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Re: current usage of AAAA implicit MX?

2008-04-04 15:06:03

At 10:27 -0700 on 04/04/2008, Dave Crocker wrote about Re: current usage of AAAA implicit MX?:

ps. While surveys are always useful, I'll repeat the observation that changing the query model for SMTP is out of scope. The current model is 1) look for MX, 2) look for address record (A and/or AAAA). Anything that removes step 2 is a model change.

What is being talked about is NOT removing Step 2 but restricting it to looking at A records. Looking at AAAA records in Step 2 should not be allowed since due to the ability to use an MX record to point at an IPv6 MTA, there is NO NEED (unlike the IPv4 case due to historical support for locating an IPv4 MTS directly by its A record) to EVER expect that an IPv6 MTA should/can be DIRECTLY locatable via its AAAA record.

Even RFC 3974 talks ONLY about the use of MX records to locate IPv6 MTAs.