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

[Al Stu]

"They are two queries. If mx1 would be an A, it would be returned in the 
first query. Since it's a CNAME, the IP is not returned in the MX query."

So.  RFC 5321 5.1, Locating the Target Host, says the CNAME is to be 
processed.

"The lookup first attempts to locate an MX record associated with the name. 
If a CNAME record is found, the resulting name is processed as if it were 
the initial name."


*** PLEASE don't copy me on replies, I'll read them in the group ***


----- Original Message ----- 
From: "Matus UHLAR - fantomas" <uhlar at fantomas.sk>
To: <bind-users at lists.isc.org>
Sent: Tuesday, January 27, 2009 9:01 AM
Subject: Re: BIND 9.6 Flaw - CNAME vs. A Record in MX Records are NOT 
"Illegal"


> On 27.01.09 08:46, Al Stu wrote:
>> So then you disagree that the following example returns a valid address
>> record for srv1?
>>
>> srv1  300 IN A 1.2.3.4
>> mx1   300 IN CNAME srv1.xyz.com.
>> @   300 IN MX 1 mx1.xyz.com.
>>
>> 1) Select Target Host:
>> The MX query for xyz.com delivers mx1.xyz.com which is a CNAME.
>>
>> 2) Get Target Host Address:
>> The A query for mx1.xyz.com delivers the address (A) record of
>> srv1.xyz.com, 1.2.3.4, and also delivers the alias (CNAME) record of
>> "mx1.xyz.com".
>
> They are two queries. If mx1 would be an A, it would be returned in the
> first query. Since it's a CNAME, the IP is not returned in the MX query.
>
> -- 
> Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
> Warning: I wish NOT to receive e-mail advertising to this address.
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> It's now safe to throw off your computer.
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