Question 820 of 2,152

IPv6 First Hop Security →hardMultiple SelectObjective-mapped

300-410 IPv6 First Hop Security Practice Question

This 300-410 practice question tests your understanding of ipv6 first hop security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.

Which TWO statements about IPv6 First Hop Security (FHS) RA Guard are true? (Choose TWO.)

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.

A
The default RA Guard policy action is to block Router Advertisements from unauthorized ports.
Correct. The default action for an RA Guard policy is 'block', which drops unauthorized RAs.
B
RA Guard validates the source MAC address of Router Advertisements against the IPv6 source address.
Why wrong: Incorrect. RA Guard does not perform source MAC validation; it checks router preference and hop limit fields.
C
The default RA Guard policy action is to log Router Advertisements from unauthorized ports.
Why wrong: Incorrect. The default action is 'block', not 'log'. Logging can be configured separately.
D
RA Guard can be applied on a per-interface or per-VLAN basis using a policy map.
Correct. RA Guard policies are applied using a policy map that can be attached to an interface or a VLAN.
E
RA Guard is typically enabled on trunk ports to protect against rogue RAs from other VLANs.
Why wrong: Incorrect. RA Guard is usually applied on access ports; trunk ports often need to forward legitimate RAs.

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

✓

The default RA Guard policy action is to block Router Advertisements from unauthorized ports.

Option A is correct because the default action of an IPv6 RA Guard policy is to block Router Advertisements (RAs) received on ports that are not explicitly authorized. This prevents rogue devices from sending malicious RAs that could redirect traffic or launch man-in-the-middle attacks. The RA Guard feature enforces this by dropping unauthorized RAs at the switch level.

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 default RA Guard policy action is to block Router Advertisements from unauthorized ports.
Why this is correct
Correct. The default action for an RA Guard policy is 'block', which drops unauthorized RAs.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
RA Guard validates the source MAC address of Router Advertisements against the IPv6 source address.
Why it's wrong here
Incorrect. RA Guard does not perform source MAC validation; it checks router preference and hop limit fields.
✗
The default RA Guard policy action is to log Router Advertisements from unauthorized ports.
Why it's wrong here
Incorrect. The default action is 'block', not 'log'. Logging can be configured separately.
✓
RA Guard can be applied on a per-interface or per-VLAN basis using a policy map.
Why this is correct
Correct. RA Guard policies are applied using a policy map that can be attached to an interface or a VLAN.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
RA Guard is typically enabled on trunk ports to protect against rogue RAs from other VLANs.
Why it's wrong here
Incorrect. RA Guard is usually applied on access ports; trunk ports often need to forward legitimate RAs.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between the default action (block) and optional actions (log), and the specific validation of source MAC against link-local IPv6 address rather than any IPv6 address, leading candidates to confuse the validation scope.

Detailed technical explanation

How to think about this question

Under the hood, RA Guard uses a policy map that references a class map matching IPv6 Router Advertisements (based on ICMPv6 type 134). The policy can be applied per interface or per VLAN using the 'ipv6 nd raguard' command. In real-world scenarios, RA Guard is critical in enterprise networks to prevent rogue RAs from misconfiguring host routing tables, which could lead to traffic interception or denial of service.

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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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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: The default RA Guard policy action is to block Router Advertisements from unauthorized ports. — Option A is correct because the default action of an IPv6 RA Guard policy is to block Router Advertisements (RAs) received on ports that are not explicitly authorized. This prevents rogue devices from sending malicious RAs that could redirect traffic or launch man-in-the-middle attacks. The RA Guard feature enforces this by dropping unauthorized RAs at the switch level.

What should I do if I get this 300-410 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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