5.5 Given a scenario, use the appropriate tool or protocol to solve networking issues.
Objective 5.5 sits in Network Troubleshooting, which carries 24% of the Network+ exam. The questions below are original, written from the official objective title above, and each explanation cites the CompTIA page it rests on.
Objective title verbatim from the official objectives. CompTIA exam page ↗
A worked example
Shown solved, with the whole explanation open: this is what every question here carries.
A technician probes a closed UDP port on a server that responds to ping, and an unreachable message comes back at once. Which device generated it?
The concept
Only the device that owns an address can know which of its own services are listening. A forwarding device can report that it failed to deliver, but it cannot speak to whether a process on another machine is running.
Why this answer
When the IP module on the destination cannot hand a datagram to the named protocol or port because nothing is active there, that host is the device that returns the unreachable message.
- Correct. The destination's own IP module reports the inactive port.
- BThe first router would answer only if the destination network were unroutable from there, which a working ping rules out.
- CThe last router can report an unreachable host, a delivery failure on the final link rather than a closed service.
- DA local stack surfaces errors for its own send failures and cannot know a remote port is closed until something tells it.
Now you: objective 5.5 questions
No account needed. The explanation opens when you answer.
Sample question 1 of 2
A capture holds destination unreachable messages carrying codes 2 and 3. Which device must have produced them?
Sample question 2 of 2
A host receives part of a fragmented datagram, waits past its limit for the rest, and discards what it holds. Which message may it send?
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Read the sources
These are the official pages the questions above cite. Reading them is studying the objective from the primary source, which is what the explanations point you toward anyway.