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This option proposes: Inspect PIM-DM neighbor state, source-specific multicast entries, prune interfaces and receiver interest across the branches. It addresses the different topic PIM dense mode flooding and prune mechanisms, not the directly tested IGMP querier membership reports and group timeout failure in the stated incident (A new streaming client joins a group, yet an upstream router lists no downstream IGMP membership because the access VLAN blocks its reports.). The better discriminating check for this case is: Review VLAN IGMP query source, version, group reports, membership timers and the downstream interface in multicast routing state.

This option proposes: Trace IS-IS link-state synchronization through LSP sequence numbers and summary or acknowledgment PDUs when databases differ. It addresses the different topic IS-IS LSP synchronization using CSNP and PSNP, not the directly tested IGMP querier membership reports and group timeout failure in the stated incident (A new streaming client joins a group, yet an upstream router lists no downstream IGMP membership because the access VLAN blocks its reports.).

This option proposes: Check IS-IS level-1-to-level-2 route leaking and the overload bit before selecting a device as a transit path. It addresses the different topic IS-IS routing leakage and overload bit, not the directly tested IGMP querier membership reports and group timeout failure in the stated incident (A new streaming client joins a group, yet an upstream router lists no downstream IGMP membership because the access VLAN blocks its reports.).

This option proposes: Trace PIM-SM receiver joins toward an RP and subsequent shortest-path behavior when investigating delayed or suboptimal multicast. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Check IGMP membership and querier operation on the receiver LAN before changing PIM routing configuration upstream. It addresses the different topic IGMP querier membership reports and group timeout, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Trace an enterprise wireless AP's registration to its access controller and the separation of management from user traffic in supported forwarding modes. It addresses the different topic Large campus WLAN AC AP and CAPWAP architecture, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: PIM-DM generally follows a flood-and-prune model, building source-based multicast distribution where an interface without interested downstream receivers can be pruned to reduce unnecessary traffic. It addresses the different topic PIM dense mode flooding and prune mechanisms, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: IS-IS uses CLNS-based network entities and level-specific hellos; level-1 neighbors normally require compatible area membership, while level-2 adjacencies have different area constraints and still need link and authentication compatibility. It addresses the different topic IS-IS area addresses and adjacency prerequisites, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: IP multicast forwarding commonly uses an RPF check toward the source or rendezvous point to prevent loops, so an otherwise reachable multicast group may fail when packets arrive on an unexpected upstream interface. It addresses the different topic Multicast reverse path forwarding checks, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Compare RP reachability, (*,G) and (S,G) state, PIM join or register messages and RPF interfaces before changing the multicast design. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Inspect PIM-DM neighbor state, source-specific multicast entries, prune interfaces and receiver interest across the branches. It addresses the different topic PIM dense mode flooding and prune mechanisms, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Compare received iBGP routes to the same prefix, LOCAL_PREF values, policy application points and next-hop reachability across edge routers. It addresses the different topic BGP LOCAL_PREF within one autonomous system, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.). The better discriminating check for this case is: Inspect receiver reports containing include/exclude sources, the configured SSM group range and (S,G) state on multicast routers. The targeted correction is: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

That option concerns PIM sparse mode RP shared tree and shortest path transition. That follows from the targeted action: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

That option concerns PIM dense mode flooding and prune mechanisms. That follows from the targeted action: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

That option concerns Network forwarding planes RIB versus FIB. That follows from the targeted action: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

This option proposes: Troubleshoot an IPv6-only gateway resolution fault by searching exclusively for ARP broadcasts and disabling ICMPv6 neighbor solicitation traffic. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Assume that configuring a multicast source anywhere in the network automatically populates IGMP membership on a VLAN where no receiver has joined. It addresses the different topic IGMP querier membership reports and group timeout, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Remove all rendezvous-point configuration from an ASM sparse-mode deployment and assume that every receiver automatically knows each source location. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A campus IPTV application shares one group address among test senders but needs each receiver to subscribe only to the authorized production source.).

This option proposes: Trace PIM-SM receiver joins toward an RP and subsequent shortest-path behavior when investigating delayed or suboptimal multicast. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Distinguish level-1 area routing from level-2 backbone-style interarea routing when troubleshooting a missing destination. It addresses the different topic IS-IS level one versus level two reachability, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Explain how PIM dense mode initially distributes traffic and then prunes interfaces lacking downstream receivers. It addresses the different topic PIM dense mode flooding and prune mechanisms, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: In any-source PIM-SM an RP supports initial shared-tree joining and source registration, while routers may switch to source-rooted shortest-path trees according to configured behavior and traffic. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: IP multicast forwarding commonly uses an RPF check toward the source or rendezvous point to prevent loops, so an otherwise reachable multicast group may fail when packets arrive on an unexpected upstream interface. It addresses the different topic Multicast reverse path forwarding checks, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Huawei route-policy processing applies matching conditions and actions in sequence, and unmatched or explicitly denied routes can be rejected depending on the policy context; inbound and outbound application points are not interchangeable. It addresses the different topic Route-policy node and filtering direction, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Inspect multicast routing entries, incoming interface, unicast RPF route for the source or RP and packet counters on the observed ingress. It addresses the different topic Multicast reverse path forwarding checks, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Compare RP reachability, (*,G) and (S,G) state, PIM join or register messages and RPF interfaces before changing the multicast design. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Inspect the originating ASBR, type 5 LSA, external metric type and metric, cost toward the ASBR and actual selected external next hop. It addresses the different topic OSPF external LSAs and E1 versus E2 cost, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

That option concerns VRRP virtual MAC and endpoint ARP continuity. That follows from the targeted Recommended action: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

That option concerns Multicast reverse path forwarding checks. That follows from the targeted Recommended action: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

That option concerns PIM sparse mode RP shared tree and shortest path transition. That follows from the targeted Recommended action: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service.

This option proposes: Remove all rendezvous-point configuration from an ASM sparse-mode deployment and assume that every receiver automatically knows each source location. It addresses the different topic PIM sparse mode RP shared tree and shortest path transition, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Disable spanning tree on every redundant uplink after seeing an alternate port discard frames, treating the loop-prevention state as a fault. It addresses the different topic RSTP port roles and rapid convergence, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).

This option proposes: Assume PIM-DM always requires a rendezvous point and never initially floods multicast packets to uninterested downstream segments. It addresses the different topic PIM dense mode flooding and prune mechanisms, not the directly tested IGMPv3 source-specific selection and SSM failure in the stated incident (A deployment enables SSM in the routed network while legacy IGMPv2 receiver reports cannot express the requested source filter, so source-specific joining fails.).