Cisco 300-420 Bundle

That change concerns rapid spanning tree edge port guard, where Unprotected edge-port fast transition can introduce topology-change or loop risks if another bridge is attached. The reported issue instead stems from: Routing graceful restart requires compatible neighbor capability and safe stale-route lifetimes, not merely redundant uplinks.

That change concerns campus stp root placement, where Without deliberate STP root design, Layer 2 forwarding paths may traverse inappropriate access hardware. In this question the necessary remedy is “Use supported graceful restart and nonstop forwarding features only where peer compatibility and forwarding state can be verified”, which this alternative does not provide.

That change concerns campus virtual switching platform abstraction, where A virtualized or stacked switching design needs supported control, state and multichassis link mechanisms to act as one logical system. The observed condition is a campus core undergoes control-plane restart and peers immediately purge all routes although forwarding hardware might remain functional during a supported restart interval; this mechanism addresses another problem.

Uncontrolled multihoming can select unpredictable exits and cause asymmetry or suboptimal paths under provider changes. “Define local preference, inbound announcement policy and health tracking based on primary and backup business requirements” would remedy that alternative situation, but it would not correct the present issue: remote-only controller dependencies and insufficient regional capacity can degrade onboarding, resiliency and convergence at scale.

“Design approved branch egress security with local firewall, cloud security service or appropriate service chaining” is the supported response when local breakout bypasses central inspection unless equivalent secure edge controls and policy are deliberately placed. Here the decisive response is “Design supported regional controller and overlay architecture with redundancy, policy consistency and documented capacity limits”, so that different intervention does not meet the stated requirement.

Naive unicast replication can consume excessive WAN capacity, while multicast support depends on platform and overlay design. “Choose a supported multicast distribution and replication approach with measured receiver count and transport constraints” applies to that other condition. The reported evidence is a global SD-WAN fabric grows across continents but keeps every edge tied to a distant single control region, causing instability during regional carrier outages; this alternative would address the wrong dependency.

ASM initially uses a shared RP tree and may switch to source-specific shortest-path forwarding according to design and platform behavior. “Evaluate supported SPT threshold and source-tree design for bandwidth and latency goals without creating RPF inconsistencies” would remedy that alternative situation, but it would not correct the present issue: PIM DR election provides a defined designated router role on a multiaccess segment to avoid conflicting join responsibilities.

“Design SSM-compatible group range, sender addressing and receiver IGMPv3 support end to end” is the supported response when source-specific multicast applications need supported source-aware receiver membership signaling, commonly IGMPv3 for IPv4. Here the decisive response is “Design suitable PIM interface priorities and neighbor reachability for predictable designated-router selection”, so that different intervention does not meet the stated requirement.

Independent rendezvous points do not automatically exchange all active-source information across ASM multicast domains. “Use supported MSDP or a suitable alternative interdomain multicast design with appropriate RP and source policies” applies to that other condition. The reported evidence is a shared LAN has two PIM routers and a new receiver joins, but both routers attempt to act as the first-hop join forwarder for the segment; this alternative would address the wrong dependency.

Without explicit multicast boundary control, group advertisements or forwarding may extend beyond authorized trust domains. “Apply supported multicast group or source boundary filtering at the appropriate WAN and tenant interfaces” would remedy that alternative situation, but it would not correct the present issue: multicast RPF decisions can be sensitive to unicast path selection, including ECMP and asymmetric routing behavior.

“Assess multicast replication at branching points or other supported content distribution design with receiver policy” is the supported response when naive replicated unicast can consume far more shared-link capacity than a suitable multicast tree for many receivers. Here the decisive response is “Align multicast source reachability and acceptable RPF design with supported ECMP handling and stable upstream selection”, so that different intervention does not meet the stated requirement.

RP location affects shared-tree path efficiency and control resilience for ASM groups and can create a remote common-mode dependency. “Choose strategically located and redundant RPs considering source and receiver topology, routing cost and failover” applies to that other condition. The reported evidence is an enterprise adds an equal-cost WAN path and multicast traffic begins failing because the selected upstream RPF path differs from the ingress interface chosen by a source; this alternative would address the wrong dependency.

OSPF hierarchical inter-area connectivity depends on a stable backbone design and resilient area border connectivity. “Design redundant ABRs with valid backbone area connectivity and deterministic cost preferences for inter-area paths” would remedy that alternative situation, but it would not correct the present issue: external Type 2 cost behavior does not account for internal cost in the same way as Type 1 when external metrics differ.

“Design a supported NSSA with correct Type 7 origination and ABR translation handling where needed” is the supported response when a totally stubby or regular stub area cannot originate external LSAs through an internal ASBR in the required manner. Here the decisive response is “Select E1 or E2 route treatment to reflect the required exit preference, testing both external and internal metrics”, so that different intervention does not meet the stated requirement.

A normal area floods external routing information that stub-capable branches may not need when a default route is sufficient. “Choose a supported stub-area design consistently across the area and ensure the ABR provides an appropriate default route” applies to that other condition. The reported evidence is a redistribution design sends external OSPF Type 2 routes across sites with very different internal transit costs, yet expects remote sites to prefer the closest exit; this alternative would address the wrong dependency.

