Wildcarded CNAMEs (slightly OT)

Bill Jonas bill at billjonas.com
Wed Jun 7 18:18:58 MST 2006


I ran into a situation at work today when configuring DNS for a
customer.

Is it permissible to have a wildcarded CNAME?  I'm talking about,
conceptually, a zone file that looks like this after the SOA record:

  example.com.  IN NS     ns1.foo.bar.
  example.com.  IN NS     ns2.foo.bar.
  example.com.  IN CNAME  example.net.
*.example.com.  IN CNAME  example.net.

BIND (We're using some version of BIND 9, but I don't have access to
our name servers) didn't answer lookup requests for example.com or
www.example.com.  The logs (viewed by the admin in charge of those
servers) didn't show anything amiss, I don't think.

Google wasn't too helpful with 'wildcard cname' (no quotes).  The
closest I came was RFC 1912 (http://rfc1912.x42.com/), section 2.4, but
it still didn't quite fit.  Other results were on mailing lists for BIND
and other DNS software discussing implementation errors and bugs.

I got around the problem by changing those CNAME records to A
records, but I'm really curious if wildcarded CNAMEs are prohibited, and
in what RFC.  If not, is this a bug in BIND?  (I'd ask about the
resolver while I'm at it, but it would have the least to do with the
problem, and lookups timed out on Windows, FreeBSD, and Linux.)</lj-cut>

Thanks for any light anyone can shed on this.

-- 
Bill Jonas    *    bill at billjonas.com    *    http://www.billjonas.com/
"It's a dangerous business, Frodo, going out your front door.  You step
into the Road,  and if you don't keep your feet,  there  is  no knowing
where you might be swept off to."  --  Bilbo Baggins
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