Cisco 300-420 Bundle

An IPv4-only underlay cannot natively carry IPv6 forwarding without an overlay or other transition capability. “Use a supported IPv6-over-IPv4 tunnel with correct endpoint reachability, encapsulation security and effective MTU” would remedy that alternative situation, but it would not correct the present issue: BGP aggregation can hide component failures and attract traffic for unreachable portions of the summarized prefix.

“Evaluate path attributes and supported multipath settings, then choose a design that preserves deterministic failover” is the supported response when BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic. Here the decisive response is “Choose an aggregate policy with reviewed component-route dependencies, conservative discard behavior and correct reachability design”, 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. “Enable and verify supported graceful restart with sensible stale timers and failover safeguards where appropriate” applies to that other condition. The reported evidence is a border advertises a BGP aggregate for several site prefixes but after one internal site is withdrawn, the advertised summary still attracts traffic to its unavailable block; this alternative would address the wrong dependency.

MST region membership requires consistent region identifier, revision and VLAN mapping rather than matching only some VLAN names. “Align approved MST region configuration and verify boundary ports and per-instance root placement” would remedy that alternative situation, but it would not correct the present issue: extended nodes and ordinary fabric nodes have distinct supported roles and scale limits; uplink connection alone does not confer every fabric service.

“Design the supported fabric wireless control-plane and data-plane integration with validated WLAN-to-VN mapping” is the supported response when fabric wireless requires supported controller and edge integration and consistent segmentation assignments for mobile clients. Here the decisive response is “Use supported extended-node topology with appropriate fabric-edge parent capacity and port-assignment design”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is a campus wants to hang many simple access switches from an SD-Access fabric edge and assumes each automatically has full fabric border and control-plane functionality; this alternative would address the wrong dependency.

Mobile backup is useful only if real coverage, policy, cost and failure independence support required branch services. “Verify seasonal radio performance and data-cap alarms before relying on cellular as a branch recovery path” would remedy that alternative situation, but it would not correct the present issue: ordinary port-level upgrades may not meet aggregate fiber-capacity and distance requirements when the optical transport must host many independent wavelengths.

“Document E-Line versus E-LAN service boundaries and operational responsibility with the provider” is the supported response when multipoint Ethernet services and many independent E-Line circuits have different Layer 2 forwarding and spanning-tree implications. Here the decisive response is “Use optical engineering validation rather than treating wavelength transport as simple Ethernet aggregation”, so that different intervention does not meet the stated requirement.

A shared provider routing domain cannot preserve independent overlapping tenant address spaces and route targets without isolation. “Audit route targets, route distinguishers and provider CE handoff details during onboarding and acquisitions” applies to that other condition. The reported evidence is two data centers need many high-throughput channels over existing dark fiber but an architect proposes a single low-rate Ethernet handoff for each future application; this alternative would address the wrong dependency.

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” would remedy that alternative situation, but it would not correct the present issue: per-flow IntServ state scales differently from aggregated DiffServ classes and can become operationally expensive for large multi-site deployments.

“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 “Choose a scalable DiffServ class-based policy where application requirements permit, reserving per-flow mechanisms for justified domains”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence 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 alternative would address the wrong dependency.

That change concerns cisco sd wan controller certificate trust, where Secure SD-WAN fabric admission requires authorized organization identifiers and valid identity trust, not just IP routing. The reported issue instead stems from: Tenant route separation blocks cross-VPN reachability until carefully controlled route-target import/export rules make the intended service available.

That change concerns ipsec traffic selector scope, where VPN session status can be healthy while mismatched crypto ACLs or traffic selectors omit the application flow. In this question the necessary remedy is “Design an approved extranet or shared-services VPN import/export model with explicit prefix filters and security enforcement”, which this alternative does not provide.

That change concerns get vpn any to any encryption, where Traditional point-to-point encryption tunnel meshes may add unnecessary topology and scale complexity for a trusted private routed underlay. The observed condition is two enterprise departments use separate MPLS VPNs but need access to one shared CRM subnet without importing all routes from one another; this mechanism addresses another problem.

Local interface carrier may remain up when upstream service fails, so a static route without health tracking can blackhole traffic. “Test off-site failure scenarios where the local modem stays up rather than only unplugging the branch cable” would remedy that alternative situation, but it would not correct the present issue: service encapsulation consumes transport overhead and can exceed an underlay MTU that was sized only for native Ethernet payloads.

“Review VPN shortcut and route optimization features whenever security architecture mandates central inspection” is the supported response when shortcut VPN topology changes can bypass required inspection if the WAN policy assumes every flow transits a central hub. Here the decisive response is “Include provider label and VLAN overhead in handoff acceptance tests and service contracts”, so that different intervention does not meet the stated requirement.

