Question 623 of 1,819
IP RoutingmediumMultiple SelectObjective-mapped

Quick Answer

The correct answer identifies that OSPFv3 for IPv6 neighbor formation relies on link-local IPv6 addresses (FE80::/10) rather than global unicast addresses, and that the 'show ospfv3 neighbor' command displays the neighbor state, neighbor ID, and interface information. This is because OSPFv3, unlike its IPv4 counterpart, uses link-local addressing as the source for all OSPF packets exchanged between directly connected neighbors, ensuring that adjacency is built without requiring global reachability. On the CCNA 200-301 v2 exam, this topic tests your understanding of how OSPFv3 differs from OSPFv2, particularly the mandatory use of link-local addresses and the explicit interface configuration required under the OSPFv3 process. A common trap is assuming OSPFv3 automatically enables on all IPv6 interfaces or that the neighbor command shows IPv6 addresses—it shows the 32-bit Router ID instead. Memory tip: think "FE80 for neighbors, show ospfv3 neighbor for Router ID and state."

CCNA IP Routing Practice Question

This 200-301 practice question tests your understanding of ip routing. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 correctly describe the configuration and verification of OSPFv3 for IPv6?

Question 1mediummulti select
Review the full OSPF breakdown →

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

OSPFv3 uses link-local IPv6 addresses to form neighbor adjacencies.

OSPFv3 for IPv6 uses link-local IPv6 addresses (FE80::/10) to form neighbor adjacencies, not global unicast addresses (so B is incorrect). OSPFv3 does not automatically enable on all IPv6 interfaces; each interface must be explicitly configured under the OSPFv3 process using the 'ipv6 ospf' command (so C is incorrect). The 'show ospfv3 neighbor' command displays the neighbor's Router ID (a 32-bit value), not the IPv6 address of the neighbor's interface (so E is incorrect). Correct options A and D accurately describe OSPFv3 neighbor formation using link-local addresses and the information shown by the 'show ospfv3 neighbor' command, which includes neighbor state, neighbor ID, and interface.

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.

  • OSPFv3 uses link-local IPv6 addresses to form neighbor adjacencies.

    Why this is correct

    OSPFv3 routers use link-local addresses (FE80::/10) for neighbor discovery and hello packets, ensuring communication remains within the local link.

    Related concept

    Read the scenario before looking for a memorised answer.

  • OSPFv3 uses global unicast IPv6 addresses to form neighbor adjacencies.

    Why it's wrong here

    OSPFv3 uses link-local addresses, not global unicast addresses, for neighbor adjacency. Global addresses are used for routing information but not for neighbor formation.

  • OSPFv3 is automatically enabled on all IPv6-enabled interfaces when the routing process is configured.

    Why it's wrong here

    OSPFv3 must be explicitly enabled on each interface using the 'ipv6 ospf <process-id> area <area-id>' command. It is not automatic.

  • The 'show ospfv3 neighbor' command displays neighbor state, neighbor ID, and interface information.

    Why this is correct

    This command shows neighbor details such as neighbor router ID, state (e.g., FULL/DR), interface, and address, which are critical for verifying OSPFv3 adjacencies.

    Related concept

    Read the scenario before looking for a memorised answer.

  • The 'show ospfv3 neighbor' command displays the IPv6 address of the neighbor's interface as the neighbor ID.

    Why it's wrong here

    The neighbor ID in OSPFv3 is the router ID (typically an IPv4 address or manually configured), not the interface IPv6 address. The command shows the router ID, not the IPv6 address.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

OSPFv3 uses link-local IPv6 addresses to form neighbor adjacencies.Correct answer

Why this is correct

OSPFv3 routers use link-local addresses (FE80::/10) for neighbor discovery and hello packets, ensuring communication remains within the local link.

OSPFv3 uses global unicast IPv6 addresses to form neighbor adjacencies.Wrong answer — click to see why

Why this is wrong here

OSPFv3 uses link-local IPv6 addresses, not global unicast addresses, to form neighbor adjacencies. Global addresses are used for routing information but not for neighbor discovery or hello packets.

Why candidates choose this

Students may confuse OSPFv3 with OSPFv2, which uses IPv4 addresses for neighbor formation, or mistakenly think that global addresses are required for routing protocol communication.

OSPFv3 is automatically enabled on all IPv6-enabled interfaces when the routing process is configured.Wrong answer — click to see why

Why this is wrong here

OSPFv3 must be explicitly enabled on each interface using the 'ipv6 ospf <process-id> area <area-id>' command. It is not automatically enabled on all IPv6-enabled interfaces when the routing process is configured.

Why candidates choose this

Some routing protocols like RIPng are automatically enabled on all interfaces, leading students to incorrectly assume OSPFv3 behaves similarly.

The 'show ospfv3 neighbor' command displays the IPv6 address of the neighbor's interface as the neighbor ID.Wrong answer — click to see why

Why this is wrong here

The neighbor ID in OSPFv3 is the router ID (typically an IPv4 address or manually configured), not the IPv6 address of the neighbor's interface. The 'show ospfv3 neighbor' command displays the router ID, not the interface IPv6 address.

Why candidates choose this

Students may assume that because OSPFv3 is for IPv6, the neighbor ID would be an IPv6 address, but OSPFv3 retains the concept of a 32-bit router ID for identification.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the misconception that OSPFv3 behaves like OSPFv2 by using global unicast addresses for neighbor formation, or that enabling the OSPFv3 process automatically activates it on all interfaces, when in fact each interface must be explicitly enabled under the OSPFv3 process.

Trap categories for this question

  • Command / output trap

    OSPFv3 must be explicitly enabled on each interface using the 'ipv6 ospf <process-id> area <area-id>' command. It is not automatic.

Detailed technical explanation

How to think about this question

OSPFv3, defined in RFC 5340, decouples the protocol from IPv6 addresses by using link-local addresses for all OSPF packets (Hello, DBD, LSR, LSU, LSAck), which reduces reliance on global address configuration. The 'show ospfv3 neighbor' command outputs the neighbor's router ID, state (e.g., FULL/DR), and the interface (e.g., GigabitEthernet0/0), which is critical for troubleshooting adjacency issues in multi-access networks where DR/BDR elections occur. A real-world scenario is when a link-local address changes due to interface renumbering; OSPFv3 automatically adapts without manual reconfiguration of neighbor statements.

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 network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this 200-301 question test?

IP Routing — This question tests IP Routing — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: OSPFv3 uses link-local IPv6 addresses to form neighbor adjacencies. — OSPFv3 for IPv6 uses link-local IPv6 addresses (FE80::/10) to form neighbor adjacencies, not global unicast addresses (so B is incorrect). OSPFv3 does not automatically enable on all IPv6 interfaces; each interface must be explicitly configured under the OSPFv3 process using the 'ipv6 ospf' command (so C is incorrect). The 'show ospfv3 neighbor' command displays the neighbor's Router ID (a 32-bit value), not the IPv6 address of the neighbor's interface (so E is incorrect). Correct options A and D accurately describe OSPFv3 neighbor formation using link-local addresses and the information shown by the 'show ospfv3 neighbor' command, which includes neighbor state, neighbor ID, and interface.

What should I do if I get this 200-301 question wrong?

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

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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