spf-discuss
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RE: New DNS record issue.

2004-01-13 08:15:35
In 
<2A1D4C86842EE14CA9BC80474919782E011132E1(_at_)mou1wnexm02(_dot_)vcorp(_dot_)ad
.vrsn.com> "Hallam-Baker, Phillip" <pbaker(_at_)verisign(_dot_)com> writes:

_spf.aol.com.                255     IN      TXT     "[...]

This was actually what was originally proposed, but it received a lot
of resistance.  Meng moved the TXT record after it became clear that
most SPF publishers would not be using a in-addr.arpa/DNSBL type tree
to list the servers that are authorized.  Originally, this tree was
hard coded into that domain name.

I do not understand the issue you are raising here. There is a big
difference between the tree idea and the issue of a namespace prefix.

The big advantage to using the prefix is that the service can tell with a
single request whether a service does SPF or not, there is no need to do any
further parsing at all.

That is a huge advantage if you have a scripting type scheme, you can have
code of the form:

spf = Get_SPF_Record (domain)
if (spf != null) then
        Do_SPF_Processing (message, spf)

Otherwise you have to start looking at the content of the record which is a
bit more complex.

Maybe Meng can address the reasons for the change more clearly, but as
far as I'm concerned, this isn't a major issue and breaking backward
compatibility at this point in time would not be a good idea.

My experience of the Web is that every time this argument was raised it came
back and bit us.

It took over 5 years to even partially fix the broken BASIC authentication
scheme after it escaped the lab. 

Deployment of SPF is negligible compared to where it is going to be if
successful. If we changed the spec today, advised everyone to double up the
records in the interim and told new filter writers to use the _spf prefix we
would be finished with the transition within about six months.


The biggest block to adoption is uncertainty. The principle problem with TXT
records is the temproary stigma attached to them. If you use the raw TXT
record people will always be asking when you are going to get a proper RR
assigned.

As I keep exlaining to Meng, I am probably the person in the group who best
understands what he is asking of his knight on a charger. Unfortunately it
is a fools errand, should not be that way, but that is what we are up
against.


                Phill

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