Subject: Re: Little endians, big endians, and 16 bit eggs

From: "Anders Rundgren" <[email-masked]>
Date: Sat, 22 Jan 2005 17:59:36 +0100

>John L wrote:
>True, but if you're using prefixes, regardless of what record types
>you're (re)using, you need some sort of registry if you want to be
>sure that nobody else will use your prefix to mean something else.  I
>suppose you could use the URI trick to get uniqueness from domain
>names, but I have my doubts about how 

URI are used in numerous other contexts so the only trick is to
agree on a URI-to-DNS-label-translator

>The issue of how hard it is to get something into the registry is a
>separate question from what it is you're registering.  I agree that in
>retrospect it should have been easier to register new RR types so that
>people wouldn't have written DNS software that assumes the set of RR
>types is forever fixed.

Looking at W2KS DNS GUI server I don't agree.  I only supports a limited
set of types.  And since most people actually only need a text-something
it makes no sense to create a new text-something over and over again.

The URI-suffix (not prefix) covers all readonable needs. And it costs
nothing to implement or support either.

Anders

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---

From: "John R Levine" <[email-masked]>
Date: 22 Jan 2005 12:37:40 -0500

> agree on a URI-to-DNS-label-translator

Ahem, to finish my sentence, how likely it is that people will configure
long hard to type names into their DNS zones.  I realize URI based labels
are common in XML, but there's a lot more people updating DNS zones by
hand than writing XML files by hand.

> it makes no sense to create a new text-something over and over again.

Actually, it's been a long time since I've seen a type that should be a
text something.  TXT records are just the ticket for unstructured textual
data, which few applications use.  SPF records, for example, are a highly
structured list of operators and typed operands, with the operand types
including DNS names, IP addresses, CIDR ranges, macros that expand to DNS
names, and probably a few other things I've forgotten.  Every DNS client
that uses SPF has to parse the text up into the operators and operands,
and one of the many unanswered questions about SPF is how robust the
parsers are in the face of accidentally or deliberately invalid data.

If I were doing something like SPF, I'd want a record type that was a list
of operator/operand pairs with the operators probably being a single byte,
and the operands being in an appropriate native coding, e.g. five binary
bytes for an IPv4 CIDR and a list of null-terminated strings for a DNS
name.  That both avoids the application level parser and forces some
degree of validation as the data goes into the record.

Regards,
John Levine, [email-masked], Primary Perpetrator of "The Internet for Dummies",
Information Superhighwayman wanna-be, http://iecc.com/johnl, Mayor
"I dropped the toothpaste", said Tom, crestfallenly.