DNS and connectivity.

DNS resolves domain names into records used to locate services. Connectivity troubleshooting should distinguish name resolution from reachability and application behavior.

Put it into practice.

If a service works by its IP address but fails by hostname, investigate DNS configuration and cached records. If neither works, examine connectivity before assuming DNS is the only cause.

A common mistake

A failed ping does not prove that a web service is down: some systems block ICMP while still accepting the application’s protocol.

Original independent study explanation. Revised October 2026. Practice assumptions are illustrative.