Important problem with MX *.

Chris Buxton cbuxton at menandmice.com
Fri Aug 25 16:56:29 UTC 2006


You can't do this with a wildcard record. A wildcard cannot appear in  
the data portion of a record. Therefore, your wildcard MX record  
would have to point to some particular mail server.

Also, a wildcard will not be used if another record (of any type) has  
the same name as the query name. Presumably, you have individual A  
records for the names you want this wildcard to match. This will not  
work.

However, there's some good news for you: The behavior you're looking  
for is actually the default built into the SMTP standard: If an MTA  
needs to deliver mail to a destination domain that has no MX record,  
the MTA should look for an address record (at least an A record, not  
sure if it would work with an AAAA record). If an address record  
exists, there is an implied MX record, like this:

target.domain.	0	IN	MX	0  target.domain.

So as long as mail servers follow the standard (which not all do  
100%, but I've never seen this rule completely disregarded by an  
MTA), you don't need to do anything.

Chris Buxton
Men & Mice

On Aug 24, 2006, at 9:10 AM, bg75000 at hotmail.fr wrote:

> English
> I have a problem with DNS Bind9. I would like to create a resource
> recording MX * :
> when the main server of names cannot solve a mail with the field  
> MX, it
>
> is necessary that this server returns by default its own IP  
> address. To
> resume,
> when the main server of names can solve, it solves, but when it cannot
> solves,
> instead of sending an error message, it sends its address IP.
> If you want more informations ask me.
> Thank you for your help and your answers.
>
> Français
> J'ai un problème avec DNS Bind9. Je voudrais créer un enregistrement
> MX * :
> lorsque le serveur de noms principal ne sait pas résoudre un mail avec
> le champ MX,
> il faut que ce serveur renvoie par défaut sa propre adresse IP. En
> résumé, lorsque le serveur principal
> sait résoudre,il résout, mais lorsqu'il ne sait pas résoudre, au
> lieu de d'envoyer un message d'erreur,
> il envoie son adresse IP. Si vous voulez plus d'informations,
> demandez-moi.
> Merci.
>
>
>



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