A request for the URI is sent to the Application Load Balancer, which normally would route it to one of your targets, but, when you configuring your routing rules to deliver a fixed-response, the load balancer generates the response and sends it directly to the client Your backends do not receive the requests, letting you focus on delivering your application. You can customize the fixed-response page easily through the AWS Web Console.
200 OK Response 404 Not Found Response 599 Customized Error Response