"David MacQuigg" persisted:
<snip>
Anyway, back to the question of including an IP address as "additional
information" in the SPF query. This doesn't require a new record type, and
certainly no new "infrastructure". Is anyone aware of any specific
prohibition on doing this? Is there a problem with existing DNS servers
not being able to ignore unexpected "additional informtion"?
The "Additional Information" section in DNS messages is, according to RFC1035,
used only for responses. The obsolete RFC884 has some examples of it being used
in association with _special_ queries (not any that are used by SPF). I cannot
find any query type in RFC1035 for which the "Additional Info" field is not
_required_ to be <empty> while the query is being transmitted to the server.
Of course, there are a further 19 RFCs which update RFC1035, which I have not
studied. If you can show us a use of "Additional Information" somewhere in one
of those, then I guess you will have made your point.
From a more pragmatic standpoint, I would be amazed if any of the standard
software suites (bind, etc.) expect to find an "Additional Information" section
in an inbound query, or would be able to do anything with it if it were present.
Nor, I hazard, would any standard clients be prepared to send it for you.
Chris Haynes