I set up a micro instance (Ubuntu, 32 bit) and assigned an elastic IP (184.108.40.206)
Public DNS: ec2-23-23-245-104.compute-1.amazonaws.com
I successfully ssh'ed to the machine and installed nginx.
Then I edited the server_name attribute in nginx's config file (/etc/nginx/sites-available/default)
Restarted nginx and hit http://ec2-23-23-245-104.compute-1.amazonaws.com but got a "could not connect" error.
What did I forget to do?