OSPFv3 control-plane multicast — selecting the correct groups OSPFv3 uses two well-known IPv6 link-local multicast addresses for hello, database exchange, and LSA flooding. Which pair lists those two addresses?

Introduction / Context:
Every IPv6-capable routing protocol uses specific link-local multicast groups to constrain control-plane chatter to the local segment. OSPFv3 has two groups: one for all OSPF routers and one for designated routers (DR/BDR) on multiaccess networks. Recognizing these targets helps decode control-plane traffic and confirm healthy adjacencies.

Given Data / Assumptions:

• We are selecting from the set {FF02::A, FF02::9, FF02::5, FF02::6}.
• We assume standard OSPFv3 operation on broadcast or NBMA segments.

Concept / Approach:
OSPFv3 uses FF02::5 (AllSPFRouters) for general hello and LSA flooding to all routers participating on the link. It uses FF02::6 (AllDRouters) for messages intended for designated routers and backups to reduce flooding overhead on multiaccess networks. FF02::9 is RIPng and FF02::A is EIGRPv6, so they do not apply to OSPFv3.

Step-by-Step Solution:
Map each option to its protocol: ::5 and ::6 → OSPFv3; ::9 → RIPng; ::A → EIGRPv6.Select the pair that includes ::5 and ::6.

Verification / Alternative check:
Use a packet capture on an OSPFv3-enabled interface; hello packets will target FF02::5, and certain LSAs and acknowledgments use FF02::6 when DR/BDR roles exist.

Why Other Options Are Wrong:

• A/B/C: These omit at least one of the required OSPFv3 multicast addresses.
• E: Includes extra addresses not used by OSPFv3 (RIPng or EIGRPv6 groups).

Common Pitfalls:
Confusing OSPFv3 groups with EIGRPv6 and RIPng or assuming the same multicast addresses as in IPv4, which differ.

Final Answer:
3 and 4