Question 762 of 2,152

Network Logging and Syslog →mediumMultiple ChoiceObjective-mapped

Debug IP Packet Output Interpretation — Identifying Routing Loops

This 300-410 practice question tests your understanding of network logging and syslog. 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.

A network engineer runs the following command to troubleshoot a Network Logging and Syslog issue:

R1# debug ip packet

Output: IP: s=10.1.1.1 (GigabitEthernet0/1), d=10.2.2.2, len 100, rcvd 3 IP: s=10.1.1.1 (GigabitEthernet0/1), d=10.2.2.2, len 100, rcvd 4 IP: s=10.1.1.1 (GigabitEthernet0/1), d=10.2.2.2, len 100, rcvd 5

What does this output indicate?

A
The router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination.
Repeated identical packets suggest a loop; debug ip packet should be used cautiously and stopped with 'undebug all'.
B
The router is functioning normally; these are just normal IP packets being forwarded.
Why wrong: The high count of identical packets is abnormal and indicates a potential issue.
C
The router is receiving multicast traffic and showing each packet individually.
Why wrong: The output shows unicast IP packets, not multicast.
D
The debug command is not working correctly because the output is too repetitive.
Why wrong: The debug is functioning; repetition indicates a network issue.

Full breakdown with real-world context →

Quick Answer

The answer is a routing loop, as the repeated debug ip packet output shows the same packet (source 10.1.1.1, destination 10.2.2.2) being received multiple times on the same interface with incrementing counters (rcvd 3, 4, 5). This pattern indicates the packet is cycling through the router without being forwarded to a new destination, a classic sign of a routing loop where the packet’s TTL is not decrementing properly or the routing table points back to the same router. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your ability to interpret debug output for loop detection, often appearing as a distractor where you must distinguish between normal retransmissions and a true loop. A common trap is assuming high packet counts always mean congestion; instead, focus on the identical source/destination and rising receive counter on the same interface. Memory tip: “Same source, same destination, same interface—think loop, not traffic.”

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination.

The output shows repeated packets from the same source to the same destination, which may indicate a routing loop or excessive traffic. The engineer should use 'undebug all' to stop the debug and then investigate the routing table.

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 router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination.
Why this is correct
Repeated identical packets suggest a loop; debug ip packet should be used cautiously and stopped with 'undebug all'.
Related concept
Read the scenario before looking for a memorised answer.
✗
The router is functioning normally; these are just normal IP packets being forwarded.
Why it's wrong here
The high count of identical packets is abnormal and indicates a potential issue.
✗
The router is receiving multicast traffic and showing each packet individually.
Why it's wrong here
The output shows unicast IP packets, not multicast.
✗
The debug command is not working correctly because the output is too repetitive.
Why it's wrong here
The debug is functioning; repetition indicates a network issue.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.

Trap categories for this question

Command / output trap
The output shows unicast IP packets, not multicast.

Detailed technical explanation

How to think about this question

This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.

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.
Use explanations to understand the rule behind the answer.

TExam Day Tips

Underline the problem statement mentally.
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 practitioner preparing for the 300-410 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

Got this wrong? Here's your next step.

Identify which 300-410 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.

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FAQ

Questions learners often ask

What does this 300-410 question test?

Network Logging and Syslog — This question tests Network Logging and Syslog — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination. — The output shows repeated packets from the same source to the same destination, which may indicate a routing loop or excessive traffic. The engineer should use 'undebug all' to stop the debug and then investigate the routing table.

What should I do if I get this 300-410 question wrong?

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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