Gateway1 currently provides access to App1 at https://app1.contoso.com. You have deployed a new web app App2 and need Gateway1 to route https://app2.contoso.com to App2 while minimizing administrative effort. What should you add or configure on Gateway1?

To route traffic for a new web app (App2) through an existing Azure Application Gateway (Gateway1) while minimizing administrative effort, you need to configure three components: a listener, a backend pool, and a routing rule. The listener defines the frontend IP address, port, and protocol (HTTPS for app2.contoso.com) that the Application Gateway listens on. The backend pool specifies the destination servers or services where App2 is hosted. Finally, the routing rule connects the listener to the backend pool, defining how incoming requests matching the listener's criteria (e.g., host header for app2.contoso.com) are forwarded to the correct backend pool. Without all three, the Application Gateway cannot properly receive, interpret, and forward the traffic for the new application.