Adding MX to an alias

[Kevin Darcy]

Jim McCullars wrote:

>Hello:
>
>   Hope this is the correct group to ask this question to.  We have a web 
>server whose real name is info.uah.edu, but it has several aliases
>(including www) for various name virtual hosts (science.uah.edu, 
>staffsenate.uah.edu, etc).  Our student newspaper wanted to use this feature,
>so we added this:
>
>exponent        IN      CNAME   info.uah.edu.
>
>but they also want to be able to get mail @exponent.uah.edu, and I want an
>MX to our campus email server, email.uah.edu.  Apparently, when you have a
>CNAME, you cannot have another record type, so I can't just add an MX to
>what I have above.  What would be the recommended way to do what I want?
>Create an A record for exponent, with the IP address of info, and then an
>MX to email?  If I do that, will I break the sendmail (or something else)
>on email or info?  Thanks for any advice...
>
Yes, it is possible that by "unaliasing" "exponent" you may break 
something, depending on how convoluted your mail config/architecture is. 
But your basic choices are to either change "exponent" to be an A record 
or to teach "info" to forward "exponent's" mail to the right place 
(generally speaking I would not create an extraneous mail hop, and 
potential point of failure, without a very good reason). DNS'es "CNAME 
and other data" rule cannot be broken except by old, non-conforming 
software that would cause more problems than it solves.

                                                                         
                                    - Kevin