This output indicates the route to reach PC4 from PC1. The packets traverse PC1->PC2->Router1- >PC4.

What will be an ideal response?

No. Time Source Destination Protocol Info
1 0.000000 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33435
2 0.000254 10.0.1.21 10.0.1.11 ICMP Time-to-live exceeded
3 0.001235 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33436
4 0.001424 10.0.1.21 10.0.1.11 ICMP Time-to-live exceeded
5 0.001613 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33437
6 0.001798 10.0.1.21 10.0.1.11 ICMP Time-to-live exceeded
7 0.002043 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33438
8 0.004075 10.0.2.1 10.0.1.11 ICMP Time-to-live exceeded
9 0.004452 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33439
10 0.006447 10.0.2.1 10.0.1.11 ICMP Time-to-live exceeded
11 0.006631 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33440
12 0.008946 10.0.2.1 10.0.1.11 ICMP Time-to-live exceeded
13 0.009175 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33441
14 0.012204 10.0.3.41 10.0.1.11 ICMP Destination unreachable
15 0.012650 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33442
16 0.013575 10.0.3.41 10.0.1.11 ICMP Destination unreachable
17 0.013759 10.0.1.11 10.0.3.41 UDP Source port: 32771 Destination port: 33443
18 0.014700 10.0.3.41 10.0.1.11 ICMP Destination unreachable
19 4.999294 00:04:75:ac:87:22 00:04:75:ad:04:cd ARP Who has 10.0.1.21? Tell 10.0.1.11
20 4.999486 00:04:75:ad:04:cd 00:04:75:ac:87:22 ARP 10.0.1.21 is at 00:04:75:ad:04:cd
From the ethereal output we can see that traceroute program generates one UDP packet to the destination each time. At the first iteration, traceroute sets the TTL field of the UDP packet to be 1. When the packet reach the first router in the route, the TTL field will be reduced by 1 and this gives a 0, since the packet cannot be forwarded, the router replies with an ICMP error message to the sender saying “Time-to-live exceeded”, so the sender now knows who the first router in the route is. The traceroute program then generates another UDP packet with TTL=1, again the ICMP error message will be sent back, traceroute program will then generate a third UDP packet, still with TTL=1, and ICMP error message will again be sent back. In each iteration, traceroute will send 3 UDP packets with the same TTL value and this results in 3 ICMP errors, in this way traceroute measures a router three times in a single iteration. In the second iteration traceroute will set the TTL field of the UDP packets to be 2, now with the same process the second hop in the route will be revealed during this iteration. Traceroute keep increasing the TTL value by 1 for each iteration until the final destination is reached. When the UDP packet generated by traceroute arrives at the final destination, the “Time-to-live exceeded” will not be generated since no more forwarding is needed. Therefore traceroute can no longer use the previous trick on the final destination.But, traceroute manages to force the destination to reply by setting the destination UDP port of the UDP packets to an unused port on the destination host, therefore whenever the UDP packets reach the final destination, the destination is forced to send back an ICMP “Destination unreachable” message. When traceroute receives this message, it knows the final destination has been reached and will not trigger any further iteration, in this way the whole route to a destination is revealed by traceroute.