Hello Kanu
If I understand correctly, you want to find out how traceroute behaves if you traceroute a wrong nonexistent destination, correct?
So if you have something like this, how is the TTL handled?
C:\> tracert 192.0.2.1
Tracing route to 192.0.2.1 over a maximum of 30 hops
1 2 ms 1 ms 1 ms 192.168.1.1
2 10 ms 9 ms 8 ms 203.0.113.1
3 15 ms 14 ms 13 ms 203.0.113.5
4 22 ms 21 ms 20 ms 198.51.100.9
5 35 ms 34 ms 33 ms 198.51.100.13
6 * * * Request timed out.
7 * * * Request timed out.
8 * * * Request timed out.
9 * * * Request timed out.
10 * * * Request timed out.
11 * * * Request timed out.
12 * * * Request timed out.
13 * * * Request timed out.
14 * * * Request timed out.
15 * * * Request timed out.
16 * * * Request timed out.
17 * * * Request timed out.
18 * * * Request timed out.
19 * * * Request timed out.
20 * * * Request timed out.
21 * * * Request timed out.
22 * * * Request timed out.
23 * * * Request timed out.
24 * * * Request timed out.
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.
So for each additional failed probe, is the TTL increased? Yes it is. This is because you may have routers along the path that are configured to relay traceroute probes, but not to respond to them. So if you have this topology:
…and R2 is configured not to respond to traceroute probes, but it will forward them to the next hop, you could have this:
C:\Users\vmware>tracert 192.168.3.1
Tracing route to 192.168.3.1 over a maximum of 30 hops
1 1 ms 1 ms <1 ms 192.168.1.254
2 * * * Request timed out.
3 1 ms 1 ms 1 ms 192.168.23.3
4 1 ms <1 ms <1 ms 192.168.3.1
Trace complete.
So even though probe 2 failed, you would want probe 3 to increase the TTL so the probe can be relayed to R3. Otherwise, if it does not, it will continue to fail.
Is it possible some other routers in the path or the destination router itself will do something to try to correct such behavior? Well, no, the routers in the path that respond correctly won’t affect how the wrong traceroute behaves. The routing process is independent of how traceroute works, and this is a good thing, because traceroute is used to detect possible failures. If traceroute corrects for those routing failures, then you don’t have a proper diagnostic of the situation of the network… Does that make sense?
I hope this has been helpful!
Laz