e: BIND 9.6 Flaw - CNAME vs. A Record in MX Records are NOT "Illegal"

[bsfinkel at anl.gov]

Al Stu" <Al_Stu at Verizon.net> wrote:

>How about these two?
>
>> nullmx.domainmanager.com
>Non-authoritative answer:
>Name:    mta.dewile.net
>Address:  69.59.189.80
>Aliases:  nullmx.domainmanager.com
>
>> smtp.secureserver.net
>Non-authoritative answer:
>Name:    smtp.where.secureserver.net
>Address:  208.109.80.149
>Aliases:  smtp.secureserver.net
>
>There are two reasons it does not blow up in peoples face.  1) If it is in 
>the CNAME RR points to an A record in the same zone, both the A record and 
>the CNAME record are returned, thus meeting the A record requirement.  2) 
>SMTP servers are required to accept an alias and look it up.  Thus there is 
>no need for this.
>
>And no it does not matter if there are multiple MX records with different 
>preferences values.

You say, "both the A record and the CNAME record are returned."
We know that BIND does this.  Is this part of the RFC?  Do other DNS
implementation return both the "A" and the CNAME?
----------------------------------------------------------------------
Barry S. Finkel
Computing and Information Systems Division
Argonne National Laboratory          Phone:    +1 (630) 252-7277
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