On a Cisco router, which interface configuration command correctly enables OSPFv3 (the IPv6 version of OSPF) for a given process and area on that interface?

Introduction / Context:
For IPv6 routing, traditional IPv4 routing protocols such as OSPF have updated versions, like OSPFv3. On Cisco IOS, the configuration model for IPv6 routing protocols is slightly different from IPv4, and many exams test whether you recognize the correct interface level commands for enabling OSPFv3.

Given Data / Assumptions:

• We want to enable OSPFv3, which is the version of OSPF used for IPv6.
• The configuration is being entered under interface configuration mode.
• The process identifier is 10 and the area is the backbone area 0.
• The options include commands that belong to different routing protocols.

Concept / Approach:
In Cisco IOS, OSPFv3 for IPv6 is configured partly in global routing process configuration and partly under interfaces. The interface level command uses the ipv6 ospf process-id area area-id syntax. For example, ipv6 ospf 10 area 0.0.0.0 enables OSPFv3 process 10 for that interface in area 0. The other commands listed belong to IPv6 RIPng, IPv6 EIGRP, or are syntactically invalid for enabling OSPFv3 on an interface.

Step-by-Step Solution:
1. Identify the protocol we are enabling: OSPFv3 for IPv6.2. Recall the correct interface level syntax: ipv6 ospf process-id area area-id.3. Substitute the process-id 10 and backbone area 0, which is often written as 0.0.0.0.4. This yields the command ipv6 ospf 10 area 0.0.0.0 under the interface configuration.5. Compare this to the options and confirm that option A matches exactly.

Verification / Alternative check:
Cisco documentation for OSPFv3 configuration shows that after enabling IPv6 unicast routing and defining the OSPFv3 process, you apply OSPF to interfaces using the ipv6 ospf command. Laboratory practice on a Cisco router or simulation platform confirms that this is the command actually used to bring an interface into an OSPFv3 area.

Why Other Options Are Wrong:
Option B, ipv6 router rip 1, belongs to RIPng configuration and is not the command used under an interface to enable OSPFv3. Option C, ipv6 router eigrp 10, relates to IPv6 EIGRP configuration, again not OSPF. Option D, ospf ipv6 10 area 0, has incorrect syntax and does not match Cisco IOS commands for OSPFv3.

Common Pitfalls:
Students often confuse the placement of routing protocol configuration between global and interface modes or mix command words from IPv4 and IPv6 versions. Another pitfall is forgetting that OSPFv3 associates directly with interfaces rather than relying solely on network statements as in many IPv4 configurations. Remember the ipv6 ospf process-id area area-id pattern when answering similar questions.

Final Answer:
Router1(config-if)# ipv6 ospf 10 area 0.0.0.0