AWS API Gateway won't open up

I created a "hello world" lambda function and then deployed it to an end-point using AWS's API Gateway:

All very much basic settings but I was sure to change the security to "open" and while i was told that it could take up for 15 minutes for the domain to resolve I found that even after 30 I was getting the following response from the "open" end-point:

 {"message":"Missing Authentication Token"}

Am I missing something obvious? Shouldn't this have been available with what I did?