CCNA IP Routing Practice Question

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

  When an OSPFv3 router sends Hello packets, it uses the IPv6 link-local address assigned to the outgoing interface as the source, and similarly for Database Description and other OSPFv3 packets. Because link-local addresses (FE80::/10) are valid only on the local segment and cannot be routed, they guarantee that OSPFv3 control traffic stays on that link. This design allows an adjacency to form even if the interface has no global IPv6 address configured.

• ✗

  OSPFv3 uses global unicast IPv6 addresses to form neighbor adjacencies.

  Why it's wrong here

  OSPFv3's Hello and Database Description packets are sourced from the interface's link-local IPv6 address (FE80::/10), not from a global unicast address. Global unicast addresses are used only to advertise reachable prefixes within LSAs, never as the source for neighbor discovery or adjacency establishment. Since link-local addresses are not routable, OSPFv3 confines all protocol traffic to the connected link, so this statement is incorrect.

• ✗

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

  Why it's wrong here

  Configuring the OSPFv3 routing process with 'ipv6 router ospf <process-id>' does not automatically activate OSPFv3 on any interface. Instead, an administrator must explicitly enable OSPFv3 on each interface using the command 'ipv6 ospf <process-id> area <area-id>'. Unlike OSPFv2, there is no 'network' statement to match interfaces, so an IPv6-enabled interface with global addresses remains unregistered with OSPFv3 unless it is explicitly added.

• ✓

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

  Why this is correct

  The 'show ospfv3 neighbor' command presents a detailed table that includes each neighbor's router ID, the adjacency state (e.g., FULL, 2WAY, or EXSTART), the local interface where the adjacency formed, and the neighbor's link-local address. This command is the primary tool for verifying that OSPFv3 routers have completed their exchange process and achieved FULL state. It also reveals problems like mismatched areas or MTU issues when neighbors remain stuck in a non-FULL state.

• ✗

  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 field displayed by 'show ospfv3 neighbor' is the 32-bit router ID (RID), which is typically the highest IPv4 address on a loopback or an interface, or the value set with the 'router-id' command. It is never derived from an IPv6 address, even if the router has only IPv6 addresses configured. If an IPv6 address is shown in the output, it appears in a separate 'address' column, while the neighbor ID remains the RID.

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.

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?”