Every website should have a similar redirect rule in there somewhere (I implement it in PHP). If someone hits yoursite.com, you probably want to redirect them

Every website should have a similar redirect rule in there somewhere (I implement it in PHP). If someone hits yoursite.com, you probably want to redirect them to www.yoursite.com. I whitelist my domains such that if someone goes goes to anything that points to my server and isn't a valid subdomain, they get redirected to www.