Pass Huawei H12-821 Exam in First Attempt Guaranteed!

That option concerns IGMP querier membership reports and group timeout. That follows from the targeted action: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group.

That option concerns IP prefix filtering and exact route-match conditions. That follows from the targeted action: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group.

That option concerns IGMPv3 source-specific selection and SSM. That follows from the targeted action: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group.

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 Multicast reverse path forwarding checks failure in the stated incident (A live classroom video flow reaches a distribution router on a secondary link, but the RPF route points at a different primary uplink and the stream is dropped.).

This option proposes: Change an MST instance's VLAN mapping on one switch only and assume adjacent switches will continue to recognize exactly the same MST region. It addresses the different topic MSTP region and VLAN-to-instance mappings, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A live classroom video flow reaches a distribution router on a secondary link, but the RPF route points at a different primary uplink and the stream is dropped.).

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 Multicast reverse path forwarding checks failure in the stated incident (A live classroom video flow reaches a distribution router on a secondary link, but the RPF route points at a different primary uplink and the stream is dropped.).

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 Multicast reverse path forwarding checks failure in the stated incident (A live classroom video flow reaches a distribution router on a secondary link, but the RPF route points at a different primary uplink and the stream is dropped.).

This option proposes: Use a carefully scoped Huawei IP prefix list to match the intended route ranges and prefix lengths before applying an import or export policy. It addresses the different topic IP prefix filtering and exact route-match conditions, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A live classroom video flow reaches a distribution router on a secondary link, but the RPF route points at a different primary uplink and the stream is dropped.).

This option proposes: Validate physical stack links, member roles and split-brain safeguards before considering a multi-switch logical chassis redundant. It addresses the different topic Switch stacking clustering and split-brain risk, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A live classroom video flow reaches a distribution router on a secondary link, but the RPF route points at a different primary uplink and the stream is dropped.).

This option proposes: Trace source or destination address translation separately from security policy when applications fail across a routed perimeter. It addresses the different topic Huawei firewall NAT and address translation context, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: IGMPv3 can convey source-filter information, enabling Source-Specific Multicast subscriptions for a specified source and group; an SSM design avoids relying on an ASM rendezvous point for that source tree. It addresses the different topic IGMPv3 source-specific selection and SSM, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: DHCP clients initially discover servers using local broadcasts, which are not ordinarily routed; a DHCP relay supplies an appropriate relay address and forwards requests so the server can select the correct address pool. It addresses the different topic DHCP relay across a routed user VLAN, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: Compare matched source/destination NAT rule, translated session tuple, security-zone permission and upstream route to the translated address. It addresses the different topic Huawei firewall NAT and address translation context, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: Review VLAN IGMP query source, version, group reports, membership timers and the downstream interface in multicast routing state. It addresses the different topic IGMP querier membership reports and group timeout, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

That option concerns PIM dense mode flooding and prune mechanisms. That follows from the targeted Recommended action: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group.

That option concerns Huawei firewall NAT and address translation context. That follows from the targeted Recommended action: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group.

That option concerns IGMPv3 source-specific selection and SSM. That follows from the targeted Recommended action: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group.

This option proposes: Configure a Source-Specific Multicast receiver with only an unspecified group and assume no source identity information is ever required. It addresses the different topic IGMPv3 source-specific selection and SSM, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: Assume a configured BFD transmit interval alone exactly equals the detection timeout regardless of the peer's receive requirement or detection multiplier. It addresses the different topic BFD detection multiplier and negotiated timers, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: Validate a wireless user VLAN pool and its DHCP scope availability when client addressing becomes uneven or fails under density. It addresses the different topic WLAN VLAN pools and DHCP address scopes, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

This option proposes: Differentiate traffic policy-based routing on a matching packet from ordinary destination-based forwarding through the best RIB route. It addresses the different topic Policy-based routing versus destination routing, not the directly tested Multicast reverse path forwarding checks failure in the stated incident (A network migrates PIM uplinks yet retains stale unicast routes toward the multicast source, causing intermittent RPF failures.).

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 IGMP querier membership reports and group timeout failure in the stated incident (A floor switch has active IPTV receivers, but multicast stops after its IGMP querier leaves and group records age out.).

This option proposes: Diagnose a multicast drop by checking reverse path forwarding against the packet's source rather than only validating the destination group. It addresses the different topic Multicast reverse path forwarding checks, not the directly tested IGMP querier membership reports and group timeout failure in the stated incident (A floor switch has active IPTV receivers, but multicast stops after its IGMP querier leaves and group records age out.).

This option proposes: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations. It addresses the different topic OSPF router network and summary LSA scope, not the directly tested IGMP querier membership reports and group timeout failure in the stated incident (A floor switch has active IPTV receivers, but multicast stops after its IGMP querier leaves and group records age out.).

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 IGMP querier membership reports and group timeout failure in the stated incident (A floor switch has active IPTV receivers, but multicast stops after its IGMP querier leaves and group records age out.).

This option proposes: SNMP managers request device state, while traps and informs carry event notifications; SNMPv3 offers user-based authentication and optional privacy protection unlike insecure shared-community assumptions. It addresses the different topic SNMP manager polling traps and authenticated operation, not the directly tested IGMP querier membership reports and group timeout failure in the stated incident (A floor switch has active IPTV receivers, but multicast stops after its IGMP querier leaves and group records age out.).

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 IGMP querier membership reports and group timeout failure in the stated incident (A floor switch has active IPTV receivers, but multicast stops after its IGMP querier leaves and group records age out.).