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This option proposes: OSPF neighbors on a common link must agree on critical adjacency parameters, including compatible area and authentication; repeated resets will not repair a persistent mismatch. It addresses the different topic OSPF adjacency prerequisites and mismatched parameters, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

This option proposes: NAT rules change observed packet addresses under defined conditions, and a permitted security rule alone does not create a suitable translation mapping or solve upstream return routing. It addresses the different topic Huawei firewall NAT and address translation context, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

This option proposes: On a broadcast network OSPF uses a DR and BDR to limit adjacency overhead; priority zero excludes a candidate, and higher eligible priority and router ID influence a new election rather than forcing instant replacement of a functioning DR. It addresses the different topic OSPF broadcast DR and BDR election, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

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 OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

This option proposes: Inspect OSPF neighbor states and interface detail on both ends, including area IDs, hello/dead intervals, network type and authentication settings. It addresses the different topic OSPF adjacency prerequisites and mismatched parameters, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

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 OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

That option concerns OSPF broadcast DR and BDR election. That follows from the targeted action: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations.

That option concerns Huawei MQC traffic classification and behavior binding. That follows from the targeted action: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations.

That option concerns OSPF backbone connectivity and virtual link design. That follows from the targeted action: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations.

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 OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

This option proposes: Distinguish EVPN control-plane route information and underlay forwarding when analyzing a VXLAN-enabled fabric. It addresses the different topic MP-BGP EVPN route types and forwarding separation, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

This option proposes: Compare each candidate path's per-interface costs, SPF route metrics, topology database and resulting next-hop entries. It addresses the different topic OSPF SPF calculation and interface cost changes, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (A branch in area 20 can see its local type 1 topology but no type 3 summary for a corporate data-center prefix in area 0.).

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 OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Check OSPF area type before attempting to import external routes into an area intended to suppress route detail. It addresses the different topic Stub and totally stub area restrictions, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Verify NSSA area behavior and type 7-to-type 5 translation when redistributing an external prefix inside a non-backbone area. It addresses the different topic NSSA type seven translation and default routing, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Huawei ACL filtering considers rule order and match criteria; permit or deny decisions depend on the traffic-filter feature and where the ACL is applied, so a symmetric assumption about directions can be wrong. It addresses the different topic ACL traffic filter placement and rule order, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Inter-area OSPF design relies on a connected backbone area; virtual links can logically connect certain disconnected backbone segments through a suitable transit area but cannot pass through a stub area. It addresses the different topic OSPF backbone connectivity and virtual link design, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: A stub area blocks type 5 external LSAs and receives an appropriate default through its ABR; a totally stubby configuration additionally suppresses most inter-area summaries and is incompatible with certain topology roles. It addresses the different topic Stub and totally stub area restrictions, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Trace the NSSA ASBR's type 7 LSA, translator ABR status, resulting type 5 advertisement outside the area and any intentionally configured default. It addresses the different topic NSSA type seven translation and default routing, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Inspect route-reflector client configuration, ORIGINATOR_ID, CLUSTER_LIST and resulting prefixes at different iBGP clients. It addresses the different topic BGP route reflector and cluster loop prevention, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Inspect the summarization boundary, contributing active component prefixes, aggregate advertisement and forwarding toward the actual destinations. It addresses the different topic OSPF summarization at ABR and ASBR, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

That option concerns OSPF interface security and passive network advertisement. That follows from the targeted Recommended action: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations.

That option concerns BFD rapid session detection and routing protocol association. That follows from the targeted Recommended action: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations.

That option concerns OSPF backbone connectivity and virtual link design. That follows from the targeted Recommended action: Identify OSPF LSA types and their flooding scope before diagnosing missing intra-area or inter-area destinations.

This option proposes: Configure a stub area on only one side of an OSPF adjacency and insist that an external type 5 LSA must cross that boundary unchanged. It addresses the different topic Stub and totally stub area restrictions, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Assume a router must forward every packet sent to a multicast group whenever it has a unicast default route, regardless of the packet's incoming interface. It addresses the different topic Multicast reverse path forwarding checks, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Force every router to restart its OSPF process after discovering mismatched hello intervals, without first correcting the link configuration. It addresses the different topic OSPF adjacency prerequisites and mismatched parameters, not the directly tested OSPF router network and summary LSA scope failure in the stated incident (During a design review a specialist mistakenly expects a transit area's network LSA to be copied unchanged into every non-backbone area.).

This option proposes: Verify NSSA area behavior and type 7-to-type 5 translation when redistributing an external prefix inside a non-backbone area. It addresses the different topic NSSA type seven translation and default routing, not the directly tested OSPF external LSAs and E1 versus E2 cost failure in the stated incident (A dual-exit enterprise redistributes the same external prefix at two ASBRs and sees traffic prefer one exit despite different internal path costs.).

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 OSPF external LSAs and E1 versus E2 cost failure in the stated incident (A dual-exit enterprise redistributes the same external prefix at two ASBRs and sees traffic prefer one exit despite different internal path costs.).

This option proposes: Verify BGP network origination and import-route mechanisms before expecting a prefix to be advertised. It addresses the different topic BGP route origin network and redistribution policy, not the directly tested OSPF external LSAs and E1 versus E2 cost failure in the stated incident (A dual-exit enterprise redistributes the same external prefix at two ASBRs and sees traffic prefer one exit despite different internal path costs.).

This option proposes: Type 1 router and type 2 network LSAs describe area-local topology, whereas ABRs create type 3 summary LSAs for destinations in other areas; a lack of appropriate LSAs affects SPF reachability. It addresses the different topic OSPF router network and summary LSA scope, not the directly tested OSPF external LSAs and E1 versus E2 cost failure in the stated incident (A dual-exit enterprise redistributes the same external prefix at two ASBRs and sees traffic prefer one exit despite different internal path costs.).

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 OSPF external LSAs and E1 versus E2 cost failure in the stated incident (A dual-exit enterprise redistributes the same external prefix at two ASBRs and sees traffic prefer one exit despite different internal path costs.).

This option proposes: Inter-area OSPF design relies on a connected backbone area; virtual links can logically connect certain disconnected backbone segments through a suitable transit area but cannot pass through a stub area. It addresses the different topic OSPF backbone connectivity and virtual link design, not the directly tested OSPF external LSAs and E1 versus E2 cost failure in the stated incident (A dual-exit enterprise redistributes the same external prefix at two ASBRs and sees traffic prefer one exit despite different internal path costs.).