Update login-using-aad.md

Author: SanDeo-MSFT

articles/virtual-machines/linux/login-using-aad.md

@@ -65,6 +65,18 @@ The following Azure regions are currently supported during the preview of this f
 
 If you choose to install and use the CLI locally, this tutorial requires that you are running the Azure CLI version 2.0.31 or later. Run `az --version` to find the version. If you need to install or upgrade, see [Install Azure CLI]( /cli/azure/install-azure-cli).
 
+## Network requirements
+
+To enable Azure AD authentication for your Linux VMs in Azure, you need to ensure your VMs network configuration permits outbound access to the following endpoints over TCP port 443:
+https://login.microsoftonline.com
+https://device.login.microsoftonline.com
+https://pas.windows.net
+https://management.azure.com
+https://packages.microsoft.com
+
+> [!NOTE]
+> Currently, Azure Network Security Group (NSG) cannot be configured for VMs enables with Azure AD authentication.
+
 ## Create a Linux virtual machine
 
 Create a resource group with [az group create](/cli/azure/group#az-group-create), then create a VM with [az vm create](/cli/azure/vm#az-vm-create) using a supported distro and in a supported region. The following example deploys a VM named *myVM* that uses *Ubuntu 16.04 LTS* into a resource group named *myResourceGroup* in the *southcentralus* region. In the following examples, you can provide your own resource group and VM names as needed.