Multiple logical VLANs on the same physical CE and provider device do not provide independent failure domains. “Track physical and provider diversity from rack power to metro access rather than counting only service circuit IDs” applies to that other condition. The reported evidence is a provider delivers a Layer 2 VPN between sites with 1500-byte host payloads, but an extra service label and VLAN tag causes dropped frames in one segment; this alternative would address the wrong dependency.

Remote-only controller dependencies and insufficient regional capacity can degrade onboarding, resiliency and convergence at scale. “Capacity-test controller sessions and regional redundancy before large multi-region migration waves” would remedy that alternative situation, but it would not correct the present issue: static transport preference does not substitute for application-aware path decisions using measured latency, loss and jitter.

“Treat breakout decisions as combined WAN and security design approvals rather than routing-only changes” 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 “Review application SLAs and measurement probes after changing WAN providers or regional geography”, 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. “Test multicast behavior and failure recovery with representative audience sizes before production events” applies to that other condition. The reported evidence is a voice collaboration app takes the least-cost broadband transport even when packet loss breaches an SLA because policy only prefers link color and ignores live performance; this alternative would address the wrong dependency.

Overlay headers reduce usable path MTU and blocked ICMPv6 Packet Too Big feedback can prevent Path MTU Discovery. “Include tunnel and encryption overhead in WAN design capacity and test plans” 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.

“Include IPv6 policy and telemetry reviews in every dual-stack readiness audit” is the supported response when IPv4-only security rules do not automatically enforce the same trust boundary for IPv6 traffic on a dual-stack path. Here the decisive response is “Document address-translation limitations for literal IPv4 references and validate DNS64 behavior during migrations”, 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. “Record transition architecture decision criteria instead of applying one translation model to every workload” 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.

That change concerns qos classification encrypted traffic, where Encryption hides much application payload from intermediate classifiers, so deep packet inspection may not see per-app content inside the tunnel. The reported issue instead stems from: Priority queuing alone cannot create bandwidth beyond circuit capacity, and too many concurrent sessions can oversubscribe voice allocation.

That change concerns class based weighted fair queuing, where Without class-based queue service, different traffic priorities may compete equally under congestion rather than receiving guaranteed minimum allocations. In this question the necessary remedy is “Design call admission or session limits based on codec overhead and failover bandwidth, with controlled class policies”, which this alternative does not provide.

That change concerns qos remarking across carrier boundary, where DSCP semantics and provider class-of-service mappings are not necessarily preserved across an independent administrative domain. The observed condition is a small branch has a 3 Mbps WAN with no admission control and permits twenty simultaneous high-bitrate voice sessions, causing severe jitter; this mechanism addresses another problem.

Local interface carrier may remain up when upstream service fails, so a static route without health tracking can blackhole traffic. “Use supported service probing and tracked next-hop or routing convergence to withdraw an unusable primary path” would remedy that alternative situation, but it would not correct the present issue: shortcut VPN topology changes can bypass required inspection if the WAN policy assumes every flow transits a central hub.

“Negotiate and implement supported provider service MTU and customer handoff frame sizes including encapsulation requirements” is the supported response when service encapsulation consumes transport overhead and can exceed an underlay MTU that was sized only for native Ethernet payloads. Here the decisive response is “Use a security-enforcing hub design or distributed inspection architecture with explicit policy for branch-to-branch traffic”, so that different intervention does not meet the stated requirement.

Multiple logical VLANs on the same physical CE and provider device do not provide independent failure domains. “Design separate CE devices, access paths and service-provider terminations in accordance with the required availability objective” applies to that other condition. The reported evidence is a company permits interbranch traffic only after central security inspection, but a newly deployed direct branch tunnel bypasses the hub firewall; this alternative would address the wrong dependency.

Conventional iBGP full mesh grows quadratically and becomes costly to configure, observe and recover. “Introduce redundant route reflectors with appropriate client hierarchy and loop-prevention identifiers” would remedy that alternative situation, but it would not correct the present issue: AS-path prepending mainly affects remote path selection; outbound path preference within the local AS is commonly controlled with local preference.

“Use supported BGP MED where appropriate, coordinate the provider's comparison behavior and keep resilient alternate exits” is the supported response when internal OSPF cost does not communicate an intended interconnect preference to the neighboring autonomous system. Here the decisive response is “Set governed BGP local preference on inbound routes from the preferred provider, with consistent internal propagation”, 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 dual-homed enterprise wants all internal sites to prefer the primary provider for outbound traffic but adjusts AS-path prepending on inbound advertisements instead; this alternative would address the wrong dependency.