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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 BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Use AS_PATH to reason about external route propagation, loop prevention and intentional prepending effects. It addresses the different topic BGP AS_PATH path-vector loop prevention, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Use Bidirectional Forwarding Detection to provide rapid validated failure indications to a supported routing or redundancy protocol. It addresses the different topic BFD rapid session detection and routing protocol association, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Large WLAN deployments can distribute users among VLANs with a VLAN pool, but every selected VLAN still needs the correct gateway, DHCP scope and forwarding path to support client sessions. It addresses the different topic WLAN VLAN pools and DHCP address scopes, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: BGP communities carry policy markers that can be matched by participating peers, but the markers alone do not enforce filtering unless suitable route-policy rules recognize and act on them. It addresses the different topic BGP community tagging and route-policy control, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: A BGP network statement generally requires an appropriate matching route in the local routing table, whereas importing routes from other protocols uses an explicit redistribution mechanism; export policy can further restrict announcements. It addresses the different topic BGP route origin network and redistribution policy, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Inspect candidate routes' neighboring AS, MED values, other higher-priority attributes and local comparison configuration. It addresses the different topic BGP MED interpretation between neighboring autonomous systems, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Compare received EVPN route type, route target/import rules, VNI mapping, VTEP addresses and underlay route resolution. It addresses the different topic MP-BGP EVPN route types and forwarding separation, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Compare traffic patterns, device role, access-layer services, user or workload segmentation, resiliency goals and the underlying control-plane topology. It addresses the different topic Campus design versus data center fabric operational boundaries, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

That option concerns OSPF external LSAs and E1 versus E2 cost. That follows from the targeted Recommended action: Diagnose outbound path choice across iBGP speakers using locally distributed LOCAL_PREF values.

This option proposes: Looping advertisements are rejected and intended route preference changes are explained without promising a universal AS_PATH outcome. It addresses the different topic BGP AS_PATH path-vector loop prevention, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.). The better discriminating check for this case is: Compare received iBGP routes to the same prefix, LOCAL_PREF values, policy application points and next-hop reachability across edge routers. The targeted correction is: Diagnose outbound path choice across iBGP speakers using locally distributed LOCAL_PREF values.

That option concerns BGP community tagging and route-policy control. That follows from the targeted Recommended action: Diagnose outbound path choice across iBGP speakers using locally distributed LOCAL_PREF values.

This option proposes: Diagnose RSTP forwarding state by identifying root, designated and alternate ports and the topology's point-to-point characteristics. It addresses the different topic RSTP port roles and rapid convergence, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Calculate or verify the practical failure-detection threshold from BFD transmit intervals, advertised receive intervals and the detect multiplier. It addresses the different topic BFD detection multiplier and negotiated timers, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Inspect the active RIB prefix and mask, BGP network or import-route configuration, route-policy matches and outbound Adj-RIB-Out to the peer. It addresses the different topic BGP route origin network and redistribution policy, not the directly tested BGP LOCAL_PREF within one autonomous system failure in the stated incident (After a route-policy change, one branch prefers a backup transit router even though the core's intended LOCAL_PREF for the main exit is higher.).

This option proposes: Investigate a BGP route that appears in a peer table but fails to install because its NEXT_HOP is unresolved. It addresses the different topic BGP NEXT_HOP reachability and next-hop-self, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

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 BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: Use standard BGP communities and import/export policy to label route groups and apply intended traffic-engineering behavior. It addresses the different topic BGP community tagging and route-policy control, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: BFD failure detection depends on negotiated receive intervals and a multiplier, so unrealistically aggressive values can cause transient congestion or scheduler delays to trigger unnecessary session-down events. It addresses the different topic BFD detection multiplier and negotiated timers, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: BGP path validity requires next-hop reachability; iBGP may preserve an eBGP-learned next hop, so a next-hop-self design can make that address reachable through the IGP where appropriate. It addresses the different topic BGP NEXT_HOP reachability and next-hop-self, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: BGP AS_PATH records traversed autonomous systems, and an eBGP router ordinarily rejects a received route containing its own AS; prepending the local AS can influence some external path decisions but does not override every selection policy. It addresses the different topic BGP AS_PATH path-vector loop prevention, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: Examine the level-1 and level-2 routing tables, leak policy, LSP overload flags and route next hops before modifying metric preferences. It addresses the different topic IS-IS routing leakage and overload bit, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

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 BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

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 BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.). The better discriminating check for this case is: Inspect candidate routes' neighboring AS, MED values, other higher-priority attributes and local comparison configuration. The targeted correction is: Check the MED value and the policy context before using BGP advertisements to suggest which entry link another AS should prefer.

This option proposes: Looping advertisements are rejected and intended route preference changes are explained without promising a universal AS_PATH outcome. It addresses the different topic BGP AS_PATH path-vector loop prevention, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.). The better discriminating check for this case is: Inspect candidate routes' neighboring AS, MED values, other higher-priority attributes and local comparison configuration. The targeted correction is: Check the MED value and the policy context before using BGP advertisements to suggest which entry link another AS should prefer.

That option concerns OSPF router network and summary LSA scope. That follows from the targeted action: Check the MED value and the policy context before using BGP advertisements to suggest which entry link another AS should prefer.

That option concerns BGP community tagging and route-policy control. That follows from the targeted action: Check the MED value and the policy context before using BGP advertisements to suggest which entry link another AS should prefer.

This option proposes: Override all AS loop checks because a longer AS_PATH is said to be universally more attractive to every external BGP neighbor. It addresses the different topic BGP AS_PATH path-vector loop prevention, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: Attempt to manipulate a remote ISP's outbound path by expecting an internal LOCAL_PREF value to be automatically carried over eBGP advertisements. It addresses the different topic BGP LOCAL_PREF within one autonomous system, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: Attempt to configure an OSPF BDR role for IS-IS, assuming the DIS cannot operate until a backup DIS has been selected. It addresses the different topic IS-IS designated intermediate system and pseudonode, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A carrier offers two circuits between the same pair of ASes and asks which MED values would express a preferred inbound entry.).

This option proposes: Use AS_PATH to reason about external route propagation, loop prevention and intentional prepending effects. It addresses the different topic BGP AS_PATH path-vector loop prevention, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A multihomed company sets the same MED on both uplinks but observes traffic asymmetry caused by its partner's local routing policy.).

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 BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A multihomed company sets the same MED on both uplinks but observes traffic asymmetry caused by its partner's local routing policy.).

This option proposes: Apply route-reflector client roles and loop-prevention attributes to an iBGP topology that must scale beyond a full mesh. It addresses the different topic BGP route reflector and cluster loop prevention, not the directly tested BGP MED interpretation between neighboring autonomous systems failure in the stated incident (A multihomed company sets the same MED on both uplinks but observes traffic asymmetry caused by its partner's local routing policy.).