Depending on the link type, OSPF sends link-state update packets to which two addresses?

OSPF relies on two IANA-reserved multicast addresses to distribute its control-plane traffic across broadcast and NBMA network types, and Link State Update (LSU) packets, which carry the actual LSAs being flooded, are addressed to one or the other depending on the role of the sending router. The address 224.0.0.5, designated AllSPFRouters, is used when any OSPF router — including a router that is itself the Designated Router or Backup Designated Router — needs to flood an LSU to every OSPF-speaking router on the segment; this is the address used for Hello packets universally and for LSU flooding directed at the entire segment. The address 224.0.0.6, designated AllDRouters, is used specifically by non-DR, non-BDR routers (DROthers) when they need to send an LSU or other update destined for the DR and BDR only, since only the DR and BDR actually listen on this address; the DR then takes responsibility for reflooding that information to the rest of the segment using 224.0.0.5. This two-address design is central to how OSPF achieves flooding efficiency on multi-access networks by funneling updates through the DR rather than requiring full-mesh flooding among every router pair. The addresses 224.0.0.8 and 224.0.0.9 are not used by OSPF at all; 224.0.0.9 is in fact reserved for RIPv2 multicast updates, making it a plausible-looking but incorrect distractor. Reference topics: Junos Enterprise Routing – OSPF, Multicast Addressing for Hello and Link State Update Packets.