Cisco 300-420 Bundle

Using only the affected data-plane overlay for operational access can eliminate remote troubleshooting when the fabric fails. “Provide an appropriately secured independent management path or out-of-band recovery access for critical WAN edges” would remedy that alternative situation, but it would not correct the present issue: an MPLS Layer 3 VPN routes IP among separated CE networks rather than delivering a transparent Layer 2 Ethernet service.

“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 an eligible provider Layer 2 VPN or Ethernet private line design if extending a broadcast domain is genuinely required”, 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 retailer wants two facilities to operate on one Ethernet broadcast domain across a managed provider network, but its proposed ordinary routed MPLS L3VPN does not transport Ethernet frames; 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. “Review route target overlaps and firewall rules together when allowing cross-VPN shared services” would remedy that alternative situation, but it would not correct the present issue: local interface carrier may remain up when upstream service fails, so a static route without health tracking can blackhole traffic.

“Validate provider policy and route advertisement behavior after every BGP contract change” is the supported response when uncontrolled multihoming can select unpredictable exits and cause asymmetry or suboptimal paths under provider changes. Here the decisive response is “Test off-site failure scenarios where the local modem stays up rather than only unplugging the branch cable”, so that different intervention does not meet the stated requirement.

Shortcut VPN topology changes can bypass required inspection if the WAN policy assumes every flow transits a central hub. “Review VPN shortcut and route optimization features whenever security architecture mandates central inspection” applies to that other condition. The reported evidence is a branch prefers fiber Internet over backup DSL but its static primary default route remains installed after an upstream outage beyond the local Ethernet handoff; 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. “Test multicast forwarding path changes and source-tree utilization for large streaming applications” would remedy that alternative situation, but it would not correct the present issue: trusting unvalidated endpoint DSCP markings allows unauthorized traffic to consume preferential network resources.

“Review queue bandwidth guarantees and peak-rate policing as service demand changes” 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 “Audit QoS trust maps when onboarding new endpoint types or enabling unmanaged switch ports”, so that different intervention does not meet the stated requirement.

Per-flow IntServ state scales differently from aggregated DiffServ classes and can become operationally expensive for large multi-site deployments. “Evaluate per-flow state, class counts and provider behavior before committing to any QoS architecture” applies to that other condition. The reported evidence is a user-controlled workstation marks all outbound bulk backup packets as expedited forwarding, causing voice queues to saturate during office hours; this alternative would address the wrong dependency.

Local breakout bypasses central inspection unless equivalent secure edge controls and policy are deliberately placed. “Treat breakout decisions as combined WAN and security design approvals rather than routing-only changes” would remedy that alternative situation, but it would not correct the present issue: an unsegmented overlay routing context can make trust-boundary errors more likely even if some edge access rules exist.

“Capacity-test controller sessions and regional redundancy before large multi-region migration waves” is the supported response when remote-only controller dependencies and insufficient regional capacity can degrade onboarding, resiliency and convergence at scale. Here the decisive response is “Review VPN to VRF mapping and centralized policy whenever adding new tenant classes”, 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 guest Internet access and regulated internal branch traffic share one SD-WAN service VPN and use ordinary address filters for separation; this alternative would address the wrong dependency.

Without class-based queue service, different traffic priorities may compete equally under congestion rather than receiving guaranteed minimum allocations. “Implement appropriate CBWFQ or platform-supported scheduler weights after classifying actual traffic” would remedy that alternative situation, but it would not correct the present issue: without proper management traffic classification and minimum bandwidth, congestion can starve necessary operations traffic.

“Design redundant remote syslog collectors with protected transport, appropriate facilities and retention controls” is the supported response when local log storage and rollover cannot substitute for reliable centralized timestamped security event retention. Here the decisive response is “Classify authentic management flows and allocate controlled minimum service within the WAN's QoS policy”, so that different intervention does not meet the stated requirement.

In-band-only management can share a fault with the network being repaired, eliminating the ability to recover remotely. “Provide secure out-of-band management through independent transport, power and authentication suitable for critical nodes” applies to that other condition. The reported evidence is a WAN runs at capacity during remote backup jobs and incident responders lose SSH and telemetry access precisely when troubleshooting is needed; this alternative would address the wrong dependency.

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” would remedy that alternative situation, but it would not correct the present issue: the orchestration function helps WAN edges discover and authenticate to the fabric but should not be placed in the regular data forwarding path.

