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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 broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

This option proposes: VRRP uses a virtual router identity and virtual MAC per IPv4 group to preserve a stable next-hop identity across master changes; correct failover still requires matching VLAN, neighbor learning and eligible router state. It addresses the different topic VRRP virtual MAC and endpoint ARP continuity, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

This option proposes: OSPF's intra-area SPF calculation prefers the lowest valid accumulated link cost, subject to equal-cost rules; a protocol neighbor being Full alone does not establish path preference. It addresses the different topic OSPF SPF calculation and interface cost changes, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

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 broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

This option proposes: Compare LSP identifiers, sequence numbers, aging, CSNP summaries, PSNP entries and adjacency state on the affected circuit. It addresses the different topic IS-IS LSP synchronization using CSNP and PSNP, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

This option proposes: Check whether the interface should form neighbors, its authentication mode, passive state, advertised prefix and neighboring device visibility. It addresses the different topic OSPF interface security and passive network advertisement, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

That option concerns OSPF backbone connectivity and virtual link design. That follows from the targeted action: Review broadcast-network designated-router election based on interface priority and router ID, noting that a stable election does not automatically preempt.

That option concerns OSPF router network and summary LSA scope. That follows from the targeted action: Review broadcast-network designated-router election based on interface priority and router ID, noting that a stable election does not automatically preempt.

That option concerns Wireless roaming mobility and session continuity. That follows from the targeted action: Review broadcast-network designated-router election based on interface priority and router ID, noting that a stable election does not automatically preempt.

This option proposes: Enable OSPF neighbor formation on an untrusted user access VLAN because route advertisement is presumed impossible without forming user-device adjacencies. It addresses the different topic OSPF interface security and passive network advertisement, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

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 broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

This option proposes: Build an OSPF virtual link through a stub transit area and assume the special-area flag has no influence on its eligibility. It addresses the different topic OSPF backbone connectivity and virtual link design, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A switch segment receives a new OSPF speaker with a high priority, but its dashboard still shows the long-running designated router.).

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 broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Choose the appropriate enterprise datacom architecture for a campus user edge versus a scalable data-center fabric before selecting a particular routing or switching feature. It addresses the different topic Campus design versus data center fabric operational boundaries, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Compare OSPF interface state, area, authentication, timers and network type before resetting a neighbor relationship. It addresses the different topic OSPF adjacency prerequisites and mismatched parameters, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: MQC policy operation separates traffic classifiers, traffic behaviors and policies that bind them on a supported interface and direction; defining a classifier by itself does not apply a traffic action. It addresses the different topic Huawei MQC traffic classification and behavior binding, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

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 broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: An NSSA permits its local ASBR to originate type 7 external LSAs that can be translated to type 5 by an eligible ABR, while incoming external type 5 advertisements are not flooded into the NSSA. It addresses the different topic NSSA type seven translation and default routing, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Map the ABRs, area membership, transit-area properties and database synchronization along the proposed virtual-link path. It addresses the different topic OSPF backbone connectivity and virtual link design, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Compare the area link-state database, LSA type, advertising router, ABR reachability and route installation for the absent prefix. It addresses the different topic OSPF router network and summary LSA scope, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Inspect local and remote BFD configured minima, actual negotiated intervals, multiplier values, CPU pressure and observed detection timestamps. It addresses the different topic BFD detection multiplier and negotiated timers, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

That option concerns OSPF interface security and passive network advertisement. That follows from the targeted Recommended action: Review broadcast-network designated-router election based on interface priority and router ID, noting that a stable election does not automatically preempt.

That option concerns DHCP relay across a routed user VLAN. That follows from the targeted Recommended action: Review broadcast-network designated-router election based on interface priority and router ID, noting that a stable election does not automatically preempt.

That option concerns NSSA type seven translation and default routing. That follows from the targeted Recommended action: Review broadcast-network designated-router election based on interface priority and router ID, noting that a stable election does not automatically preempt.

This option proposes: Configure VRRP priority tracking with suitable preemption behavior so loss of upstream connectivity changes the preferred gateway. It addresses the different topic VRRP interface tracking and controlled preemption, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Diagnose a packet-forwarding discrepancy by separating control-plane routes recorded in the RIB from hardware or software forwarding entries installed in the FIB. It addresses the different topic Network forwarding planes RIB versus FIB, not the directly tested OSPF broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

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 broadcast DR and BDR election failure in the stated incident (A network engineer sets one interface's OSPF priority to zero and is surprised that the router no longer qualifies for DR or BDR election.).

This option proposes: Ensure consistent MST region name, revision and VLAN-to-instance mapping before expecting switches to share the same spanning-tree instance topology. It addresses the different topic MSTP region and VLAN-to-instance mappings, 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: Diagnose an unexpected OSPF intra-area path by comparing cumulative interface costs through the shortest-path tree. 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: 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 (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: 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.).