From my understanding - this is not something MS would depend on, it is internal and they have their own separate DNS service - this is from the best of my knowledge, I could be wrong here.
For a comsumer - unless you depend on their DNS service (https://azure.microsoft.com/en-in/services/dns/) it does not matter. The DNS attack would affect the provider it is targeted on. So if you host your DNS on GoDaddy and run a Website in Azure - MS is not responsible for DNS resolution in this scenario.
Hope this answers your query?