Re: [Sheflug] * on mail exchanger records

[Dave Mitchell <nospam [at] fdgroup.co.uk>]

> I'm having something of an argument with my ISP over their dns setup (naming
> no names :). Basically, the source of my frustration is their inclusion of
> 
> 	* 	IN MX [their mail servers]
> 
> in all of the domains for which they are authoratitive (my company's
> included!). Which isn't necessarily a problem, in and of itself. However..
> with domain/search set in the resolv.conf, this throws up an interesting
> problem.

First off, its isn't quite as bad as you think - the only thing it will
affect is mail servers - lynx and the like will be looking for A (address)
records rather than MXes, so they wont be affected.

Second, most modern resolvers have a rule along the lines of: if the
domain you're seaching for has at least 1 dot in it, look it up first
*without* appending the default domain, and only if is is not found proceed
through the usual search algorithm. This behaviour was specifially added
to help ameliorate problems with wildcards.

So, things *may* be okay.
However, I'd say the ISP are still in the wrong - unless there is a specific
need to capture all emails to foo [at] anything.domain.com, dont have the wildcards:
It's only a source of potential confusion and error.

The only advantage it has is that if emails from you get to the outside
world with a from address that hasn't had the hostname stripped out
(ie foo [at] mymachine.domain.com), then people can still reply. However,
the trick there is to fix the mail server  so that such addresses dont
leak out in the first place !!

So, tell your ISP to go take a hike, or to at least give a decent technical
justication for their actions :-)


* Dave Mitchell, Senior Technical Consultant
* Fretwell-Downing Informatics Ltd, UK.  Dave.Mitchell [at] fdgroup.com
* Tel: +44 114 281 6113.                The usual disclaimers....
*
* Standards (n). Battle insignia or tribal totems

print+qq&$}$"$/$s$,$*${$}$g$s$@$.$q$,$:$.$q$^$,$@$*$~$;$.$q$m&if+map{m,^\d{0\,},
,${$::{$'}}=chr($"+=$&||1)}q&10m22,42}6:17*2~2.3 [at] 3;^2$g3q/s"&=~m*\d\*.*g


---------------------------------------------------------------------
Sheffield Linux User's Group - http://www.sheflug.co.uk
To unsubscribe from this list send mail to
- <sheflug-request [at] vuw.ac.nz> - with the word 
 "unsubscribe" in the body of the message. 

  GNU the choice of a complete generation.