Question 639 of 2,152

IPv6 First Hop Security →hardMultiple ChoiceObjective-mapped

300-410 IPv6 First Hop Security Practice Question

This 300-410 practice question tests your understanding of ipv6 first hop security. 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 IPv6 ND inspection:

R1# debug ipv6 nd inspection

*Mar  1 00:02:34.567: IPv6-ND-Inspection: R1, Fa0/0, NS from fe80::1 to ff02::1, target 2001:db8::1, options: SLLA 0011.2233.4455
*Mar  1 00:02:34.567: IPv6-ND-Inspection: R1, Fa0/0, NS from fe80::1 to ff02::1, target 2001:db8::1, SLLA 0011.2233.4455 is allowed by policy INSPECT
*Mar  1 00:02:35.890: IPv6-ND-Inspection: R1, Fa0/0, NA from fe80::2 to fe80::1, target 2001:db8::2, options: TLLA 00aa.bbcc.ddee
*Mar  1 00:02:35.890: IPv6-ND-Inspection: R1, Fa0/0, NA from fe80::2 to fe80::1, target 2001:db8::2, TLLA 00aa.bbcc.ddee is blocked by policy INSPECT

What does this output indicate?

Question 1hardmultiple choice

Study the full IPv6 explanation →

A
ND inspection is allowing NS messages but blocking NA messages from fe80::2, likely due to a MAC address mismatch or policy violation.
The NA is blocked, which could be due to the source MAC not matching the TLLA or policy rules.
B
ND inspection is blocking all NS and NA messages, indicating a misconfiguration.
Why wrong: The NS from fe80::1 is allowed, so not all messages are blocked.
C
ND inspection is allowing all messages but logging them for analysis.
Why wrong: The NA is explicitly blocked, so not all are allowed.
D
ND inspection is not configured; the debug output is from default ND behavior.
Why wrong: The debug references policy INSPECT, indicating ND inspection is configured.

Full breakdown with real-world context →

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

✓

ND inspection is allowing NS messages but blocking NA messages from fe80::2, likely due to a MAC address mismatch or policy violation.

The debug shows ND inspection processing NS and NA messages. The NS from fe80::1 is allowed, but the NA from fe80::2 is blocked, indicating a possible spoofing attempt or policy violation.

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.

✓
ND inspection is allowing NS messages but blocking NA messages from fe80::2, likely due to a MAC address mismatch or policy violation.
Why this is correct
The NA is blocked, which could be due to the source MAC not matching the TLLA or policy rules.
Related concept
Read the scenario before looking for a memorised answer.
✗
ND inspection is blocking all NS and NA messages, indicating a misconfiguration.
Why it's wrong here
The NS from fe80::1 is allowed, so not all messages are blocked.
✗
ND inspection is allowing all messages but logging them for analysis.
Why it's wrong here
The NA is explicitly blocked, so not all are allowed.
✗
ND inspection is not configured; the debug output is from default ND behavior.
Why it's wrong here
The debug references policy INSPECT, indicating ND inspection is configured.

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.

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?

IPv6 First Hop Security — This question tests IPv6 First Hop Security — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: ND inspection is allowing NS messages but blocking NA messages from fe80::2, likely due to a MAC address mismatch or policy violation. — The debug shows ND inspection processing NS and NA messages. The NS from fe80::1 is allowed, but the NA from fe80::2 is blocked, indicating a possible spoofing attempt or policy violation.

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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