“Choose appropriate low-latency WAN transport and QoS treatment, evaluating cost, resilience and route diversity” is the supported response when bandwidth alone does not determine application suitability when propagation delay and jitter exceed interactive service limits. Here the decisive response is “Design supported Catalyst SD-WAN orchestrator reachability and certificate trust separately from data-plane transport tunnels”, so that different intervention does not meet the stated requirement.

N-minus-one operation cannot carry combined load if each remaining link lacks spare capacity or business traffic prioritization. “Size redundant WAN capacity for failure-state critical loads or design explicit congestion and traffic-class degradation policy” applies to that other condition. The reported evidence is a design document treats Cisco SD-WAN orchestration as the same component that carries every branch's user payload rather than enabling secure device discovery; this alternative would address the wrong dependency.

A hybrid deployment can transfer sensitive data or metadata across administrative and geographic boundaries even when application compute stays on-premises. “Design controlled hybrid data flow, regional placement and access policies that satisfy residency and connectivity requirements” would remedy that alternative situation, but it would not correct the present issue: openConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform.

“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 “Select supported OpenConfig telemetry modules, verify revisions and normalize exceptions without assuming universal coverage”, so that different intervention does not meet the stated requirement.

NETCONF can expose candidate datastores, locking and commit operations where supported, unlike assuming every management interface has equivalent transactions. “Design a supported NETCONF workflow with lock, edit-config, validate, commit and rollback handling for the device capabilities” applies to that other condition. The reported evidence is a monitoring platform wants consistent operational telemetry across diverse vendor routers, but teams conflate OpenConfig definitions with the device's vendor-specific CLI configuration; 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: PIM DR election provides a defined designated router role on a multiaccess segment to avoid conflicting join responsibilities.

“Verify switch snooping and receiver protocol versions before enabling SSM at scale” 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 “Record PIM DR priorities and test host join continuity after an access router outage”, so that different intervention does not meet the stated requirement.

A dense many-to-many application can impose excessive source tree state if its delivery model ignores suitable shared bidirectional multicast designs. “Model source and receiver population, not just one test stream, when selecting multicast mode” 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.

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: protocol adjacency and IPv4 routes do not alone establish correct IPv6 reachability, interface addressing or address-family support.

“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 “Implement supported IS-IS IPv6 reachability with interface family configuration and consistent topology preferences”, 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 network has existing IS-IS IPv4 reachability and adds IPv6-only applications, but the design assumes IPv4 reachability automatically creates IPv6 forwarding information; this alternative would address the wrong dependency.

ASM shared-tree setup may depend on reachable RP control functions that need deliberate redundancy. “Design supported redundant RP mechanisms with consistent group mappings and reachability across the multicast domain” would remedy that alternative situation, but it would not correct the present issue: local log storage and rollover cannot substitute for reliable centralized timestamped security event retention.

“Create a supported management VRF or equivalent separated context and tightly controlled shared services as needed” is the supported response when a common routing table broadens the management attack surface and increases risk of route or ACL leakage. Here the decisive response is “Design redundant remote syslog collectors with protected transport, appropriate facilities and retention controls”, so that different intervention does not meet the stated requirement.

In-band-only management can share a fault with the network being repaired, eliminating the ability to recover remotely. “Provide secure out-of-band management through independent transport, power and authentication suitable for critical nodes” applies to that other condition. The reported evidence is a campus router logs only locally and loses fault evidence after flash rotation, despite a requirement for long-term security investigation; this alternative would address the wrong dependency.

Overly aggressive polling can consume limited control-plane CPU and management bandwidth without improving decision quality. “Select telemetry collection intervals and methods proportional to observed change rates and device capacity” would remedy that alternative situation, but it would not correct the present issue: central monitoring infrastructure can become a single point of failure even when individual access devices have redundant uplinks.

“Design correct multicast reverse paths and compatible unicast routing so upstream interfaces pass the RPF check” is the supported response when multicast RPF typically checks the route back toward the source or RP, not merely whether a receiver destination is reachable. Here the decisive response is “Design appropriate collector and transport redundancy with supported failover and secure retention behavior”, 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 national enterprise sends every configuration backup and log to one management collector in a single data center with no alternate destination; this alternative would address the wrong dependency.