Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!mips!twg.com!david
From: david@twg.com (David S. Herron)
Newsgroups: comp.mail.uucp
Subject: Re: rerouting to an absolute address
Message-ID: <7733@gollum.twg.com>
Date: 10 Aug 90 21:32:14 GMT
References: <1990Aug6.230109.4220@ibmpa> <1990Aug7.081953.6108@terminator.cc.umich.edu> <1990Aug7.134658.23389@Octopus.COM>
Reply-To: david@twg.com (David S. Herron)
Organization: The Wollongong Group, Palo Alto, CA
Lines: 52

In article <1990Aug7.134658.23389@Octopus.COM> pete@octopus.COM (Pete Holzmann) writes:
>Peter Honeyman writes:
>>Steve DeJarnett writes:
>>>From: steve@qe2.paloalto.ibm.com (Steve DeJarnett)

[A cast of thousands arguing about apple.sgi.com]

>>your name server must recognize the names that you make, or people and
>>other mailers that comprehend the domain name system are going to be very
>>very very very upset with you.
...
>I always thought that turning foo.com into an officially registered domain
>meant that it is up to foo.com to define what anything.else.foo.com means,
>including whether or not it is a valid address.
>
>If foo.com is not directly connected to the Internet, then it cannot answer
>any queries regarding anything.else.foo.com. peter, are you saying that
>this is a vvvvv wrong use of domains?

Simple..

For disconnected domains you have the nameserver advertise a wild-card
MX record .. in your example it would be

*.foo.com.	IN	MX	0	relay.some.place
*.foo.com.	IN	MX	10	relay-2.some.place

Mailers are supposed to, when trying to deliver mail, rummage about
looking for MX records before doing anything else.  (er.. ah.. make
that: rummage about after MX records *after* rooting out any CNAME
records.)

	[ Side bar: MX == Mail eXchanger, the place to which the mail
		should be sent.  This is a prioritized list.
		    CNAME == Canonical NAME, gives the real name for
		a particular name to support aliasing.]

A wild card like the above will make the answering nameserver generate
a valid-looking response for any name you happen to toss at it.  Even
if the name is wrong.

This has a small side effect that incorrectly address mail will have to
travel to your site before being actually verified.  This might be
expensive or not depending on how often this happens.


As usual, nameservers solve every problem known to man :-)
-- 
<- David Herron, an MMDF weenie, <david@twg.com>
<- Formerly: David Herron -- NonResident E-Mail Hack <david@ms.uky.edu>
<-
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