Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!CS.NIU.EDU!rickert
From: rickert@CS.NIU.EDU ("Neil Rickert, N Illinois U, CS")
Newsgroups: comp.protocols.tcp-ip.domains
Subject: Re: Proposed extensions to MX records.
Message-ID: <9103301612.AA16080@mp.cs.niu.edu>
Date: 30 Mar 91 16:12:14 GMT
References: <1991Mar28.182232.13467@agate.berkeley.edu>
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: inet
Organization: The Internet
Lines: 41

>This proposal implies using Domain Names for routing decisions.  It's always
>been my understanding that a DNS name implies nothing at all about routing
>(for IP or mail or anything else).  Is this no longer true?
>
>For example, if all parties agree, and everyone sets up the name servers
>properly, ABC.SomeU.EDU might appear on the net 128.32 here at UC Berkeley
>instead of on net N.N which is physically at Some U.
>
>In other words the DNS name implies nothing about topology (as I
>understand it). 

 I gave two examples in my original message.  The first dealt with mailing to
the AU domain, and the second to an organizational domain I call FOO.BAR.

 As I admitted in a later response, the first example is a slight stretch, and
in any case the problems cited will be solved with improved technology.

 The main importance, as I see it, refers to the second example.  This is the
case where an organizational domain decides, for reasons of its own policy,
to control access to the net by limiting packet forwarding and by requiring
that email go through a few gateway hosts.  Organizations which do this
include private corporations and educational institutions.  Regardless of
whether we agree or disagree with these policy decisions, they exist.  Since
they are based on policy, they will not quick change with improved connectivity.

 Whether or not the domain names reflect the packet routing in general, they
heavily effect mail forwarding based on these policy decisions.

 Organizational domains which follow this practice are already using ad-hoc
approaches to change the way some MX records are processed.  But often these
ad hoc approaches are deleterious to the net as a whole.  The proposal is
designed to provide a consistent way of handling the problem.

 One alternative that is sometimes used is to set up alternative sets of
DNS records, so that the domain database looks different from inside the
organizational domain.  Sometimes this even involves alternate root name
servers.  When this approach is used there is a risk that a minor error can
inject bogus DNS records into the Internet nameservers.  I would much prefer
a workable approach which does not entail such a risk.

 -Neil Rickert