Applications use the PingCompleted event to get information about the completion status and data collected by a call to one of the SendAsync methods. The PingCompletedEventHandler delegate provides the call back method invoked when SendAsync raises this event.
Ping pingSender = new Ping ();
// When the PingCompleted event is raised, // the PingCompletedCallback method is called.
pingSender.PingCompleted += new PingCompletedEventHandler (PingCompletedCallback);