Douglas Otis wrote:
To that end:
Obsoleting the A record discovery process will establish one location
for _any_ email related policy record, and not just that for DKIM.
If I understand you, this isn't working to work Doug. A records are
required.
Are you familiar with the MX lookup and expansion process?
In case you didn't, the MX query does not always result in IP
addresses. The IP addresses are obtained in A lookups of the host names
by provided by the MX records.
In other words, not all MX query gives you IP addresses to try.
A good example is YAHOO.COM:
C:\> nslookup -query=A yahoo.com
Non-authoritative answer:
yahoo.com MX preference = 1, mail exchanger = f.mx.mail.yahoo.com
yahoo.com MX preference = 1, mail exchanger = g.mx.mail.yahoo.com
yahoo.com MX preference = 1, mail exchanger = a.mx.mail.yahoo.com
yahoo.com MX preference = 1, mail exchanger = b.mx.mail.yahoo.com
yahoo.com MX preference = 1, mail exchanger = c.mx.mail.yahoo.com
yahoo.com MX preference = 1, mail exchanger = d.mx.mail.yahoo.com
yahoo.com MX preference = 1, mail exchanger = e.mx.mail.yahoo.com
Now you expand each of these:
C:\> nslookup -query=A f.mx.mail.yahoo.com
Non-authoritative answer:
Name: f.mx.mail.yahoo.com
Addresses: 209.191.88.247, 68.142.202.247
and you do this for EACH the MX host records to finally get a total
expanded list of IP addresses.
--
Sincerely
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com
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