With this update, Azure DNS guarantees that DNS requests will receive a response from at least one name server 100% of the time. If you don’t know, Azure DNS is a hosting service for DNS domains, providing name resolution using Microsoft Azure infrastructure. By hosting your domains in Azure, you can manage your DNS records using the same credentials, APIs, tools, and billing as your other Azure services.
DNS domains in Azure DNS are hosted on Azure’s global network of DNS name servers. This uses Anycast networking so that each DNS query is answered by the closest available DNS server.
Your domains and records can be managed via the Azure portal, Azure PowerShell cmdlets, and the cross-platform Azure CLI. Applications requiring automatic DNS management can integrate with the service via the REST API and SDKs.
If you want to know more, check out this link: https://azure.microsoft.com/es-es/services/dns/