Bind
-----

www.miodominio.com IN CNAME miodominio.com

Nota: non dimenticare i punti!

Apache2
---------

in /etc/apache2/sites-available/miodominio.conf:

DocumentRoot /home/sito/www
ServerName miodominio.com
<Directory "/home/sito/www">
allow from all
Options +Indexes
</Directory>
ServerAlias www.miodominio.com