not typing in www

Mark Andrews Mark_Andrews at
Sat Jun 25 01:43:43 UTC 2005

> At 12:50 PM 6/24/2005, Joseph S D Yao wrote:
> >On Fri, Jun 24, 2005 at 12:40:34PM -0400, Vinny Abello wrote:
> >...
> > > Do not use a CNAME for the record type as I've seen it cause some
> > > weird issues for the domain in general when people do this.
> >...
> >
> >A little more than this: it's explicitly forbidden, and only succeeds
> >because some name servers [including earlier versions of BIND] were
> >sloppy about accepting contradictory directives.
> >
> >If you put in a CNAME record for your zone, you are saying that you are
> >NOT authoritative for this zone, that you have NO information for this
> >zone, go see the canonical name (the right-hand name) for all of the
> >information you want.  Obviously NOT something you want to say about the
> >name of a zone that you are serving.  ;-)  Especially if the canonical
> >name is within that zone!  Can you say information black hole?
> <G> I thought it was forbidden, but I couldn't remember specifically 
> or had any references to do so offhand. I just know never to do it. :)

	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.

> Vinny Abello
> Network Engineer
> Server Management
> vinny at
> (973)300-9211 x 125
> (973)940-6125 (Direct)
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> Tellurian Networks - The Ultimate Internet Connection
> "Courage is resistance to fear, mastery of fear - not absence of 
> fear" -- Mark Twain
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at

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