At 7:14 PM -0400 8/9/04, Meng Weng Wong wrote:
While such a change is, from the standpoint of architectural
purity, absolutely the correct thing to do, I fear that in
practice it may lead to confusion, needless duplication of
records, and a failure to achieve the intended objective.
In other words, it is my opinion that engineering
considerations do not weigh in favour of changing the string.
I particularly do not want to see a world where the norm is:
example.com TXT "v=spf1 a mx ptr"
example.com TXT "v=spf2 a mx ptr"
Both records would contain the same content, yet senders
might feel the need to publish both "just to be on the safe side".
Both records do _not_ contain the same information. The first
record has a target of MAIL_FROM; the second has a target
of PRA. The fact that the strings "a mx ptr" happen to be
the same in both records does not change that fundamental
fact. The fact that the same IPv4 dotted quad might appear in
an MX record and NS record for example.com doesn't change
the fact that the records tell you different things about how
that domain's systems are set up. The situation here is
parallel; it isn't as obvious because you're using the overloaded
TXT record rather than the new RR.
As an aside, this is one of the practical reasons why subtyping
the TXT record is a bad idea; it gets very easy to confuse the types,
even for folks who have been working with it for a long time.
regards,
Ted Hardie