Are underscores no longer supported in Bind 9.4?

Mark Andrews Mark_Andrews at
Sun Mar 4 22:48:26 UTC 2007

> On 3/4/07, Danny Mayer <mayer at> wrote:
> > CNAME's point to hostnames and therefore must follow the same rules. Are
> > you asking about the label of the CNAME record? It should be the same as
> > it acts as a hostname for all purposes. If it doesn't complain then it's
> > probably a bug. I didn't see anything in any of the RFC's that makes
> > that explicit but it would make sense.
> Yeah, this appears to be a bug then.  Both parts of the CNAME can have
> an underscore and named-checkzone and named-compilezone have no
> problem at all with allowing it without warnings or errors.

	No.  Checking CNAME reached the point of diminishing returns.
	You have to check what the CNAME(s) (you can have a CNAME
	chain) points to then issue a error/warning.  This also has
	to be done post load as the target may not yet be loaded.
	CNAME records can also point out of zone.

	Also people use the lack of CNAME checks to aid in "fixing"
	the zone.  They fix the offend name and add a CNAME at the
	old name to keep all their broken names working.

	One day we might add CNAME owername checks.  It's not a high
	priority however.


> -Jake
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at

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