The correct answer is that the TTL value in the ping packet is too low, as this causes the packet to expire before reaching the destination. When a router receives a packet with a TTL of zero, it discards the packet and sends an ICMP Time Exceeded message, but if the sender never receives a reply, it indicates the packet was dropped mid-path. On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding of how the Time to Live field prevents routing loops and how a low TTL leads to a "ping request timed out" error—a common trap is confusing this with network congestion or firewall blocks. Remember that Linux defaults to a TTL of 64, so if your route requires more than 64 hops, the packet will be silently discarded. A helpful memory tip: "TTL too low, packet won't go—count your hops before you throw."
XK0-005 Troubleshooting Practice Question
This XK0-005 practice question tests your understanding of troubleshooting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Refer to the exhibit.
$ ping -c 2 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=1 Time to live exceeded
From 192.168.1.1 icmp_seq=2 Time to live exceeded
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss
A user runs the ping command and receives the output shown in the exhibit. Which of the following is the MOST likely cause of the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Refer to the exhibit.
$ ping -c 2 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=1 Time to live exceeded
From 192.168.1.1 icmp_seq=2 Time to live exceeded
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss
A
The destination host is down.
Why wrong: A down host would give no response or 'Destination Host Unreachable'.
B
The local system does not have a default gateway configured.
Why wrong: If no default gateway, the system would not send packets at all.
C
There is a routing loop causing packets to be dropped.
Why wrong: A routing loop would show increasing TTL and eventually be dropped, but the message would be different.
D
The TTL value in the ping packet is too low.
TTL exceeded indicates the packet's TTL reached zero before reaching the destination.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The TTL value in the ping packet is too low.
The output shows 'Request timed out' or similar, which can occur when the TTL (Time to Live) value in the ping packet expires before reaching the destination. A TTL that is too low causes routers to decrement the value to zero and drop the packet, sending an ICMP Time Exceeded message back to the sender, but if the sender does not receive a reply, it indicates the packet never reached the destination. This is the most likely cause because the ping command uses a default TTL (e.g., 128 on Windows, 64 on Linux), and if the path requires more hops, the packet is silently discarded.
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 host is down.
Why it's wrong here
A down host would give no response or 'Destination Host Unreachable'.
✗
The local system does not have a default gateway configured.
Why it's wrong here
If no default gateway, the system would not send packets at all.
✗
There is a routing loop causing packets to be dropped.
Why it's wrong here
A routing loop would show increasing TTL and eventually be dropped, but the message would be different.
✓
The TTL value in the ping packet is too low.
Why this is correct
TTL exceeded indicates the packet's TTL reached zero before reaching the destination.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume 'Request timed out' always means the destination is down, but Cisco tests the nuance that a low TTL can cause silent packet drops without any ICMP error reaching the source, especially if the source does not process ICMP Time Exceeded messages or if the router is configured to drop rather than notify.
Trap categories for this question
Command / output trap
A routing loop would show increasing TTL and eventually be dropped, but the message would be different.
Detailed technical explanation
How to think about this question
The TTL field in IPv4 (or Hop Limit in IPv6) is decremented by each router; when it reaches zero, the router drops the packet and sends an ICMP Time Exceeded (Type 11, Code 0) message to the source. In a real-world scenario, a misconfigured application or firewall might set an abnormally low TTL (e.g., 1), causing pings to fail even though the destination is reachable with a higher TTL. Tools like 'tracert' (Windows) or 'traceroute' (Linux) exploit this behavior by sending packets with incrementing TTL values to map the network path.
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 XK0-005 question in full detail.
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The TTL value in the ping packet is too low. — The output shows 'Request timed out' or similar, which can occur when the TTL (Time to Live) value in the ping packet expires before reaching the destination. A TTL that is too low causes routers to decrement the value to zero and drop the packet, sending an ICMP Time Exceeded message back to the sender, but if the sender does not receive a reply, it indicates the packet never reached the destination. This is the most likely cause because the ping command uses a default TTL (e.g., 128 on Windows, 64 on Linux), and if the path requires more hops, the packet is silently discarded.
What should I do if I get this XK0-005 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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