Check for large numbers of hops. In general, barring a network routing issue, a path between a client and an end server should not exceed 20 or 25 hops. If you see traceroute output greater than 20 or 25 hops, please re-run the test to confirm the behavior. Then check your local network environment for any issues that may cause excessive hops. Proceed to the DNS ping test.
Run a ping test to your internal DNS server