Which ICMP message is used by the traceroute utility during the process of finding the path between two end hosts?
- time exceeded
- destination unreachable
Explanation: Traceroute progressively increments the TTL (IPv4) or hop limit (IPv6) field (1, 2, 3, 4…) for sending sequence of ping commands. When a router senses that the TTL or hop limit is 0, it will discard the packet and send a time exceeded message to the source of the traceroute. The returned message contains the IP address of the router that discarded the packet. Hence the traceroute utility learns the address of the router. This process continues and provides the trace with the address of each hop (router) as the packets continue traveling through routers to reach the destination.
More Questions: CCNA 1 Module 13 Quiz – ICMP Answers