Re: DNS goofups galore...

From: Michael H. Warfield (
Date: Thu Feb 08 2001 - 18:32:32 EST

On Thu, Feb 08, 2001 at 02:58:30PM -0800, H. Peter Anvin wrote:
> Followup to: <>
> By author: Gerhard Mack <>
> In newsgroup:
> >
> > 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
> --
> <> at work, <> in private!
> "Unix gives you enough rope to shoot yourself in the foot."


 Michael H. Warfield    |  (770) 985-6132   |
  (The Mad Wizard)      |  (678) 463-0932   |
  NIC whois:  MHW9      |  An optimist believes we live in the best of all
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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:13 EST