The answer is that the series of asterisks indicates intermediate routers are not responding to ICMP time-exceeded messages. This happens because traceroute works by sending packets with incrementally increasing Time-to-Live (TTL) values; when a router decrements the TTL to zero, it should reply with an ICMP Time-Exceeded message to identify itself. If a router is configured to filter or drop ICMP traffic, it simply forwards the packet without sending that reply, so the traceroute output shows asterisks for that hop. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding that asterisks do not mean the destination is unreachable—the final hop succeeded, so the path is intact. A common trap is assuming asterisks equal a broken route or packet loss, but the real issue is ICMP filtering by intermediate routers. Memory tip: “Asterisks are silent stars—routers that don’t reply, not routers that die.”
N10-009 Network Troubleshooting Practice Question
This N10-009 practice question tests your understanding of network troubleshooting. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network technician runs the command "traceroute 8.8.8.8" from a workstation. The output shows the first hop as the default gateway, the second hop as an internal router, and then a series of asterisks (* * *) before reaching the destination. What does the series of asterisks indicate?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Why wrong: The traceroute eventually reaches the destination (8.8.8.8), so the destination is not unreachable; only responses from intermediate hops are missing.
B
The intermediate routers are not responding to ICMP time-exceeded messages
Asterisks indicate that those routers did not send back the ICMP time-exceeded message, often due to firewall filtering.
C
The TTL expired at the last hop
Why wrong: If TTL expired at the last hop, the final hop would show the destination itself, not asterisks.
D
The connection is encrypted
Why wrong: Encryption does not prevent traceroute from receiving ICMP responses; encryption is irrelevant to the ICMP protocol.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The intermediate routers are not responding to ICMP time-exceeded messages
The series of asterisks indicates that intermediate routers beyond the second hop are not responding with ICMP Time-Exceeded messages when the TTL expires. Traceroute relies on these ICMP responses to identify each hop; if a router is configured to drop ICMP or not send the message, the output shows asterisks for that hop. The destination is still reachable, as the final hop succeeds, so the asterisks do not indicate unreachability.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The destination is unreachable
Why it's wrong here
The traceroute eventually reaches the destination (8.8.8.8), so the destination is not unreachable; only responses from intermediate hops are missing.
✓
The intermediate routers are not responding to ICMP time-exceeded messages
Why this is correct
Asterisks indicate that those routers did not send back the ICMP time-exceeded message, often due to firewall filtering.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The TTL expired at the last hop
Why it's wrong here
If TTL expired at the last hop, the final hop would show the destination itself, not asterisks.
✗
The connection is encrypted
Why it's wrong here
Encryption does not prevent traceroute from receiving ICMP responses; encryption is irrelevant to the ICMP protocol.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that asterisks mean the destination is unreachable, but the key is that traceroute still reaches the final hop, so the asterisks only indicate missing ICMP responses from intermediate routers, not a failure to reach the target.
Trap categories for this question
Command / output trap
If TTL expired at the last hop, the final hop would show the destination itself, not asterisks.
Detailed technical explanation
How to think about this question
Traceroute works by sending UDP or ICMP Echo packets with incrementing TTL values; each router decrements the TTL and, when it reaches zero, sends an ICMP Time-Exceeded (Type 11, Code 0) message back to the source. Asterisks appear when a router is configured to filter or rate-limit ICMP (e.g., via access control lists or firewall rules) or when the router simply does not generate the Time-Exceeded message, which is common in load-balanced paths where packets take different routes. In real-world scenarios, a single asterisk can indicate a transient issue, but a full series often points to a security policy blocking ICMP at a specific network segment.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
Network Troubleshooting — This question tests Network Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The intermediate routers are not responding to ICMP time-exceeded messages — The series of asterisks indicates that intermediate routers beyond the second hop are not responding with ICMP Time-Exceeded messages when the TTL expires. Traceroute relies on these ICMP responses to identify each hop; if a router is configured to drop ICMP or not send the message, the output shows asterisks for that hop. The destination is still reachable, as the final hop succeeds, so the asterisks do not indicate unreachability.
What should I do if I get this N10-009 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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