Update ssl-overview.md

Author: jaesoni

articles/application-gateway/ssl-overview.md

@@ -14,6 +14,9 @@ ms.author: mbender
 
 Transport Layer Security (TLS), previously known as Secure Sockets Layer (SSL), is the standard security technology for establishing an encrypted link between a web server and a browser. This link ensures that all data passed between the web server and browsers remain private and encrypted. Application gateway supports both TLS termination at the gateway as well as end to end TLS encryption.
 
+> [!IMPORTANT]
+> Starting **August 31, 2025**, all clients and backend servers interacting with Azure Application Gateway must use Transport Layer Security (TLS) 1.2 or higher, as [support for TLS 1.0 and 1.1 will be discontinued](https://azure.microsoft.com/updates/azure-application-gateway-support-for-tls-10-and-tls-11-will-end-by-31-august-2025).
+
 ## TLS termination
 
 Application Gateway supports TLS termination at the gateway, after which traffic typically flows unencrypted to the backend servers. There are a number of advantages of doing TLS termination at the application gateway: