The RFC or the reason why you can not create CNAME record for the "root record"

Jim Reid jim at rfc1035.com
Tue Jun 1 17:56:29 UTC 2004


>>>>> "Phil" == phil-news-nospam  <phil-news-nospam at ipal.net> writes:

    >> On Mon, 29 Mar 2004 05:12:06 -0500 Barry Margolin
    >> <barmar at alum.mit.edu> wrote: RFC 1034 says: "The domain
    >> system provides such a feature [aliases] 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."   Since a delegated zone
    >> name is required to have SOA and NS records, if it also
    >> had a CNAME record it would violate the restriction in the
    >> last sentence.

    Phil> So how do we fix this?

Rewrite RFCs 1034 & 2181 and get them accepted by IETF and then
adopted as standards. Then have everyone's DNS software support your
rewritten standards. After that, get all the world's deployed name
server software -- not just name servers! -- update/migrate to the new
standards. In other words, not in our grandchildren's lifetime.

    Phil> I think a hack/patch is the only way.

You might think that. But you'd be wrong. Sure, you can come up with a
kludge for your name server to make it violate these fundamental DNS
standards. This won't help everybody else's DNS software. That may
fail or give undefined behaviour when it gets a response from your
name server that has an owner-name as a CNAME and some other record
type, something that RFC1034 and RFC2181 clearly state isn't allowed.
Even if all this came to pass, it still wouldn't be enough. There
could well be applications software which looks up CNAMEs directly.
This stuff could get confused if a response returned A or AAAA records
(or whatever) as well as the desired CNAME.


More information about the bind-users mailing list