Cisco 300-420 Bundle

Link redundancy within the fabric does not guarantee sufficient external border forwarding capacity during degraded operation. “Size border nodes and redundant exits for N-minus-one load, applying failure-domain and traffic-engineering requirements” would remedy that alternative situation, but it would not correct the present issue: stateful inspection needs coherent bidirectional flow visibility, while independent routing cost choices can create asymmetric paths.

“Tie aggregate advertisement to required downstream reachability or redesign summarization and redundancy accordingly” is the supported response when a summary advertised by a border without valid components can attract and blackhole traffic during partial network failures. Here the decisive response is “Select a topology and route policy that maintain suitable symmetric inspected paths or supported state sharing”, so that different intervention does not meet the stated requirement.

Physical redundancy does not imply control-plane equal-cost path installation or useful flow distribution. “Align appropriate IGP costs and supported equal-cost multipath settings with capacity and symmetric path requirements” applies to that other condition. The reported evidence is a campus distribution redesign installs a stateful firewall on one inter-building path while a lower-cost IGP return route bypasses that firewall; this alternative would address the wrong dependency.

Identity group classification requires a trusted policy source and onboarding process rather than arbitrary address-based role guessing. “Integrate the fabric with appropriate Cisco ISE identity policy and validated endpoint profiling or authentication flows” would remedy that alternative situation, but it would not correct the present issue: a single endpoint map/control-plane service is a common-mode availability risk even with redundant data-plane links.

“Select a supported SD-Access multicast forwarding model and test receivers across fabric edges and virtual networks” is the supported response when fabric overlay multicast support and replication design have specific control and data-plane requirements beyond simple underlay multicast reachability. Here the decisive response is “Design supported control-plane node redundancy and test endpoint registration continuity during node loss”, so that different intervention does not meet the stated requirement.

Security group policy alone may not replace full virtual-network level route isolation where separate macrosegments are required. “Design distinct fabric virtual networks with appropriate external borders and tightly defined shared services” applies to that other condition. The reported evidence is a campus fabric has one control-plane node that maintains all endpoint registrations, and a planned node upgrade makes roaming users unreachable; this alternative would address the wrong dependency.

That change concerns dmvpn spoke to spoke optimization, where A purely hub-and-spoke forwarding policy can add latency and load when the DMVPN design is intended to allow direct spoke shortcuts. The reported issue instead stems from: Dynamic spoke resolution needs correct NHRP network ID, authentication, hub mapping and reachable tunnel source rather than only a live Internet connection.

That change concerns ipsec encryption versus gre transport, where GRE provides encapsulation for multiple protocols but does not itself encrypt or authenticate payload confidentiality. In this question the necessary remedy is “Align supported NHRP and tunnel registration settings and verify the hub can map the spoke's current public transport address”, which this alternative does not provide.

That change concerns cloud wan direct private connectivity choice, where An encrypted Internet overlay does not provide the same private carrier connectivity, SLA and traffic-engineering options as a qualified dedicated cloud circuit. The observed condition is after replacing a branch Internet router, its DMVPN tunnel interface can reach the public network but the spoke no longer appears as registered at the hub; this mechanism addresses another problem.

A virtualized or stacked switching design needs supported control, state and multichassis link mechanisms to act as one logical system. “Select a validated stacking or virtual-switch architecture and plan supervisor, interconnect and software compatibility” would remedy that alternative situation, but it would not correct the present issue: physical redundancy does not imply control-plane equal-cost path installation or useful flow distribution.

“Tie aggregate advertisement to required downstream reachability or redesign summarization and redundancy accordingly” is the supported response when a summary advertised by a border without valid components can attract and blackhole traffic during partial network failures. Here the decisive response is “Align appropriate IGP costs and supported equal-cost multipath settings with capacity and symmetric path requirements”, so that different intervention does not meet the stated requirement.

Unfiltered inter-VRF route leaking can undermine segmentation even if each tenant has its own routing instance. “Export only authorized service prefixes and apply necessary packet access restrictions at the shared-services border” applies to that other condition. The reported evidence is two equal-bandwidth routed building uplinks are available but all flows pass one link because IGP costs and ECMP eligibility were not considered; this alternative would address the wrong dependency.

Translation adds stateful dependencies and application edge cases that may be unnecessary when a controlled native dual-stack phase is viable. “Select native dual stack for capable segments and reserve translation for real IPv4-only boundaries with documented requirements” would remedy that alternative situation, but it would not correct the present issue: internal OSPF cost does not communicate an intended interconnect preference to the neighboring autonomous system.

“Set governed BGP local preference on inbound routes from the preferred provider, with consistent internal propagation” is the supported response when AS-path prepending mainly affects remote path selection; outbound path preference within the local AS is commonly controlled with local preference. Here the decisive response is “Use supported BGP MED where appropriate, coordinate the provider's comparison behavior and keep resilient alternate exits”, so that different intervention does not meet the stated requirement.

IBGP typically preserves the external next hop, which must be reachable through the internal routing infrastructure. “Provide appropriate next-hop-self policy or valid internal reachability for external BGP next hops with loop-free forwarding” applies to that other condition. The reported evidence is a corporation connects twice to one upstream AS and wants to suggest a preferred entry point to that neighbor, yet edits only routing metrics inside its own OSPF core; this alternative would address the wrong dependency.

External Type 2 cost behavior does not account for internal cost in the same way as Type 1 when external metrics differ. “Document OSPF external metric type as part of every redistribution design review” would remedy that alternative situation, but it would not correct the present issue: a totally stubby or regular stub area cannot originate external LSAs through an internal ASBR in the required manner.

