record for 
media.foo.bar.local.

So I see two possible solutions to this issue for me:
- tell dnsmasq to return NODATA instead of NXDOMAIN-IPv6 to the request of the 
  CNAME of media.foo.bar.local or
- dynamically create an A-record for media.foo.bar.local which points to the 
  same IP-address as the A-record for foo.bar.local. I would need to do this 
  dynamically because I don't want to configure IP-address anywhere manually.

Any ideas?

regards,


Tom