Azure DNS SLA: Updated to 100%

Azure DNS is now being offered at a 100% availability SLA that's backed by our diverse, geo-redundant DNS infrastructure. With this update, Azure DNS guarantees that valid DNS requests will receive a response from at least one name server 100% of the time. For details, see the [SLA definition](https://aka.ms/azurednssla). * Azure DNS * Services * [ Azure DNS](https://azure.microsoft.com/en-gb/products/dns/)