Re: DNS goofups galore...

["Michael H. Warfield" <mhw@wittsend.com>]

On Thu, Feb 08, 2001 at 02:58:30PM -0800, H. Peter Anvin wrote:
> Followup to:  <Pine.LNX.4.10.10102081346001.16513-100000@innerfire.net>
> By author:    Gerhard Mack <gmack@innerfire.net>
> In newsgroup: linux.dev.kernel
> >
> > Thanklfully bind 9 barfs if you even try this sort of thing.
> > 

> Personally I find it puzzling what's wrong with MX -> CNAME at all; it
> seems like a useful setup without the pitfalls that either NS -> CNAME
> or CNAME -> CNAME can cause (NS -> CNAME can trivially result in
> irreducible situations; CNAME -> CNAME would require a link maximum
> count which could result in obscure breakage.)

	It generally forces another DNS lookup.  If you do a resolve on
a name of type=ANY it returns any MX records and A records.  If you then
do a resolve on the MX records, you then get a CNAME and then have to
add an additional lookup for the CNAME.  If you have a lot of MX records
and not all the servers are "up" that can add up to a significant
increase in DNS traffic.

> 	-hpa
> -- 
> <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
> "Unix gives you enough rope to shoot yourself in the foot."
> http://www.zytor.com/~hpa/puzzle.txt

	Mike
-- 
 Michael H. Warfield    |  (770) 985-6132   |  mhw@WittsEnd.com
  (The Mad Wizard)      |  (678) 463-0932   |  http://www.wittsend.com/mhw/
  NIC whois:  MHW9      |  An optimist believes we live in the best of all
 PGP Key: 0xDF1DD471    |  possible worlds.  A pessimist is sure of it!

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