Subject: draft-ietf-dnsext-apl-rr-01.txt

From: Thomas Narten <[email-masked]>
Date: Wed, 16 Aug 2000 11:54:44 -0400

The IESG discussed this ID recently and a meta issue was discussed
that I think the WG should think about. In particular:

>    The specification of particular application scenarios is out of the
>    scope of this document.

I.e, this ID defines an RR for which no usage has been specified, and
for which in the future, multiple incompatable usages might be
specified.

It seems to me that the semantics of an RR should be well-defined and
uniformly interpreted by clients. If they are not, one runs the risk
that different clients will query for the same RR (but for different
reasons) and get unexpected results. This is particularly true if two
logically different uses make use of the same RR. An administrator
might define RRs with one usage in mind, but those RRs are then also
queried by other applications that interpret the meaning of that RR
differently than intended by the owner. Wrong things can happen as a
result. Thus, even in cases where the raw format of an RR might be
correct for multiple different uses, it might be better to define
multiple different RRs each having the same syntax, but (possibly)
different semantics and (possibly) different uses.

I note that semantics/usage of the Negation Flag is explicitely not
defined in this document, so the RR seems underspecified.

As an example, consider TXT records. You can put lots of things in
them, but many consider it bad form to do so precisely because the TXT
RR one gets back may have nothing to do with the usage the client is
expecting.

To summarize, I wonder if:

1) This document should be published at all, without a specific usage
   associated with it for the reasons discussed above.

2) Even if the document is published, making it a PS seems wrong,
   without a specific usage documented along with it that clearly
   defines the semantics and intended usage.

What does the WG think about this?   

Minor comments:

> 4. APL RDATA format
> 
>    The RDATA section consists of zero or more strings (<apstring>) of
>    the form

Is the "string" description correct? The RDATA actually consists if
fixed length fields such as a prefix, a bit, etc.

>   ftp://ftp.iana.org/in-notes/iana/assignments/address-family-numbers.

The IANA requests that all references to numbers be via:

http://www.iana.org/numbers.html

Thomas

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