Drupal multisite

setting up virtual host
cp /etc/apache2/sites-enabled/000-default /etc/apache2/sites-enabled/somethin.com
Eg
<VirtualHost azhikkodu.com>
        ServerAdmin webmaster@localhost

        DocumentRoot /home/space/public_html/drupal

Edit Document root  in the file
cp DRUPAL_DIRECTORY/sites/default DRUPAL_DIRECTORY/sites/somethin.com
Edit $base_url
Edit /etc/host file
as
 ipaddress   somethin.com