Merge pull request #274026 from greg-lindsay/appgw-freshness

replace PR 268890

Author: prmerger-automator[bot]

articles/application-gateway/configuration-infrastructure.md

@@ -5,7 +5,7 @@ services: application-gateway
 author: greg-lindsay
 ms.service: application-gateway
 ms.topic: conceptual
-ms.date: 04/25/2024
+ms.date: 05/01/2024
 ms.author: greglin
 ---
 
@@ -63,6 +63,8 @@ It's possible to change the subnet of an existing Application Gateway instance w
 
 The virtual network resource supports [DNS server](../virtual-network/manage-virtual-network.yml#view-virtual-networks-and-settings-using-the-azure-portal) configuration, which allows you to choose between Azure-provided default or custom DNS servers. The instances of your application gateway also honor this DNS configuration for any name resolution. After you change this setting, you must restart ([Stop](/powershell/module/az.network/Stop-AzApplicationGateway) and [Start](/powershell/module/az.network/start-azapplicationgateway)) your application gateway for these changes to take effect on the instances.
 
+When an instance of your Application Gateway issues a DNS query, it uses the value from the server that responds first.
+
 > [!NOTE]
 > If you use custom DNS servers in the Application Gateway virtual network, the DNS server must be able to resolve public internet names. Application Gateway requires this capability.
 

articles/application-gateway/how-application-gateway-works.md

@@ -5,7 +5,7 @@ services: application-gateway
 author: greg-lindsay
 ms.service: application-gateway
 ms.topic: conceptual
-ms.date: 8/22/2023
+ms.date: 05/01/2024
 ms.author: greglin
 ---
 
@@ -58,8 +58,8 @@ When a backend pool's server is configured with a Fully Qualified Domain Name (F
 The Application Gateway retains this cached information for the period equivalent to that DNS record's TTL (time to live) and performs a fresh DNS lookup once the TTL expires. If a gateway detects a change in IP address for its subsequent DNS query, it will start routing the traffic to this updated destination. In case of problems such as the DNS lookup failing to receive a response or the record no longer exists, the gateway continues to use the last-known-good IP address(es). This ensures minimal impact on the data path.
 
 > [!IMPORTANT]
->  * When using custom DNS servers with Application Gateway's Virtual Network, it is crucial that all servers are identical and respond consistently with the same DNS values.
->  * Users of on-premises custom DNS servers must ensure connectivity to Azure DNS through [Azure DNS Private Resolver](../dns/private-resolver-hybrid-dns.md) (recommended) or DNS forwarder VM when using a Private DNS zone for Private endpoint.
+>  * When using custom DNS servers with Application Gateway's Virtual Network, it is important that all servers respond consistently with the same DNS values. When an instance of your Application Gateway issues a DNS query, it uses the value from the server that responds first.
+>  * Users of on-premises custom DNS servers must ensure connectivity to Azure DNS through [Azure DNS Private Resolver](../dns/private-resolver-hybrid-dns.md) (recommended) or a DNS forwarder VM when using a Private DNS zone for Private endpoint.
 
 ### Modifications to the request