Cisco 300-420 Bundle

Ordinary underlay reachability does not assign endpoint onboarding and VXLAN edge functions to a nonfabric access device. “Provision eligible access devices as supported fabric edge nodes and verify host onboarding and virtual network assignments” would remedy that alternative situation, but it would not correct the present issue: fabric overlay encapsulation adds overhead beyond ordinary IP reachability and depends on a healthy L3 underlay.

“Select appropriate fabric border nodes and external routing policy matching the site's transit and segmentation needs” is the supported response when fabric overlay endpoints require a suitable border function to exchange external route reachability with nonfabric networks. Here the decisive response is “Provide resilient IP underlay reachability and adequate end-to-end MTU for supported fabric encapsulation”, so that different intervention does not meet the stated requirement.

A fabric control plane supplies locator information, while the data plane uses supported VXLAN encapsulation to carry endpoint traffic. “Design overlay forwarding paths with validated VXLAN reachability, fabric edge encapsulation and proper transport MTU” applies to that other condition. The reported evidence is a new SD-Access fabric edge can reach control nodes by IP but VXLAN user traffic fails because the routed underlay path has insufficient MTU; this alternative would address the wrong dependency.

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: physical link-up is insufficient to guarantee bidirectional signal integrity, which can affect control-plane protocols and forwarding.

“Enable Root Guard on appropriate downstream designated ports and keep intended root roles explicit” is the supported response when superior BPDUs on an untrusted downstream link can alter STP root selection unless the boundary is protected. Here the decisive response is “Enable appropriate UDLD modes on supported fiber links and validate shutdown and recovery procedures”, so that different intervention does not meet the stated requirement.

A per-VLAN spanning-tree model scales protocol state with VLAN count and may become less efficient than suitable aggregated instances. “Assess MST or Layer 3 access boundaries against actual traffic steering and availability requirements” applies to that other condition. The reported evidence is a duplex fiber campus uplink works in one direction but not the other, and interface carrier stays partially healthy while protocols behave unpredictably; 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: a syntactically installed QoS policy does not establish that actual applications match intended classes or receive required forwarding treatment.

“Reserve suitable queue and burst tolerance based on codec behavior, media priority and empirically observed peak load” is the supported response when average throughput can hide instantaneous bursts and delay variation that disrupt real-time media even when link utilization seems moderate. Here the decisive response is “Run controlled traffic tests and inspect class and queue counters, delay and drop statistics end to end”, so that different intervention does not meet the stated requirement.

Input classification and policing operate on traffic entering an interface, while output scheduling applies to egress congestion. “Place supported ingress policing and remarking at appropriate boundaries and egress queuing at the actual bottleneck” applies to that other condition. The reported evidence is an enterprise labels its QoS design complete because configuration commands were accepted but never checks packet classifications or queue drops; this alternative would address the wrong dependency.

Stateful inspection needs coherent bidirectional flow visibility, while independent routing cost choices can create asymmetric paths. “Include reverse-path verification in campus security zone design and ECMP changes” 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.

“Establish timer and session-count budgets per platform before promising uniform subsecond convergence” is the supported response when high session counts and excessively aggressive timers can exhaust control resources and cause false routing flaps. Here the decisive response is “Test flow hashing and single-link failure behavior rather than assuming equal packet splitting from two cables”, 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. “Audit shared services route leaks and ACLs together after each tenant or service onboarding” 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.

A /15 covers two consecutive aligned /16 networks and the selected /15 omits 10.66.0.0/16 while including unintended space. “Create aligned aggregates that cover actual component prefixes and validate binary prefix boundaries and the destination routing behavior” would remedy that alternative situation, but it would not correct the present issue: a flat random allocation from the /48 wastes the opportunity for site-level hierarchy and complicates growth and route summarization.

“Reserve contiguous region-sized address blocks, allocate branch VLSM prefixes inside each block and summarize only reachable ranges at distribution boundaries” is the supported response when randomly scattered branch subnets prevent region-level summarization and make routing and change control unnecessarily complex. Here the decisive response is “Reserve logical per-site prefixes within the /48, allocate appropriate /64 LANs and maintain documented room for subnets and future services”, so that different intervention does not meet the stated requirement.

An IPv4 /27 ordinarily has only thirty usable host addresses, so it cannot accommodate the stated phones and gateway. “Allocate a suitably sized /25 or larger subnet after accounting for network, broadcast, gateway and expected device growth” applies to that other condition. The reported evidence is an organization receives an IPv6 /48 and assigns different arbitrary /64s to access LANs without reserving site blocks or a summarization scheme; this alternative would address the wrong dependency.

Tenant route separation blocks cross-VPN reachability until carefully controlled route-target import/export rules make the intended service available. “Design an approved extranet or shared-services VPN import/export model with explicit prefix filters and security enforcement” would remedy that alternative situation, but it would not correct the present issue: GRE provides encapsulation for multiple protocols but does not itself encrypt or authenticate payload confidentiality.

“Compare direct cloud private interconnect with managed Internet VPN based on security, bandwidth, route exchange and service commitments” is the supported response when an encrypted Internet overlay does not provide the same private carrier connectivity, SLA and traffic-engineering options as a qualified dedicated cloud circuit. Here the decisive response is “Combine supported GRE transport with an appropriate IPsec protection design, or select a secure alternative meeting multicast needs”, so that different intervention does not meet the stated requirement.

