Cisco 300-420 Bundle

FHRP presence alone may not account for upstream path viability without appropriate object or interface tracking. “Track the required upstream path and decrement priority enough for a healthy standby gateway to assume forwarding” would remedy that alternative situation, but it would not correct the present issue: without deliberate STP root design, Layer 2 forwarding paths may traverse inappropriate access hardware.

“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 “Set primary and backup STP roots on appropriate distribution devices and validate bridge priority and path costs”, 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 has redundant access trunks but an unmanaged access switch wins spanning-tree root after it comes online with an unexpectedly favorable bridge priority; this alternative would address the wrong dependency.

A flat random allocation from the /48 wastes the opportunity for site-level hierarchy and complicates growth and route summarization. “Reserve logical per-site prefixes within the /48, allocate appropriate /64 LANs and maintain documented room for subnets and future services” would remedy that alternative situation, but it would not correct the present issue: IPv6-only clients cannot communicate with IPv4-only services without supported translation and suitable destination synthesis.

“Budget tunnel overhead in MTU planning, preserve required ICMPv6 control messages and validate endpoints' segment sizes” is the supported response when overlay headers reduce usable path MTU and blocked ICMPv6 Packet Too Big feedback can prevent Path MTU Discovery. Here the decisive response is “Design appropriate NAT64 plus DNS64 service boundaries, DNS behavior and application compatibility exceptions”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence 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 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: DSCP semantics and provider class-of-service mappings are not necessarily preserved across an independent administrative domain.

“Implement appropriate CBWFQ or platform-supported scheduler weights after classifying actual traffic” is the supported response when without class-based queue service, different traffic priorities may compete equally under congestion rather than receiving guaranteed minimum allocations. Here the decisive response is “Negotiate and implement DSCP-to-provider-CoS mapping and verify marking at each trust boundary”, so that different intervention does not meet the stated requirement.

Priority queuing alone cannot create bandwidth beyond circuit capacity, and too many concurrent sessions can oversubscribe voice allocation. “Design call admission or session limits based on codec overhead and failover bandwidth, with controlled class policies” applies to that other condition. The reported evidence is a branch marks a critical application with DSCP 46, but the MPLS provider maps it into ordinary treatment because service-class translation was never agreed; this alternative would address the wrong dependency.

A conventional port channel cannot span unrelated independent switches without a supported multichassis or stacking mechanism. “Prove peer-link, keepalive and split-brain failure behavior before choosing dual-chassis aggregation” would remedy that alternative situation, but it would not correct the present issue: etherChannel members need compatible Layer 2 settings and negotiated bundling state to represent a correct logical link.

“Track real endpoint power profiles and spare capacity during access switch procurement” is the supported response when available PoE power budget and per-port capabilities determine whether simultaneous endpoint power requirements can be met. Here the decisive response is “Audit allowed VLANs and link settings at both ends when adding or replacing bundle members”, so that different intervention does not meet the stated requirement.

Ordinary directed and local broadcasts do not automatically cross routed boundaries, so an explicit authorized delivery design is required. “Document WoL security and relay dependencies when redesigning campus routing and NAC controls” applies to that other condition. The reported evidence is an access switch bundles two ports toward a distribution switch but one member carries different VLAN tags and the bundle intermittently drops traffic; this alternative would address the wrong dependency.

Mixed or unsuitable metric styles can undermine consistent path-cost planning and overflow the intended metric range. “Govern IS-IS metric templates and perform cost-map reviews when adding high-capacity links or changing topology” would remedy that alternative situation, but it would not correct the present issue: an unprotected adjacency trust boundary can admit unauthorized IS-IS control messages into a routing domain.

“Compare aggregate reachability against live component prefixes during area topology changes” is the supported response when summary advertisement can attract destinations no longer reachable through the summarizing area, creating a predictable blackhole. Here the decisive response is “Rotate routing authentication keys with overlap windows and verify peer inventory during link provisioning”, so that different intervention does not meet the stated requirement.

Protocol adjacency and IPv4 routes do not alone establish correct IPv6 reachability, interface addressing or address-family support. “Test IPv4 and IPv6 reachability separately when extending a stable routing protocol deployment” applies to that other condition. The reported evidence is routing peers on a shared provider Ethernet segment accept IS-IS adjacencies without authentication, allowing an unintended device to affect topology calculations; this alternative would address the wrong dependency.

