A multicast network is using bidirectional PIM. Which two actions, when combined, can achieve high availability so that two RPs within the same network can act in a redundant manner? (Choose two.)

MSDP is used with PIM-SM Anycast RP to synchronize active source state between multiple RPs, but bidirectional PIM has no concept of active sources or MSDP, making this approach incompatible with bidir PIM.

A phantom RP is a virtual IP address not assigned to any router interface; all multicast groups are configured to use this address as the RP. Both physical RPs advertise host routes or prefixes covering the phantom address so traffic is routed to one of them, decoupling the RP identity from any single physical device.

Advertising routes to both RPs with the same subnet mask length produces equal-cost paths, which results in unpredictable load sharing rather than the deterministic active/standby selection required for correct bidir PIM RP redundancy.

By advertising the phantom RP address from each physical RP using different subnet mask lengths - a longer prefix from the primary and a shorter prefix from the backup - unicast routing always installs the longer-match route to the primary RP. When the primary fails, the shorter backup prefix becomes the best match, achieving automatic and deterministic failover without any multicast-specific protocol changes.

Administrative distance controls which routing protocol's routes are preferred in the RIB, not which of two same-protocol routes to a single destination is selected, so it cannot provide the per-RP preference needed for bidir PIM redundancy.

Static mroutes influence RPF lookups in the multicast routing table but do not create the phantom RP mechanism needed for bidir PIM RP redundancy and provide no automatic failover when the active RP fails.