The last couple of months we have been experiencing intermittent issues resolving the A records that are served by the Azure DNS service (currently in preview).
Before that we had similar issues, but at a much higher frequency, related to MX records.
You could then execute dig -t MX ourdomain.com @[azure name server host name] and every other call would not give the desired reply.
Our current issue is not that easy to reproduce. We discovered it in log files for apps that are calling services using the hostname provided by our zones in Azure DNS.
The error message we get in the logs are:
ERROR: getaddrinfo ENOTFOUND
When we had the bug (now fixed, thank you) with the MX records we had similar issues but in bounce reports that said that the name of the mail server could not be resolved, which is ENOTFOUND in other words.
Worth noting is that all host names that we have this issue with represented by a wildcard A record in the DNS zone in Azure DNS. From one second to the other one host name served by the willdcard record can't be resolved, and the next second it works again.
To us it seems we have a similar issue as the previous one with the MX records.