On 9/11/2014 3:47 AM, Matus UHLAR - fantomas wrote:
On 10.09.14 18:13, Kevin Darcy wrote:
No, what I'm saying is that if
example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then
where does 48.113.0.203.in-addr.arpa point?
Completely your decision.
Some people will point it at example.com, some will point it at
www.example.com. What you get is a mish-mosh. No consistency.
Do not mix multiple A and PTR. they are just different things.
You are creating issues where there are none.
On 11.09.14 11:20, Kevin Darcy wrote:
The issue is consistency. If you give admins choices where to point a
PTR, and the RFCs don't provide any clear guidance, you're going to
get inconsistent results.
sorry, but again - you are searching for consistency somewhere, where no
consistency (nor a PTR) is required.
Consistency is a good thing, isn't it? Sure, the earth isn't going to
fall off its axis of rotation just because of the way people point
their A and PTR records, CNAME or don't CNAME. But if we can nudge
people in the direction of consistency, and there is no downside, why
wouldn't we do that? That's what "best practices" are all about --
impelling people towards processes/methods/conventions that
ultimately benefit *everyone*. Greatest good for the greatest number,
and all that.
I haven't met a case where this level of "consistency" would be needed.
I have met a case where the "only one A should point to an IP" caused
troubles.
your argument fails immediately when there's need for more than just A on
www.example.com
(Yes, I'm aware that there was a proposal recently discussed on the
DNSOP list for an MX-target convention to denote "no mail service
offered here". That would presumably solve the problem I cited in the
previous paragraph. But AFAIK that proposal is many years away from
widespread adoption, and even if adopted, it puts an extra burden on
the DNS admins to populate the "no service" MX record, which, again,
is going to produce inconsistent results -- some admins will remember
to do it; many won't).
... and this is just example of it.
The same applies for all other RRs for exmaple.com Alan named crap.
Actually, the only other RR type that Alan enumerated specifically
was NS, which operates on entirely different principles, and serves a
significantly different function, than MX-based mail routing. Who
would be looking up www.example.com with QTYPE=NS? Is that even a
plausible use-case scenario?
well, me and Alan have shown examples why "www CNAME @" is not a good idea.
we both also said it's personal preference.
What other RR types do you have in mind?
Does it matter at all? It _may_ happen, and it's the case where CNAME is
not usable.
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
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safety deserve neither liberty nor safety. -- Benjamin Franklin, 1759
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