A purely hub-and-spoke forwarding policy can add latency and load when the DMVPN design is intended to allow direct spoke shortcuts. “Use a supported DMVPN phase and NHRP routing design that safely establishes eligible spoke-to-spoke tunnels” applies to that other condition. The reported evidence is an architect proposes plain GRE between remote branches to carry multicast routing updates and claims GRE alone satisfies corporate confidentiality requirements; this alternative would address the wrong dependency.

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” 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.

“Design redundant ABRs with valid backbone area connectivity and deterministic cost preferences for inter-area paths” is the supported response when OSPF hierarchical inter-area connectivity depends on a stable backbone design and resilient area border connectivity. Here the decisive response is “Design a supported NSSA with correct Type 7 origination and ABR translation handling where needed”, 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. “Allocate summarizable ranges and apply appropriate ABR area range configuration with complete component-route validation” 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.

Input classification and policing operate on traffic entering an interface, while output scheduling applies to egress congestion. “Require interface-direction diagrams when reviewing QoS policies” would remedy that alternative situation, but it would not correct the present issue: average throughput can hide instantaneous bursts and delay variation that disrupt real-time media even when link utilization seems moderate.

“Capture before/after QoS telemetry and review counters after software and provider changes” is the supported response when a syntactically installed QoS policy does not establish that actual applications match intended classes or receive required forwarding treatment. Here the decisive response is “Measure peak burst distributions and media quality rather than only daily average link utilization”, so that different intervention does not meet the stated requirement.

Policy percentages alone do not preserve service if critical aggregate traffic exceeds reduced failover link capacity. “Maintain separate primary and failover traffic budgets and test both periodically” applies to that other condition. The reported evidence is interactive training video experiences brief rate bursts, and engineers allocate only average bitrate with no jitter or loss allowance across the WAN; this alternative would address the wrong dependency.

Central monitoring infrastructure can become a single point of failure even when individual access devices have redundant uplinks. “Design appropriate collector and transport redundancy with supported failover and secure retention behavior” would remedy that alternative situation, but it would not correct the present issue: multicast RPF typically checks the route back toward the source or RP, not merely whether a receiver destination is reachable.

“Design supported redundant RP mechanisms with consistent group mappings and reachability across the multicast domain” is the supported response when ASM shared-tree setup may depend on reachable RP control functions that need deliberate redundancy. Here the decisive response is “Design correct multicast reverse paths and compatible unicast routing so upstream interfaces pass the RPF check”, so that different intervention does not meet the stated requirement.

Uncoordinated system clocks undermine log chronology, audit correlation and incident reconstruction. “Use resilient approved NTP sources with authenticated or trusted network delivery where supported” applies to that other condition. The reported evidence is a multicast receiver sees no video even though the router has a unicast route to the receiver, and engineers inspect only destination forwarding; this alternative would address the wrong dependency.

Repeated broad request-response polling can impose higher overhead than selective model-driven subscription updates for suitable telemetry. “Use platform-supported model-driven telemetry subscriptions for required state paths with sensible reporting intervals and collector capacity” would remedy that alternative situation, but it would not correct the present issue: coarse periodic publication can delay visibility of short state transitions and is not equivalent to supported event-driven on-change reporting.

“Match API protocol to the orchestrator requirements and supported device capabilities, including SSH/XML NETCONF or HTTP/RESTCONF workflows” is the supported response when NETCONF and RESTCONF share model-driven concepts but use different protocol transports, operation semantics and session behavior. Here the decisive response is “Use supported on-change telemetry for the neighbor state path with safeguards for subscriber load and update volume”, so that different intervention does not meet the stated requirement.

On-change subscriptions report eligible state changes, not necessarily uniformly spaced observations required for some time-series analytics. “Choose supported periodic or sample telemetry publication with a suitable interval for the planning metric” applies to that other condition. The reported evidence is a network team wants immediate notification when a BGP neighbor state changes but configures a ten-minute periodic sample on the relevant state model; this alternative would address the wrong dependency.

Graceful restart depends on both peers' supported capabilities and bounded stale-route handling, not merely a routing session name. “Enable and verify supported graceful restart with sensible stale timers and failover safeguards where appropriate” would remedy that alternative situation, but it would not correct the present issue: provider-dependent global prefixes may require renumbering when upstream connectivity changes and do not replace a stable local-only design.

“Allocate /64 prefixes for SLAAC access segments while using more specialized lengths only in supported and justified designs” is the supported response when typical Ethernet SLAAC uses /64 interface identifiers and ordinary host autoconfiguration expectations are not met by arbitrary longer access prefixes. Here the decisive response is “Use an appropriately generated unique-local IPv6 prefix for suitable internal services alongside routed global addressing where Internet access is needed”, so that different intervention does not meet the stated requirement.

Network dual stacking alone does not add AAAA DNS records, IPv6 listening services, security policy or path validation to existing applications. “Plan application-by-application dual-stack readiness including DNS, access controls, routing, management and rollback verification” applies to that other condition. The reported evidence is a campus requires internal IPv6 communication that survives ISP changes but uses only a provider-assigned global prefix for every local infrastructure service; this alternative would address the wrong dependency.