Testing Reachability With Ping

Ping is the most basic connectivity test. It sends a small message to a target host and waits for a reply, answering the question "can I reach this device, and how fast?" If replies come back, the path is working at the network layer. If they time out, something between you and the target is broken. Ping is usually the first tool a technician reaches for.

Ping uses ICMP (Internet Control Message Protocol), sending an Echo Request and expecting an Echo Reply. ICMP is a helper protocol for diagnostics and error messages, not for carrying user data. Because ping operates at the network layer, a successful ping confirms IP connectivity even when higher-layer services like web or email are failing.