Subject: Re: QType: ADDR

From: "Eric A. Hall" <[email-masked]>
Date: Thu, 08 Aug 2002 14:35:03 -0500

on 8/8/2002 2:07 PM Ted Lemon wrote:

> Unless I've just been off in space-cadet land, you've been saying that
> storing application keys in the DNS is wrong, because it means that a
> query of type ANY will no longer be possible for names with lots of
> keys.

That was one reason cited against willy-nilly RRs (specifically in
response to "other protocol data" and not to keys, but I didn't make that
clear, so fair play). Lots of RRs force retries for applications that do
qtype=any, there are plenty of deployed apps that do qtype=any (popular
apps anyway), and there will probably be a lot more of them. I'm not
advocating these apps, I'm using them as an example of harm caused from
excessive RRs.

FWIW, hotmail.com overflows even if you only ask for MX and get a full
answer (including all NS and glue). Mark mentioned excess PTRs as a source
of TCP overflow problems. So too many of one RR causes problems even for
applications that do the "right" thing. [Lord, please don't let this turn
into another strawman of me being against MX!]

There are other reasons, already mentioned. My opinion should be obvious,
that we need to be really conservative with this stuff. Even my dual-mode
i18n DNS work focuses on collapsing names into a canonical form for
storage, and avoids 2x storage and queries wherever possible.

Frankly, I am more concerned with large uses. A billion phones looking for
a billion phone numbers in the DNS is not going to be healthy. People talk
about storing user data in the DNS from time to time, as if defining and
replicating user-specific ACLs for RRs is no big deal. People talk about
having DNS be a PKI, with all that it implies.

The small stuff adds up too, you know.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/

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---

From: Markku Savela <[email-masked]>
Date: Thu, 8 Aug 2002 23:05:10 +0300

> From: "Eric A. Hall" <[email-masked]>

> a billion phone numbers in the DNS is not going to be healthy.

Yes, phones will ask AAAA and/or A.

Please, raise hand if *anyone* knows dual IPv4+IPv6 implementation
which actually chose to do qtype=ANY instead of specific A and AAAA?

I'm surprised (horrified) if I see any hands! :-)