Yes as a way of protection, everyone should redirect traffic from yoursite.com to http://www.yoursite.com.
It’s easy to do. Just use a .htaccess file on your webroot (usually the public_html folder), with the following code:
RewriteEngine On
RewriteCond %{HTTP_HOST} ^yoursite.com$ [NC]
RewriteRule ^(.*)$ http://www.yoursite.com/$1 [R=301,L]