TXT records and what not to use them for

[Thomas Narten <narten@raleigh.ibm.com>]

Jerry Scharf <scharf@vix.com> writes:

> I think this kind of information is best done in TXT records. The format
> is arbitrary (what are the rules from country to country for the form and
> meaning) and it still requires that you look up some external database
> and covert it to lat and lon to display on the map. IMO, with the external
> lookup, this looks like it belongs in other places besides DNS.

General question: my sense has been that putting stuff in TXT records
is OK if the intent is for humans to read it.

It is much more dubious to put stuff into TXT records when the
intention is to have programs parse them and extract
information. Reasons include:

1) strange things happen since TXT records can contain anything --
folks will start looking for them expecting them to contain certain
info...

2) Success would not necessarily be a good thing. If widescale
deployment takes place, things get more out of hand. Especially if
multiple different uses become popular. I.e, the point of having
different RR types is so that you get exactly the info you want, not a
bunch of extra stuff you have to filter out.

3) The main reason folks want to use TXT reasons is that they are easy
to deploy (i.e., deployed nameservers support them). Seems to me that
name servers could also be designed to allow the definition of
arbitrary RR formats (i.e, by having a simple langauge for describing
the format of new RRs). Heck, even allowing a binary format would work
-- one could have preprocessing tools that take a human readable
definition of RR contents and translate them into a generic format the
nameserver could input.  Folks could then create new RR types and
deploy them without requiring new nameserver software
implementations. This would make it simpler to experiment with new RR
types, which wouldn't be a bad thing.

Finally, last I checked, RR types were 16 bits long, and we've used
only a miniscule fraction of them. I don't think we need to be
particularly conservative in their usage. We should encourage use
where appropriate.

Thomas