traceroute is a computer network diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol, mechanism of this protocol as following, The end user Sends a packet from the source to destination with TTL value= 1 and the first hop decrease this value to be = 0 plus this interface sent an exceeded TTL message inform the source that this ICMP packet decreased to zero so the source will send packet with the oldest value =1 plus one to be =2 and so on to arrive at the destination address.