Debugging DNS with dig and nslookup

DNS failures often appear as application failures:

The fastest way to investigate is to stop treating “DNS” as one component. Record the exact name and record type, identify the resolver being queried, inspect the full response, and compare one layer at a time.

Two command-line tools are widely used for this work:

dig is usually the stronger diagnostic tool. nslookup remains useful when it is the tool available on the affected system.