MX records

Mark_Andrews at isc.org Mark_Andrews at isc.org
Fri Mar 15 21:43:10 UTC 2002


> 
> I've got a question about MX records.  My domain, twu.edu, has a mail server
> which has an A record which points to just the domain name like so:
> @	IN	A 	205.165.49.231
> It is also the preferred mail server:
> @	IN	MX	0 venus.twu.edu
> And of course it also has its own A record:
> venus	IN	A	205.165.49.232
> 
> There are also some other mail servers with lower preference values:
> @	IN	MX	10 exchange.twu.edu
> @	IN	MX	20 vulcan.twu.edu
> etc.
> 
> Now, as I understand MX records, mail sent to somebody at twu.edu should try
> venus first, then exchange, then vulcan.  However, if somebody at twu.edu has
> their account on exchange or vulcan, the mail never gets there.  If I send
> it to somebody at exchange.twu.edu or somebody at vulcan.twu.edu it gets there.
> Why isn't this working?  Is it because of this record: @	IN	A
> 205.165.49.231?  It seems to be that since twu.edu points to a particular
> IP, mailers are just looking it up directly and not even looking for the MX
> records.  Thanks in advance for any help.
> Ted Wood
> 

	I think you have the wrong idea about MX records.  If
	venus.twu.edu says that somebody at twu.edu doesn't exist
	then the other MX's are *not* tried.  It's up to you
	to ensure that all the MX for twu.edu accept mail for
	all possible users and arrange delivery locally.

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org


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