Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Why does traceroute reveal each router hop along a path?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Each router appends its hostname to the packet payload
Routers do not normally write hostnames into transit packets.
B
Distractor review
Each router sends an ARP response back to the source
ARP is local-link only and not how traceroute maps routed hops.
C
Best answer
Each router decrements TTL or hop limit, and expired packets trigger ICMP messages
Correct. TTL or hop-limit expiry creates the hop-by-hop responses.
D
Distractor review
Each switch on the path sends a syslog message to the source host
Syslog is not part of normal traceroute operation.
Common exam trap
Common exam trap: answer the scenario, not the keyword
Read the requirement carefully. Cisco often uses subtle wording like 'most efficient' or 'industry standard' to eliminate technically correct but non-optimal answers.
Technical deep dive
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Traceroute uses the TTL or hop limit field in IP packets to discover each router hop along a network path by triggering ICMP Time Exceeded messages.
- Each router decrements the TTL value by one and discards the packet when TTL reaches zero, sending an ICMP message back to the source to indicate the hop.
- Routers do not modify packet payloads to include hostnames, so traceroute relies solely on ICMP messages triggered by TTL expiry to identify hops.
- ARP operates only on the local subnet for MAC address resolution and does not provide information about routed hops in traceroute.
- Switches forward frames based on MAC addresses and do not decrement TTL or generate ICMP Time Exceeded messages, so they do not appear in traceroute results.
- Traceroute packets increment TTL values starting at one, allowing sequential discovery of each router hop until the destination is reached or TTL expires.
- Cisco routers must allow ICMP Time Exceeded messages for traceroute to function properly, as these messages reveal the identity of each hop.
- Misinterpreting traceroute as relying on syslog messages or ARP responses is a common exam mistake that leads to incorrect answer choices.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
Traceroute uses the TTL or hop limit field in IP packets to discover each router hop along a network path by triggering ICMP Time Exceeded messages.
What is the correct answer to this question?
The correct answer is: Each router decrements TTL or hop limit, and expired packets trigger ICMP messages — Traceroute sends packets with increasing TTL or hop-limit values. When the value expires, the router that drops the packet returns an ICMP message, identifying that hop.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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