Policing enforces a rate by dropping or remarking excess packets, whereas shaping ordinarily smooths outbound bursts using buffers. “Use shaping for traffic that can tolerate buffering and selective policing where a hard ingress contract is needed” would remedy that alternative situation, but it would not correct the present issue: a high-speed physical port does not imply equal committed service rate, so uncontrolled bursts can be discarded in the provider network.

“Reserve low-latency priority treatment for justified real-time traffic with controlled bandwidth and balanced class allocations” is the supported response when an oversized or unbounded strict-priority queue can consume interface capacity and deny adequate service to other classes. Here the decisive response is “Shape outbound traffic to a suitable rate below the provider policer and apply useful internal priority queues”, so that different intervention does not meet the stated requirement.

Trusting unvalidated endpoint DSCP markings allows unauthorized traffic to consume preferential network resources. “Define an appropriate trust boundary and classify or remark traffic at access based on authenticated application and endpoint context” applies to that other condition. The reported evidence is a branch sends 1 Gbps bursts into an Ethernet handoff while its provider contract allows only 100 Mbps and drops excess traffic unpredictably; this alternative would address the wrong dependency.

Multicast RPF decisions can be sensitive to unicast path selection, including ECMP and asymmetric routing behavior. “Verify source-tree RPF after routing metric changes rather than only testing unicast ping” would remedy that alternative situation, but it would not correct the present issue: naive replicated unicast can consume far more shared-link capacity than a suitable multicast tree for many receivers.

“Audit group range ownership and multicast boundary filters whenever a new partner network connects” is the supported response when without explicit multicast boundary control, group advertisements or forwarding may extend beyond authorized trust domains. Here the decisive response is “Benchmark group sizes and failure behavior before replacing unicast with multicast distribution”, so that different intervention does not meet the stated requirement.

RP location affects shared-tree path efficiency and control resilience for ASM groups and can create a remote common-mode dependency. “Reevaluate RP placement whenever adding large receiver clusters or relocating content sources” applies to that other condition. The reported evidence is a regional network distributes one 20 Mbps live event to sixty branches by sending sixty independent copies across the same core link; this alternative would address the wrong dependency.

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” would remedy that alternative situation, but it would not correct the present issue: OSPF hierarchical inter-area connectivity depends on a stable backbone design and resilient area border connectivity.

“Verify NSSA translation and ABR failover when adding local redistribution at a stub-like branch” is the supported response when a totally stubby or regular stub area cannot originate external LSAs through an internal ASBR in the required manner. Here the decisive response is “Evaluate area zero failure domains and ABR diversity before placing mission-critical applications in branch areas”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is an enterprise creates several OSPF nonbackbone areas linked through a single fragile ABR with no alternate route into area zero; this alternative would address the wrong dependency.

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” 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.

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 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.

Independent rendezvous points do not automatically exchange all active-source information across ASM multicast domains. “Maintain explicit source and RP boundary policy in interdomain multicast peering arrangements” would remedy that alternative situation, but it would not correct the present issue: without explicit multicast boundary control, group advertisements or forwarding may extend beyond authorized trust domains.

“Verify source-tree RPF after routing metric changes rather than only testing unicast ping” is the supported response when multicast RPF decisions can be sensitive to unicast path selection, including ECMP and asymmetric routing behavior. Here the decisive response is “Audit group range ownership and multicast boundary filters whenever a new partner network connects”, so that different intervention does not meet the stated requirement.

Naive replicated unicast can consume far more shared-link capacity than a suitable multicast tree for many receivers. “Benchmark group sizes and failure behavior before replacing unicast with multicast distribution” applies to that other condition. The reported evidence is a company distributes executive multicast video to finance buildings, but the design allows the group to cross into an outsourced guest network; this alternative would address the wrong dependency.

Private transport does not automatically enforce tenant segmentation or prevent unintended route exchange into cloud environments. “Integrate MPLS L3VPN with approved cloud private routing and select per-tenant VRF and gateway route policies” would remedy that alternative situation, but it would not correct the present issue: GNMI is a model-driven management interface commonly using gRPC streaming and structured path/value messages rather than a generic webpage.

“Design supported cloud on-ramp or cloud gateway integration with controlled routing, identity and service security policy” is the supported response when traditional centralized route topology can add delay and consume backbone capacity even when local cloud on-ramp options are available. Here the decisive response is “Implement a supported gNMI client with secure gRPC connectivity and a valid Subscribe request for modeled paths”, so that different intervention does not meet the stated requirement.

TLS mutual authentication depends on valid identity and trust configuration, independent of basic network reachability. “Deploy approved certificates and trust anchors for the telemetry endpoint and collector, including correct service identity names” applies to that other condition. The reported evidence is a collector opens an HTTP webpage and expects to receive streaming gNMI telemetry messages as ordinary JSON page content; this alternative would address the wrong dependency.