CNAME only zone?

[Mark Andrews]

In message <CAA3U4eO=EbKB2ECSS4F1=fF22rpK2XcbP7qdUA3autXxaP8y-w at mail.gmail.com>
, =?UTF-8?B?6aOO5rKz?= writes:
> 2011/12/10 Lightner, Jeff <JLightner at water.com>:
> > Is it possible to create a zone file that only contains a CNAME?
> >
> 
> Some nameservers can setup that, though it's breaking the RFC.
> 
> quote:
> Never one to let a RFC stand in the way of a solution to a real
> problem, we're happy to announce that CloudFlare allows you to set
> your zone apex to a CNAME. This allows CloudFlare users to host on
> EC2, Rackspace's Cloud, Google App Engine, or other cloud hosts and
> use their naked domain (e.g., yourdomain.com) without forcing a hack
> solution to a subdomain (e.g., www.yourdomain.com).
> 
> http://blog.cloudflare.com/zone-apex-naked-domain-root-domain-cname-supp

While you can change what a authoritative server allows the real
problem is what recursive servers do when they have a CNAME record
in the cache you you actually want resolvers to see the other records
that live beside the CNAME.

RFC 1034:
"The domain system provides such a feature using the canonical name
(CNAME) RR.  A CNAME RR identifies its owner name as an alias, and
specifies the corresponding canonical name in the RDATA section of the
RR.  If a CNAME RR is present at a node, no other data should be
present; this ensures that the data for a canonical name and its aliases
cannot be different.  This rule also insures that a cached CNAME can be
used without checking with an authoritative server for other RR types."

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org