PING Sensor

Sending a PING to a server is the most basic and oldest network diagnostic tool. The name comes from the sound that an underwater sonar makes.

To test the availability of a PING sensor bello network monitoring sends an ICMP packet to the ECHO REPLY port of a server and waits for a result. Only if the returned packet still has the same data content the sensor's result is ok.

More:

What it means when the PING sensor is up

What it means when the PING sensor is down