Five, Traceroute
Traceroute is an important tool used by routing situation between the detection of the destination host to host, it is the most convenient tool.
Traceroute principle is very, very interesting, it receives the IP destination host, the destination host to send a first TTL = UDP packet 1, and the first router through which the packet has been received, it is automatically TTL is decremented by one, and after the TTL becomes 0, put the router packet abandoned, and at the same time produce a host unreachable ICMP packets to the host. After the host receives the datagram then send a TTL = UDP datagram to the destination host 2, then stimulated router to the second host computer sends ICMP packets. So forth until you reach the destination host. In this way, traceroute got the all routers IP.
