April Lorenzen responds:
adsl-101-33.pool-217-45.user.mxout.bbc.co.uk - in my opinion, nothing
should intercede between .mxout. and the domain name which is one level
beyond the TLD, (or SLDs like co.uk which delegate authority to the
third level.)
Frank - I appreciate your new mapping of 127.0.0.x and I believe mine
should be changed to something along the lines of yours, after others
have time to respond and comment.
Addressing comments from others - I think the most useful purpose for
.mxout. is for rejecting mail from IPs where the rDNS doesn't include
.mxout.example.com, and where example.com has declared that the only IPs
authorized to operate a mail server on its networks, will have
.mxout.example.com. ( 247.200.9.68.zombie.example.com vs
247.200.9.68.mxout.example.com)
As I see it, .mxout. has limited usefulness for any other purpose and
wasn't intended by me to compete with SPF or other designated sender
proposals.
- April
Message-ID: <40A57EA5(_dot_)322C(_at_)xyzzy(_dot_)claranet(_dot_)de>
Date: Sat, 15 May 2004 04:21:25 +0200
From: Frank Ellermann <nobody(_at_)xyzzy(_dot_)claranet(_dot_)de>
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To: ietf-mxcomp(_at_)imc(_dot_)org
Subject: Re: 7. BCP. Proposal... dynamic-address-specific rDNS
References: <20040514051252(_dot_)GA3400(_at_)m450>
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Yakov Shafranovich wrote in <asrg.ietf.org>:
> Take a look at the following:
> http://www.ietf.org/internet-drafts/draft-lorenzen-marid-mxout-00.txt
That's a good idea. Some quick observations:
127.0.0.7 combines 127.0.0.4 and 127.0.0.6
127.0,0.5 combines 127.0.0.4 and 127.0.0.3
I'd prefer the usual 2, 4, 8, etc. approach, where 6 is the
combination of 2 and 4, etc. The 127.0.0.1 class might be
useless, and even if that's wrong I don't like any meaning
for 127.0.0.1 (except from localhost of course... ;-)
Here's another scheme:
old 127.0.0.1 new n/a
old 127.0.0.2 new 127.0.0.2
old 127.0.0.3 new 127.0.0.6 (2 + 4)
old 127.0.0.4 new 127.0.0.10 (2 + 8)
old 127.0.0.5 new 127.0.0.14 (2 + 8 + 4)
old 127.0.0.6 new 127.0.0.18 (2 +16)
old 127.0.0.7 new 127.0.0.26 (2 + 8 +16)
The examples are clear for simple cases like example.com, but
less obvious for say adsl-101-33.pool-217-45.user.bbc.co.uk,
where should I look for the mxout, is it mxout.bbc.co.uk, or
mxout.user.bbc.co.uk, or some right to left strategy ?
Bye, Frank