Update configure-common.md

Added clarification that AlwaysOn needs to receive a 200 OK response to function fully

Author: aevv

articles/app-service/configure-common.md

@@ -440,7 +440,7 @@ Here, you can configure some common settings for the app. Some settings require
     > [!NOTE]
     > Most modern browsers support HTTP/2 protocol over TLS only, while non-encrypted traffic continues to use HTTP/1.1. To ensure that client browsers connect to your app with HTTP/2, secure your custom DNS name. For more information, see [Secure a custom DNS name with a TLS/SSL binding in Azure App Service](configure-ssl-bindings.md).
     - **Web sockets**: For [ASP.NET SignalR] or [socket.io](https://socket.io/), for example.
-    - **Always On**: Keeps the app loaded even when there's no traffic. When **Always On** isn't turned on (default), the app is unloaded after 20 minutes without any incoming requests. The unloaded app can cause high latency for new requests because of its warm-up time. When **Always On** is turned on, the front-end load balancer sends a GET request to the application root every five minutes. The continuous ping prevents the app from being unloaded.
+    - **Always On**: Keeps the app loaded even when there's no traffic. When **Always On** isn't turned on (default), the app is unloaded after 20 minutes without any incoming requests. The unloaded app can cause high latency for new requests because of its warm-up time. When **Always On** is turned on, the front-end load balancer sends a GET request to the application root every five minutes. It's important to ensure this request receives a 200 OK response to ensure any re-imaging operations are performed correctly. The continuous ping prevents the app from being unloaded.
 
         Always On is required for continuous WebJobs or for WebJobs that are triggered using a CRON expression.
     - **ARR affinity**: In a multi-instance deployment, ensure that the client is routed to the same instance for the life of the session. You can set this option to **Off** for stateless applications.