CCNP Practice Question: Examine this configuration: interface…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  It enables OSPFv3 process 1 on this interface and assigns it to area 0.

  Why this is correct

  The command 'ipv6 ospf 1 area 0' is the correct IOS interface subcommand to enable OSPFv3, the IPv6-capable version of OSPF, on that link. It starts OSPFv3 process 1 for that interface and places the interface in backbone area 0, which is the mandatory area that interconnects all other areas. The process ID is locally significant, and the area ID is a 32-bit value, with '0' being shorthand for 0.0.0.0.

• ✗

  It enables OSPFv2 process 1 on this interface and assigns it to area 0.

  Why it's wrong here

  This command cannot be enabling OSPFv2 because OSPFv2 is initiated on an interface with 'ip ospf' (or 'ip ospf process-id area area-id'), not 'ipv6 ospf'. The 'ipv6' keyword explicitly invokes OSPFv3, which uses IPv6 link-local addresses and carries IPv6 prefixes. OSPFv2 is for IPv4 and would never use the ipv6 ospf syntax.

• ✗

  It enables OSPFv3 on this interface but the process ID must match the router ospf process ID; if not, it will be ignored.

  Why it's wrong here

  The claim that the interface process ID must match a router OSPF process or be ignored is incorrect. In IOS, the interface command 'ipv6 ospf 1 area 0' is accepted even if 'ipv6 router ospf 1' (or the OSPFv3 router process) is not yet configured; the router simply does not run OSPFv3 on that interface until the process exists. When a matching router process is later created, the interface is automatically associated, and if the process ID never matches, the interface command remains dormant, not 'ignored'. Multiple OSPFv3 processes can coexist, so the interface must select one by process ID, but the command is never deleted or ignored.

• ✗

  It enables OSPFv3 on this interface but area 0 is invalid for IPv6; OSPFv3 uses area 0.0.0.0.

  Why it's wrong here

  This statement confuses OSPFv3 with OSPFv2 addressing rules. Area 0 is entirely valid for OSPFv3; it is the backbone area and is required for multi-area designs. The area identifier is a 32-bit number, and 'area 0' is the decimal equivalent of 0.0.0.0, so the command is legal. OSPFv3 does not change area semantics, it only changes the network-layer protocol and LSA handling.