surf mydomain.com vs www.mydomain.com

[Hal Snyder]

Simon Waters wrote:

>A quick peak will show you how....
>
>18:32:26 srw srw $ dig +short mydomain.com
>64.75.34.137
>18:32:31 srw srw $ dig +short www.mydomain.com
>64.75.34.137      
>
>So they create an A record for the domain pointing to the same
>IP address as the www record - bet that one isn't in the archive
>of this list *;-)
>
>Of course the http server will need to know what to do with the
>requests, otherwise you might end up with a site like;
>
>http://kernels.org/
>http://www.kernels.org/
...

On a related note, Cricket Liu's book, 1st ed., p. 100 suggested
creating an A record for the domain pointing to the primary mail
gateway, for broken mail servers that don't grok MX.

Is that point of only historical interest now? Do any known MTAs
today fail to use MX?