There is one external domain that used to work, but recently is no longer resolving from our internal network. We use the built-in DNS service from Microsoft Server. Changing the DNS setting on internal systems to an open DNS, such as 220.127.116.11 solves the issue, but this is not ideal as a resolution for our internal systems.
Any ideas what can be checked, why this could be impacting just the Microsoft DNS services? There are no other external domains that seem to be having the issue. Doing packet tracing, they always stop after getting to the internal DNS.