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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 IPv6 neighbor discovery NS NA and address resolution failure in the stated incident (An operator sees a reachable IPv4 gateway and assumes IPv6 address resolution must work despite no Neighbor Advertisement from the IPv6 router.).

This option proposes: Review RA source, autonomous prefix flag, valid and preferred lifetimes, DAD NS traffic, address state and default router list. It addresses the different topic IPv6 SLAAC RA prefix and duplicate address detection, not the directly tested IPv6 neighbor discovery NS NA and address resolution failure in the stated incident (An operator sees a reachable IPv4 gateway and assumes IPv6 address resolution must work despite no Neighbor Advertisement from the IPv6 router.). The better discriminating check for this case is: Inspect neighbor cache states, NS/NA exchanges, solicited-node multicast, router advertisements and link-layer addresses on the affected VLAN.

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 IPv6 neighbor discovery NS NA and address resolution failure in the stated incident (An operator sees a reachable IPv4 gateway and assumes IPv6 address resolution must work despite no Neighbor Advertisement from the IPv6 router.).

This option proposes: Investigate IPv6 neighbor resolution using ICMPv6 Neighbor Solicitation and Neighbor Advertisement rather than IPv4 ARP assumptions. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: Assess fast roaming within and between AP coverage cells using the configured mobility relationship and authentication requirements. It addresses the different topic Wireless roaming mobility and session continuity, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: Check route-policy matching conditions, node permit/deny behavior and application direction before fixing unexpected accepted or rejected routes. It addresses the different topic Route-policy node and filtering direction, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: IPv6 Neighbor Discovery uses ICMPv6 control messages for local-link address resolution and reachability; solicited-node multicast and link-local addressing are essential to the mechanism, and ARP is not used by IPv6. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: SDN-based WAN management centralizes policy orchestration and visibility, while SD-WAN forwarding uses measured underlay links and application or SLA policies to choose paths; controller reachability alone does not guarantee user traffic meets latency targets. It addresses the different topic SDN WAN control and SD-WAN policy forwarding, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: IGMP reports express receiver interest in multicast groups and a querier maintains group membership state; without appropriate reports or queries a router can age out forwarding toward a segment. It addresses the different topic IGMP querier membership reports and group timeout, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: Review packet source and destination fields, rule sequence, actual interface ingress or egress attachment and matching counters. It addresses the different topic ACL traffic filter placement and rule order, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: Compare WLAN service templates, VLAN pool membership and assignment method, gateway/SVI, relay configuration and per-VLAN available leases. It addresses the different topic WLAN VLAN pools and DHCP address scopes, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: Inspect neighbor cache states, NS/NA exchanges, solicited-node multicast, router advertisements and link-layer addresses on the affected VLAN. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

That option concerns Huawei firewall NAT and address translation context. That follows from the targeted action: Validate IPv6 router advertisements, prefix information and duplicate-address detection before treating a newly generated address as usable.

That option concerns RSTP port roles and rapid convergence. That follows from the targeted action: Validate IPv6 router advertisements, prefix information and duplicate-address detection before treating a newly generated address as usable.

This option proposes: The host resolves the correct IPv6 neighbor and reaches its default router without relying on IPv4 ARP packets. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (New campus laptops display tentative IPv6 addresses for an extended period because DAD solicitation responses reveal collisions in a cloned address scheme.).

This option proposes: Separate any-source group subscriptions from IGMPv3 source-specific multicast membership when implementing an SSM service. It addresses the different topic IGMPv3 source-specific selection and SSM, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

This option proposes: Investigate IPv6 neighbor resolution using ICMPv6 Neighbor Solicitation and Neighbor Advertisement rather than IPv4 ARP assumptions. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

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 IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

This option proposes: IPv6 Neighbor Discovery uses ICMPv6 control messages for local-link address resolution and reachability; solicited-node multicast and link-local addressing are essential to the mechanism, and ARP is not used by IPv6. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

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 IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

This option proposes: Passive OSPF interfaces can stop unwanted neighbor discovery while their connected networks may still be advertised through the OSPF process; authentication protects routing exchanges and requires compatible peer settings. It addresses the different topic OSPF interface security and passive network advertisement, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

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 IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

This option proposes: Inspect neighbor cache states, NS/NA exchanges, solicited-node multicast, router advertisements and link-layer addresses on the affected VLAN. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

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 IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

That option concerns Network device AAA role SSH and management-plane protection. That follows from the targeted Recommended action: Validate IPv6 router advertisements, prefix information and duplicate-address detection before treating a newly generated address as usable.

This option proposes: The selected BGP prefix has a resolvable next hop and traffic exits through the intended edge after the appropriate next-hop policy. It addresses the different topic BGP NEXT_HOP reachability and next-hop-self, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.). The better discriminating check for this case is: Review RA source, autonomous prefix flag, valid and preferred lifetimes, DAD NS traffic, address state and default router list. The targeted correction is: Validate IPv6 router advertisements, prefix information and duplicate-address detection before treating a newly generated address as usable.

This option proposes: The host resolves the correct IPv6 neighbor and reaches its default router without relying on IPv4 ARP packets. It addresses the different topic IPv6 neighbor discovery NS NA and address resolution, not the directly tested IPv6 SLAAC RA prefix and duplicate address detection failure in the stated incident (A router advertises an IPv6 prefix without the appropriate autonomous flag and clients do not autoconfigure addresses as the administrator expected.).

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 Stateful firewall sessions versus basic packet ACL filtering failure in the stated incident (A corporate user initiates HTTPS through a firewall but receives no response after an asymmetric route sends return traffic to a different inspection path.).

This option proposes: Troubleshoot a site-to-site IPsec tunnel by separating IKE security-association establishment from protected ESP payload transport. It addresses the different topic IPsec VPN IKE negotiation versus ESP data channel, not the directly tested Stateful firewall sessions versus basic packet ACL filtering failure in the stated incident (A corporate user initiates HTTPS through a firewall but receives no response after an asymmetric route sends return traffic to a different inspection path.).

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 Stateful firewall sessions versus basic packet ACL filtering failure in the stated incident (A corporate user initiates HTTPS through a firewall but receives no response after an asymmetric route sends return traffic to a different inspection path.).

This option proposes: AAA separates authentication, authorization and accounting for device management, while SSH protects management sessions and access policies can limit trusted administrative sources. It addresses the different topic Network device AAA role SSH and management-plane protection, not the directly tested Stateful firewall sessions versus basic packet ACL filtering failure in the stated incident (A corporate user initiates HTTPS through a firewall but receives no response after an asymmetric route sends return traffic to a different inspection path.).

This option proposes: IKE negotiates security associations and authenticates peers, while IPsec ESP carries encrypted or integrity-protected traffic as configured; matching peer identities, proposals and traffic selectors are needed for an effective tunnel. It addresses the different topic IPsec VPN IKE negotiation versus ESP data channel, not the directly tested Stateful firewall sessions versus basic packet ACL filtering failure in the stated incident (A corporate user initiates HTTPS through a firewall but receives no response after an asymmetric route sends return traffic to a different inspection path.).

This option proposes: WLAN roaming is a client transition between APs, and preserving service depends on consistent SSID/security configuration, mobility coordination and the chosen network architecture, not simply RF overlap. It addresses the different topic Wireless roaming mobility and session continuity, not the directly tested Stateful firewall sessions versus basic packet ACL filtering failure in the stated incident (A corporate user initiates HTTPS through a firewall but receives no response after an asymmetric route sends return traffic to a different inspection path.).