"wayne" <wayne(_at_)midwestcs(_dot_)com> wrote:
"Hallam-Baker, Phillip" <pbaker(_at_)verisign(_dot_)com> writes:
In effect what you are saying here is that SPF is going to be so
important
that it can in effect claim TXT for exclusive use.
Just those with the magic string at the beginning that says "v=spf1 ".
Imagine that a domain has four TXT RRs, one of those if spf (for example
altavista.com). Your client needs to query the 4 TXT RRs for that domain,
compare the first chars of each record to "v=spf1 " and decide which one, if
any, is the spf record.
With the change that Phillip is proposing, the client would only need to
query the _spf subdomain (i.e. _spf.altavista.com), if you recieve
something, you know that you have a SPF record and you can parse it.
From a design point of view, this is much cleaner, and from a practical
point of view, if we multiply that that several billion emails a day and you
start to see a big difference in ressources saving.
It's pretty obvious to me that this is a better way of doing things, what
I'm not totally convinced of is that is a big enough of a problem to change
the specification.
There are other systems that co-opt TXT records and most of them use a
magic string also. It is incumbent on those systems that overload the
use of the TXT record to make sure that they don't conflict with past
or future usage, and I think SPF accomplishes that just fine with the
version string.
It's reasonnable to hope that there won't be conflicts with future protocols
by using the magic string, but more CPU and bandwidth will be used than with
Phillip's proposal.
Regards,
GFK's
--
Guillaume Filion, ing. jr
Logidac Tech., Beaumont, Québec, Canada - http://logidac.com/
PGP Key and more: http://guillaume.filion.org/
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