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

[Matus UHLAR - fantomas]

> > 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".

> In article <glnemv$10nf$1 at sf1.isc.org>,
>  Matus UHLAR - fantomas <uhlar at fantomas.sk> wrote:
> > 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.

On 27.01.09 23:51, Barry Margolin wrote:
> So what?  If the IP isn't in the additional section, the client will do 
> its own A query.

so the client has to do an A query, because A is not returned in the MX
query.

> There's no requirement that the response to the MX record include the A 
> record.  It's nice if it does, since it saves a query, but this is just 
> an optimization.

exactly. That's what I was trying to explain.
-- 
Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
Windows 2000: 640 MB ought to be enough for anybody