Eliminating the "www" Portion of a URL
Barry Margolin
barmar at bbnplanet.com
Tue Mar 14 17:11:10 UTC 2000
In article <200003141653.KAA20332 at achilles.ctd.anl.gov>,
Barry Finkel <b19141 at achilles.ctd.anl.gov> wrote:
>Cricket replied:
>>I imagine there are still some misguided mailers out there that use
>>the address record for a domain name instead of the MX records
>>to determine where to deliver the mail.
>
>Last week I worked on a mail problem with a Macintosh-based mailer.
>When it tried to send mail to
>
> aaa.bbb.ccc.com
>
>and it did not find an MX record for the full name, it did NOT look for
>an "A" record; it then looked for an MX record for the sub-domain
>
> bbb.ccc.com
That's the parent domain, not a sub-domain.
>and in our case, that MX record pointed to a different mail host than
>the "aaa" node, where the recipient's mailbox resides. Once I added
>an MX record for aaa that pointed to itself, mail from this Mac mailer
>was deliverable.
That mailer is totally broken. Nothing in the Internet standards suggests
this behavior, and they specifically say that the A record for
aaa.bbb.ccc.com should be used if there's no MX record. The MX record is
used as a way of redirecting mail away from the host; the "normal" action
is to send the mail to the host specified in the email address.
I could understand this behavior as a fallback if aaa doesn't have an MX
record or A record. However, if that's the behavior that the destination
site really wanted, they could easily have installed a wildcard MX record
(basically, the sending mailer would be pretending that the bbb.ccc.com MX
record is also a wildcard MX record).
--
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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