Cisco 300-420 Bundle

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: multipoint Ethernet services and many independent E-Line circuits have different Layer 2 forwarding and spanning-tree implications.

“Choose an eligible provider Layer 2 VPN or Ethernet private line design if extending a broadcast domain is genuinely required” is the supported response when an MPLS Layer 3 VPN routes IP among separated CE networks rather than delivering a transparent Layer 2 Ethernet service. Here the decisive response is “Choose appropriate Metro Ethernet point-to-point or multipoint service topology with explicit VLAN and loop-avoidance design”, 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 manufacturing campus buys point-to-point Ethernet links for twenty buildings but plans to treat the collection as a single broadcast mesh without loop controls; 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: an IPv4-only underlay cannot natively carry IPv6 forwarding without an overlay or other transition capability.

“Choose an aggregate policy with reviewed component-route dependencies, conservative discard behavior and correct reachability design” is the supported response when BGP aggregation can hide component failures and attract traffic for unreachable portions of the summarized prefix. Here the decisive response is “Use a supported IPv6-over-IPv4 tunnel with correct endpoint reachability, encapsulation security and effective MTU”, so that different intervention does not meet the stated requirement.

BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic. “Evaluate path attributes and supported multipath settings, then choose a design that preserves deterministic failover” applies to that other condition. The reported evidence is a branch runs IPv6-only management endpoints over a provider transport that supports IPv4 underlay only, but the design expects native IPv6 routing to work end to end; this alternative would address the wrong dependency.

An unprotected adjacency trust boundary can admit unauthorized IS-IS control messages into a routing domain. “Rotate routing authentication keys with overlap windows and verify peer inventory during link provisioning” would remedy that alternative situation, but it would not correct the present issue: unbounded EIGRP query scope and nontransit spokes can prolong active route computation across a large topology.

“Govern IS-IS metric templates and perform cost-map reviews when adding high-capacity links or changing topology” is the supported response when mixed or unsuitable metric styles can undermine consistent path-cost planning and overflow the intended metric range. Here the decisive response is “Validate stub declaration and query-domain boundaries for every newly onboarded nontransit branch”, so that different intervention does not meet the stated requirement.

Summary advertisement can attract destinations no longer reachable through the summarizing area, creating a predictable blackhole. “Compare aggregate reachability against live component prefixes during area topology changes” applies to that other condition. The reported evidence is a large hub-and-spoke EIGRP deployment sends queries into hundreds of branch routers during a core route failure, increasing convergence delay; this alternative would address the wrong dependency.

IS-IS Level 1 operates within an area while Level 2 provides inter-area connectivity and should bound unwanted topology flooding. “Design appropriate Level 1 and Level 2 adjacency placement with resilient L1/L2 border routers and reachable inter-area summaries” would remedy that alternative situation, but it would not correct the present issue: summary advertisement can attract destinations no longer reachable through the summarizing area, creating a predictable blackhole.

“Standardize supported wide-metric design and audit interface cost policies across participating IS-IS devices” is the supported response when mixed or unsuitable metric styles can undermine consistent path-cost planning and overflow the intended metric range. Here the decisive response is “Advertise summaries only with valid downstream coverage or an explicitly documented safe discard and failover behavior”, so that different intervention does not meet the stated requirement.

Unbounded EIGRP query scope and nontransit spokes can prolong active route computation across a large topology. “Declare eligible nontransit branches as EIGRP stubs and summarize at appropriate aggregation points with verified alternate paths” applies to that other condition. The reported evidence is a regional IS-IS border advertises a broad summary after several internal prefixes have been withdrawn and remote traffic begins hitting an aggregate discard route; this alternative would address the wrong dependency.

RESTCONF uses resource-oriented HTTP methods with defined read and write semantics, so GET is not an appropriate configuration write operation. “Use supported RESTCONF PATCH, PUT or POST methods at correct YANG resource paths with authorization and content types” would remedy that alternative situation, but it would not correct the present issue: repeated broad request-response polling can impose higher overhead than selective model-driven subscription updates for suitable telemetry.

“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 platform-supported model-driven telemetry subscriptions for required state paths with sensible reporting intervals and collector capacity”, 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 WAN operations team polls thousands of interface counters through legacy SNMP every few seconds and saturates device management CPU during incidents; this alternative would address the wrong dependency.

Extending Layer 2 broadly across campus buildings increases loop, convergence and failure-domain exposure. “Design routed access where supported, using local Layer 3 boundaries and deterministic IGP connectivity between buildings” would remedy that alternative situation, but it would not correct the present issue: routing graceful restart requires compatible neighbor capability and safe stale-route lifetimes, not merely redundant uplinks.

“Select a validated stacking or virtual-switch architecture and plan supervisor, interconnect and software compatibility” is the supported response when a virtualized or stacked switching design needs supported control, state and multichassis link mechanisms to act as one logical system. Here the decisive response is “Use supported graceful restart and nonstop forwarding features only where peer compatibility and forwarding state can be verified”, so that different intervention does not meet the stated requirement.

Unprotected edge-port fast transition can introduce topology-change or loop risks if another bridge is attached. “Apply supported PortFast or edge behavior with BPDU Guard and an approved exception procedure for genuine uplinks” applies to that other condition. The reported evidence 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 alternative would address the wrong dependency.

OpenConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform. “Version model support matrices and review schema revisions before monitoring-platform upgrades” would remedy that alternative situation, but it would not correct the present issue: vendor-native data models may expose platform-specific schema that cannot be queried identically across different vendors.

“Keep proprietary model use isolated and documented so future portability work remains manageable” is the supported response when standardized models do not necessarily represent every vendor-specific operational or configuration feature. Here the decisive response is “Test cross-vendor schema availability before promising identical API behavior for every device”, so that different intervention does not meet the stated requirement.

Machine-readable data model revisions and capabilities can differ across platform versions even if management connectivity remains healthy. “Include API schema contract tests and rollback in every network software upgrade program” applies to that other condition. The reported evidence is a national enterprise must collect interface statistics from routers supplied by three vendors, but a developer builds everything against one Cisco-proprietary YANG path; this alternative would address the wrong dependency.

EIGRP unequal-cost load sharing is not enabled simply because multiple routes exist and is constrained by feasibility and variance. “Assess feasible successors and apply an approved variance design with realistic traffic-share expectations” would remedy that alternative situation, but it would not correct the present issue: local preference is not exported between autonomous systems, so changing it cannot directly govern external networks' inbound selection.

“Introduce redundant route reflectors with appropriate client hierarchy and loop-prevention identifiers” is the supported response when conventional iBGP full mesh grows quadratically and becomes costly to configure, observe and recover. Here the decisive response is “Apply approved outbound AS-path prepending on the less-preferred transit and check provider acceptance and alternate routing”, so that different intervention does not meet the stated requirement.

AS-path prepending mainly affects remote path selection; outbound path preference within the local AS is commonly controlled with local preference. “Set governed BGP local preference on inbound routes from the preferred provider, with consistent internal propagation” applies to that other condition. The reported evidence is a multihomed public service wants remote networks to prefer one upstream for inbound traffic but changes only its own local preference; this alternative would address the wrong dependency.

Superior BPDUs on an untrusted downstream link can alter STP root selection unless the boundary is protected. “Separate trusted infrastructure trunk roles from untrusted tenant-facing links in STP templates” would remedy that alternative situation, but it would not correct the present issue: a per-VLAN spanning-tree model scales protocol state with VLAN count and may become less efficient than suitable aggregated instances.

“Inspect fiber and BPDU loss diagnostics during campus convergence design reviews” is the supported response when a non-designated STP port losing expected control messages can create a loop if it incorrectly assumes the superior path vanished. Here the decisive response is “Include VLAN-count forecasts in campus Layer 2 architecture capacity planning”, so that different intervention does not meet the stated requirement.

Physical link-up is insufficient to guarantee bidirectional signal integrity, which can affect control-plane protocols and forwarding. “Include unidirectional-link testing in fiber plant acceptance and high-availability reviews” applies to that other condition. The reported evidence is a campus uses hundreds of VLANs with distinct rapid spanning-tree instances and experiences growing CPU and change-control complexity; this alternative would address the wrong dependency.

PIM sparse mode forwarding relies on supported multicast routing and receiver membership along the required multicast distribution tree. “Enable appropriate PIM and IGMP behavior on intended routed interfaces and validate RP and RPF reachability” would remedy that alternative situation, but it would not correct the present issue: a dense many-to-many application can impose excessive source tree state if its delivery model ignores suitable shared bidirectional multicast designs.

“Design suitable PIM interface priorities and neighbor reachability for predictable designated-router selection” is the supported response when PIM DR election provides a defined designated router role on a multiaccess segment to avoid conflicting join responsibilities. Here the decisive response is “Evaluate bidirectional PIM or another supported distribution method against source count, RP and security requirements”, so that different intervention does not meet the stated requirement.

Source-specific multicast applications need supported source-aware receiver membership signaling, commonly IGMPv3 for IPv4. “Design SSM-compatible group range, sender addressing and receiver IGMPv3 support end to end” applies to that other condition. The reported evidence is a collaboration application has many multicast senders in the same group and operators propose building separate source-specific trees for every participant; this alternative would address the wrong dependency.

A single endpoint map/control-plane service is a common-mode availability risk even with redundant data-plane links. “Design supported control-plane node redundancy and test endpoint registration continuity during node loss” would remedy that alternative situation, but it would not correct the present issue: link redundancy within the fabric does not guarantee sufficient external border forwarding capacity during degraded operation.

“Design supported fabric-to-fabric transit via qualified borders and consistent virtual-network route and security policy” is the supported response when physical underlay IP connectivity does not by itself establish appropriate inter-fabric transit, route exchange and segmentation policy. Here the decisive response is “Size border nodes and redundant exits for N-minus-one load, applying failure-domain and traffic-engineering requirements”, so that different intervention does not meet the stated requirement.

Extended nodes and ordinary fabric nodes have distinct supported roles and scale limits; uplink connection alone does not confer every fabric service. “Use supported extended-node topology with appropriate fabric-edge parent capacity and port-assignment design” applies to that other condition. The reported evidence is a fabric design has redundant edge uplinks but no redundant border capacity, so a single border failure overloads the remaining exit path; this alternative would address the wrong dependency.