update

Author: KumudD

articles/virtual-network/ipv6-add-to-existing-vnet-cli.md

@@ -11,21 +11,46 @@ ms.devlang: na
 ms.topic: article
 ms.tgt_pltfrm: na
 ms.workload: infrastructure-services
-ms.date: 04/01/2020
+ms.date: 10/23/2019
 ms.author: kumud
 ---
 
-# Add IPv6 to an IPv4 application in Azure virtual network - Azure CLI
+# Add IPv6 to an IPv4 application in Azure virtual network - Azure CLI (Preview)
 
 This article shows you how to add IPv6 addresses to an application that is using IPv4 public IP address in an Azure virtual network for a Standard Load Balancer using Azure CLI. The in-place upgrade includes a virtual network and subnet, a Standard Load Balancer with IPv4 + IPV6 frontend configurations, VMs with NICs that have a IPv4 + IPv6 configurations, network security group, and public IPs.
 
+> [!Important]
+> IPv6 support for Azure Virtual Network is currently in public preview. This preview is provided without a service level agreement and is not recommended for production workloads. Certain features may not be supported or may have constrained capabilities. See the [Supplemental Terms of Use for Microsoft Azure Previews](https://azure.microsoft.com/support/legal/preview-supplemental-terms/) for details.
 
 [!INCLUDE [cloud-shell-try-it.md](../../includes/cloud-shell-try-it.md)]
 
 If you decide to install and use Azure CLI locally instead, this quickstart requires you to use Azure CLI version 2.0.28 or later. To find your installed version, run `az --version`. See [Install Azure CLI](/cli/azure/install-azure-cli) for install or upgrade info.
 
 ## Prerequisites
 
+### Register the service
+
+Before you deploy a dual stack application in Azure, you must configure your subscription for this preview feature using the following Azure CLI:
+
+```azurecli
+az feature register --name AllowIPv6VirtualNetwork --namespace Microsoft.Network
+az feature register --name AllowIPv6CAOnStandardLB --namespace Microsoft.Network
+```
+
+It takes up to 30 minutes for feature registration to complete. You can check your registration status by running the following Azure CLI command:
+
+```azurecli
+az feature show --name AllowIPv6VirtualNetwork --namespace Microsoft.Network
+az feature show --name AllowIPv6CAOnStandardLB --namespace Microsoft.Network
+```
+
+After the registration is complete, run the following command:
+
+```azurecli
+az provider register --namespace Microsoft.Network
+```
+
+### Create a Standard Load Balancer
 This article assumes that you deployed a Standard Load Balancer as described in [Quickstart: Create a Standard Load Balancer - Azure CLI](../load-balancer/quickstart-load-balancer-standard-public-cli.md).
 
 ## Create IPv6 addresses
@@ -143,7 +168,8 @@ You can view the IPv6 dual stack virtual network in Azure portal as follows:
 
   ![IPv6 dual stack virtual network in Azure](./media/ipv6-add-to-existing-vnet-powershell/ipv6-dual-stack-vnet.png)
 
-
+> [!NOTE]
+> The IPv6 for Azure virtual network is available in the Azure portal in read-only for this preview release.
 
 ## Clean up resources