An oversized or unbounded strict-priority queue can consume interface capacity and deny adequate service to other classes. “Reserve low-latency priority treatment for justified real-time traffic with controlled bandwidth and balanced class allocations” would remedy that alternative situation, but it would not correct the present issue: policing enforces a rate by dropping or remarking excess packets, whereas shaping ordinarily smooths outbound bursts using buffers.

“Choose a scalable DiffServ class-based policy where application requirements permit, reserving per-flow mechanisms for justified domains” is the supported response when per-flow IntServ state scales differently from aggregated DiffServ classes and can become operationally expensive for large multi-site deployments. Here the decisive response is “Use shaping for traffic that can tolerate buffering and selective policing where a hard ingress contract is needed”, so that different intervention does not meet the stated requirement.

A high-speed physical port does not imply equal committed service rate, so uncontrolled bursts can be discarded in the provider network. “Shape outbound traffic to a suitable rate below the provider policer and apply useful internal priority queues” applies to that other condition. The reported evidence is a design uses aggressive ingress policing for interactive video and expects the policer to buffer all bursts until bandwidth becomes available; 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: provider-dependent global prefixes may require renumbering when upstream connectivity changes and do not replace a stable local-only design.

“Validate IPv6 prefix lengths against actual endpoint SLAAC and Neighbor Discovery requirements before deployment” 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 “Document ULA-to-global boundaries and ensure policies and DNS do not accidentally expose internal-only IPv6 addresses”, so that different intervention does not meet the stated requirement.

Premature use of a partially ready intermediate system can blackhole transit despite apparently formed control-plane neighbors. “Include restart and overload-bit behavior in IS-IS maintenance acceptance and failover testing” 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.

That change concerns pim sparse mode receiver path joins, where PIM sparse mode forwarding relies on supported multicast routing and receiver membership along the required multicast distribution tree. The reported issue instead stems from: Per-flow IntServ state scales differently from aggregated DiffServ classes and can become operationally expensive for large multi-site deployments.

That change concerns qos shaping on provider lower rate link, where A high-speed physical port does not imply equal committed service rate, so uncontrolled bursts can be discarded in the provider network. In this question the necessary remedy is “Choose a scalable DiffServ class-based policy where application requirements permit, reserving per-flow mechanisms for justified domains”, which this alternative does not provide.

That change concerns voice priority queuing starvation, where An oversized or unbounded strict-priority queue can consume interface capacity and deny adequate service to other classes. The observed condition is a campus WAN operator proposes maintaining individual RSVP reservations for every video stream across thousands of remote endpoints despite modest router control capacity; this mechanism addresses another problem.

That change concerns netconf transaction candidate datastore, where NETCONF can expose candidate datastores, locking and commit operations where supported, unlike assuming every management interface has equivalent transactions. The reported issue instead stems from: Vendor-native data models may expose platform-specific schema that cannot be queried identically across different vendors.

That change concerns cisco native YANG proprietary feature coverage, where Standardized models do not necessarily represent every vendor-specific operational or configuration feature. In this question the necessary remedy is “Prefer a suitable standards-based IETF model for portable interface telemetry, documenting implementation gaps and vendor extensions”, which this alternative does not provide.

That change concerns openconfig cross-platform telemetry models, where OpenConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform. The observed condition 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 mechanism addresses another problem.

NETCONF and RESTCONF share model-driven concepts but use different protocol transports, operation semantics and session behavior. “Match API protocol to the orchestrator requirements and supported device capabilities, including SSH/XML NETCONF or HTTP/RESTCONF workflows” would remedy that alternative situation, but it would not correct the present issue: machine-readable data model revisions and capabilities can differ across platform versions even if management connectivity remains healthy.

“Use the supported Cisco native YANG model for the particular feature with platform and software-version capability checks” is the supported response when standardized models do not necessarily represent every vendor-specific operational or configuration feature. Here the decisive response is “Read supported YANG module revisions and capabilities and implement controlled schema compatibility or versioned adapters”, so that different intervention does not meet the stated requirement.

OpenConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform. “Select supported OpenConfig telemetry modules, verify revisions and normalize exceptions without assuming universal coverage” applies to that other condition. The reported evidence is a network automation release breaks when some routers are upgraded to a newer software image that exposes changed model revisions and namespaces; 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: multipoint Ethernet services and many independent E-Line circuits have different Layer 2 forwarding and spanning-tree implications.

“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 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.