For your site type in “www.yoursitename.com”. Look in the address bar where your site name is…is the “www” still there? Now, type in “yoursitename.com” without the “www”. Check again for the “www”.
You want your website to either resolve to “www.yoursitename.com” or “yoursitename.com” – regardless of whether or not “www” is entered. This is called your Preferred domain name. This is important for your search engine results.
You can use a 301 redirect to redirect traffic from your non-preferred domain name. We commonly take care of this in the .htaccess file.