“Review area stub restrictions and ASBR needs before switching any area type” is the supported response when a normal area floods external routing information that stub-capable branches may not need when a default route is sufficient. Here the decisive response is “Verify NSSA translation and ABR failover when adding local redistribution at a stub-like branch”, so that different intervention does not meet the stated requirement.

A fragmented area-address plan and missing ABR inter-area summarization cause avoidable detailed LSAs to propagate. “Keep OSPF area allocation aligned with IPAM aggregation boundaries across expansion projects” applies to that other condition. The reported evidence is a remote OSPF branch must inject routes from a local non-OSPF process while still limiting external flooding from the rest of the enterprise; this alternative would address the wrong dependency.

That change concerns BGP prefix filter outbound boundary, where Unrestricted BGP export policy exposes destinations not authorized for upstream announcement and risks routing leaks. The reported issue instead stems from: IPv6-only clients cannot communicate with IPv4-only services without supported translation and suitable destination synthesis.

That change concerns ipv6 overlay mtu and pmtud, where Overlay headers reduce usable path MTU and blocked ICMPv6 Packet Too Big feedback can prevent Path MTU Discovery. In this question the necessary remedy is “Design appropriate NAT64 plus DNS64 service boundaries, DNS behavior and application compatibility exceptions”, which this alternative does not provide.

That change concerns ipv6 dual stack versus translation cost, where Translation adds stateful dependencies and application edge cases that may be unnecessary when a controlled native dual-stack phase is viable. The observed condition is a company deploys IPv6-only client VLANs that must reach legacy IPv4-only APIs, but assumes routing IPv6 packets directly to IPv4 server addresses is possible; this mechanism addresses another problem.

An IPv4-only underlay cannot natively carry IPv6 forwarding without an overlay or other transition capability. “Monitor tunnel endpoint resilience and account for encapsulation overhead in path MTU design” would remedy that alternative situation, but it would not correct the present issue: BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic.

“Govern community naming, collision avoidance and route-leak tests across all border routers” is the supported response when manual per-prefix policy misses newly onboarded routes when attributes and export rules are not centrally classified. Here the decisive response is “Reassess multipath qualification whenever route attributes, providers or platform software change”, so that different intervention does not meet the stated requirement.

Graceful restart depends on both peers' supported capabilities and bounded stale-route handling, not merely a routing session name. “Test graceful-restart interactions with BFD and forwarding readiness during platform changes” applies to that other condition. The reported evidence is an edge device has two BGP paths to the same prefix but operators expect load sharing merely because both routes appear in the neighbor table; this alternative would address the wrong dependency.

Ordinary port-level upgrades may not meet aggregate fiber-capacity and distance requirements when the optical transport must host many independent wavelengths. “Evaluate supported DWDM wavelengths, optics, optical budget, dispersion and protection channels for the transport design” would remedy that alternative situation, but it would not correct the present issue: n-minus-one operation cannot carry combined load if each remaining link lacks spare capacity or business traffic prioritization.

“Choose appropriate low-latency WAN transport and QoS treatment, evaluating cost, resilience and route diversity” is the supported response when bandwidth alone does not determine application suitability when propagation delay and jitter exceed interactive service limits. Here the decisive response is “Size redundant WAN capacity for failure-state critical loads or design explicit congestion and traffic-class degradation policy”, so that different intervention does not meet the stated requirement.

Multihoming and address translation must account for both directions; outbound route changes alone may not preserve return paths. “Design consistent BGP advertisement, NAT and routing failover so return flows follow the reachable secondary path” applies to that other condition. The reported evidence is two regional WAN links each run at eighty percent peak utilization, but design documents promise full service during loss of either one; this alternative would address the wrong dependency.

Fabric overlay multicast support and replication design have specific control and data-plane requirements beyond simple underlay multicast reachability. “Select a supported SD-Access multicast forwarding model and test receivers across fabric edges and virtual networks” would remedy that alternative situation, but it would not correct the present issue: unfiltered inter-VRF route leaking can undermine segmentation even if each tenant has its own routing instance.

“Tie aggregate advertisement to required downstream reachability or redesign summarization and redundancy accordingly” is the supported response when a summary advertised by a border without valid components can attract and blackhole traffic during partial network failures. Here the decisive response is “Export only authorized service prefixes and apply necessary packet access restrictions at the shared-services border”, so that different intervention does not meet the stated requirement.

High session counts and excessively aggressive timers can exhaust control resources and cause false routing flaps. “Model required convergence classes and scale BFD deployment selectively on critical routed interfaces” applies to that other condition. The reported evidence is a guest campus VRF is permitted to reach a shared DNS service but a broad route leak accidentally exposes internal management subnets; this alternative would address the wrong dependency.

Using only the affected data-plane overlay for operational access can eliminate remote troubleshooting when the fabric fails. “Provide an appropriately secured independent management path or out-of-band recovery access for critical WAN edges” would remedy that alternative situation, but it would not correct the present issue: an MPLS Layer 3 VPN routes IP among separated CE networks rather than delivering a transparent Layer 2 Ethernet service.

“Select a supported MPLS L3VPN design using separate VPN routing tables and approved route-target import/export policy” is the supported response when a shared provider routing domain cannot preserve independent overlapping tenant address spaces and route targets without isolation. Here the decisive response is “Choose an eligible provider Layer 2 VPN or Ethernet private line design if extending a broadcast domain is genuinely required”, so that different intervention does not meet the stated requirement.

Mobile backup is useful only if real coverage, policy, cost and failure independence support required branch services. “Design cellular failover with tested signal strength, provider diversity, data-plan capacity and selective critical traffic routing” applies to that other condition. The reported evidence is a retailer wants two facilities to operate on one Ethernet broadcast domain across a managed provider network, but its proposed ordinary routed MPLS L3VPN does not transport Ethernet frames; this alternative would address the wrong dependency.