Chaining MX records illegal?

[Barry Margolin]

In article <dku9b6$20ih$1 at sf1.isc.org>,
 Chris De Young <chd at arizona.edu> wrote:

> Hi,
> Am I correct in my interpretation that chaining together MX records is 
> illegal,
> despite the fact that it seems to mostly work?
> 
> For example:
> 
> chud.net	mx 10	mail.foobar.com.
> .
> .
> .
> mail.foobar.com	mx 10	smtp.yahoo.com.
> 
> is a no-no?

There's nothing invalid about it, but it won't do what I think you 
expect it to do.  Mail for chud.net will be delivered to 
mail.foobar.com, not smtp.yahoo.com.  After looking up an MX record, the 
sending system will then look up the A record of the name it gets, it 
shouldn't look for an MX record of it.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***