Parent is a CNAME

Barry Margolin barmar at
Wed Dec 2 17:52:01 UTC 2009

In article <mailman.1165.1259775639.14796.bind-users at>,
 Joseph S D Yao <jsdy at> wrote:

> On Wed, Dec 02, 2009 at 12:47:08PM +0000, Sam Wilson wrote:
> > In article <mailman.1153.1259725836.14796.bind-users at>,
> >  Joseph S D Yao <jsdy at> wrote:
> [incorrectly]
> > > No.
> ...
> > Not true.  CNAME chains - CNAMEs pointing to other CNAMEs - are 
> > inefficient and discouraged but the DNS spec is built to ensure that 
> > they work.  Check out sometime (or and 
> > wonder at how many people would be annoyed if they didn't.
> CNAME chains have nothing to do with this.  THIS is perfectly legal:
> a	CNAME	b
> b	CNAME	c
> c	CNAME	d
> d	CNAME	extra-ordinary

I think he misunderstood you to be saying that the name that has a CNAME 
can never appear on the *righthand* side of a RR.  This is true for 
records like MX and NS -- they mustn't point to aliases.  CNAME chains 
are the exception to this rule.

Barry Margolin, barmar at
Arlington, MA
*** PLEASE don't copy me on replies, I'll read them in the group ***

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