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[ietf-clear] Re: Make CSV backwards compatible with legacy SPF records?

2004-12-08 23:57:41
On 12/1/2004 11:57 PM, wayne sent forth electrons to convey:

The point is that SPF has had, for a *very* long time, the checking of
the HELO domain. 
 

Small clarification: Certainly, I never thought that was my idea.
All I meant to claim was that the idea of using SPF records as a proxy 
for CSV records.

I. Surely, you understand that the SPF record discovery algorithm is
inherently less efficient/more costly than CSV's.  That's obvious, no?
How many DNS queries does it take to resolve elvey.com's SPF record to
a list of IPs?  A dozen or so?
   


For the purposes of HELO checking, the question is how many DNS
lookups does it take to resolve the SPF record for whatever HELO
domain you use, not elvey.com.  In most cases, this will be "v=spf1 a -all",
 

No it won't.  "v=spf1 a mx ptr -all" is most popular, based on stats you 
provided*.

How many DNS queries does it take to resolve to a list of IPs, on average? 
Seven?

A better but harder to answer question is: How many DNS
lookups does it take to resolve an SPF record, on average.

and that will require two DNS queries.  Yes, it is not optimal, but we
are about a year too late to change it in SPF now.
 

*http://www.imc.org/ietf-mxcomp/mail-archive/msg00644.html