This one is really weird. I've got an Apache web server running on Ubuntu 14.04 with DNS provided by AWS's Route53. When I point a browser (or CURL in a console) to example.com with the http://www in front, the request fails. CURL returns
curl: (6) Could not resolve host: www.example.com
But when I point the same browsers/consoles to example.com, everything works perfectly. /var/log/apache2/error.log reports nothing. Restarting Apache didn't help. As far as I can see, my DNS record set is fine. Any ideas?