You have an Application Gateway named AppGW1 that forwards requests to a backend web app App1. You need to change or add server variables in the HTTP response headers returned by App1. Which Application Gateway configuration item should you modify?

The correct answer is rewrites. Azure Application Gateway's Rewrite HTTP headers and URL feature allows you to modify HTTP request and response headers, as well as URL paths, before the requests are sent to the backend or before the responses are sent back to the client. This is the specific feature designed for changing or adding server variables in HTTP response headers. HTTP settings define properties like port, protocol, and cookie-based affinity for backend pools, but they don't directly modify response headers. Rules define how requests are routed from listeners to backend pools, but they don't inherently modify header content. Listeners are responsible for checking for incoming requests on a specific port and protocol, but they don't perform header manipulation.