Which statement correctly describes tracepath as compared with traditional traceroute?
LPIC-1 Exam 102-500, objective 109. Networking fundamentals medium
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The options
Correct tracepath needs no special privileges and additionally reports the path MTU it discovers
Correct. tracepath, from the iputils package, is designed to run as an ordinary user and prints the path MTU alongside the hops.
Not correct tracepath tests the path with ICMP echo only, while traceroute can never use ICMP
Wrong on both halves. traceroute can be told to use ICMP echo probes with -I, and its default on Linux is UDP probes to high ports.
Not correct tracepath shows only the final destination, not the intermediate routers
Wrong. tracepath lists each hop with its round-trip time, just as traceroute does; that is the entire point of the tool.
Not correct tracepath queries the routing table locally instead of sending packets onto the network
Wrong. Reading the local routing table is what `ip route get DESTINATION` does. tracepath actively probes the path with packets of increasing TTL.
Why
Both tools raise the TTL (IPv6: hop limit) one step at a time and identify each router from the returned ICMP time-exceeded messages. traceroute historically needed root for raw sockets and its non-default probe modes still do; tracepath is unprivileged and adds path-MTU discovery. The IPv6 forms are traceroute6 and tracepath6. Hops shown as `* * *` mean a router did not answer the probes, which is very often deliberate filtering rather than a fault.
Where this comes from
- Cited
- manual page tracepath(8)
Practise this
Reading one question is not practice. The trainer will draw a set from objective 109 and space the ones you get wrong.