Today, my SCOM server noticed me something was wrong with my DNS servers. On both DNS servers I got the following error:
Alert: DNS 2003 Server External Addresses Resolution Alert
Alert description: DNS Server % cannot resolve external address .
Alert view link: %
Since the error began at 01:43 AM, it could not be caused by a manual change on the system. The servers were still running fine, so this probably was a minor issue.
After some regular tests, it appeared to be a DNS caching issue. Clearing the cache on both DNS servers from the DNS console solved everything.
If you have the same issue, clear the cache on the DNS server as shown in the screenshot: