ICMP applications --ping

The word is derived from sonar ping, and this is also true of the role of the program, which uses ICMP protocol packets to detect whether another host is reachable. Principle is requesting ICMP type code of 0, it is requested by the host with a ICMP echo type code 8. ping program to calculate the time interval, and calculate how many packets are delivered. Users can determine roughly the network. We can see, ping out of time to transfer the data and the TTL. I gave the example is not very good, because the less traveled route, with interest can ping the foreign websites such as sf.net, we can observe some packet loss phenomenon, and running time will be more longer.
ping gave us a chance to see a host route destination host. This is because, ICMP ping requests in each datagram through a router, the router will put their ip into the datagram. The destination host will copy this list to the response ip icmp packet sent back to the host. However, in any case, a list of ip routing head can record is very limited.