Redirect non-www Traffic to www Using mod_rewrite
This is an example using the modrewrite Apache module to force all traffic to your site to www.yourdomain.com. This can be useful in an SSL context, as well as for SEO purposes. Create a .htaccess file in your webroot (publichtml for cPanel servers) and add the following lines:
RewriteEngine On RewriteCond %{HTTP_HOST} ^your-domain.com RewriteRule (.*) http://www.your-domain.com/$1 [R=301,L]