You deployed a new Azure App Service web app that must use Azure Active Directory for user authentication and authorization. What is the first configuration step you should take?

To enable Azure Active Directory (AAD) authentication for an Azure App Service, the first step is to configure an identity provider. Azure App Service can integrate directly with AAD as an identity provider, simplifying the authentication process. This involves registering your application within AAD and then configuring the App Service to use that AAD application for authentication. Mapping an existing custom DNS name is for domain access, not authentication. Creating a new app setting might be part of later configuration but isn't the initial step for enabling AAD. Adding a private certificate is typically for custom domains with SSL/TLS or client certificates, not the primary AAD integration. Creating a managed identity is for Azure resource authentication, not user authentication to the web app itself.