Messages in this thread |  | | Date | Thu, 8 Feb 2001 18:32:32 -0500 | From | "Michael H. Warfield" <> | Subject | Re: DNS goofups galore... |
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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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