Cisco 300-420 Bundle

That change concerns udld fiber bidirectional verification, where Physical link-up is insufficient to guarantee bidirectional signal integrity, which can affect control-plane protocols and forwarding. The reported issue instead stems from: A per-VLAN spanning-tree model scales protocol state with VLAN count and may become less efficient than suitable aggregated instances.

That change concerns stp root guard toward untrusted switch, where Superior BPDUs on an untrusted downstream link can alter STP root selection unless the boundary is protected. In this question the necessary remedy is “Assess MST or Layer 3 access boundaries against actual traffic steering and availability requirements”, which this alternative does not provide.

That change concerns mst region boundary mismatch, where MST region membership requires consistent region identifier, revision and VLAN mapping rather than matching only some VLAN names. The observed condition is a campus uses hundreds of VLANs with distinct rapid spanning-tree instances and experiences growing CPU and change-control complexity; this mechanism addresses another problem.

Uncontrolled bidirectional redistribution can reintroduce routes, create loops and lose source-of-truth route preference. “Use explicit tag-based redistribution policy, defined metrics and directional filters at well-documented borders” would remedy that alternative situation, but it would not correct the present issue: neighbor authentication parameters and permitted key windows must align or the routing protocol rejects peer messages.

“Review reported and feasible distances and design valid loop-free alternatives rather than forcing an invalid candidate” is the supported response when an EIGRP feasible successor must satisfy its feasibility condition relative to the successor's feasible distance to prevent loops. Here the decisive response is “Coordinate supported EIGRP authentication changes and key rollover across both peers with safe cutover”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is two enterprise EIGRP neighbors cease exchanging routes after only one endpoint changes key identifiers during security hardening; this alternative would address the wrong dependency.

That change concerns cloud direct connect redundant circuits, where Logical network separation on one physical direct-connect facility does not eliminate common power, provider or meet-me-room failures. The reported issue instead stems from: OpenConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform.

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. In this question the necessary remedy is “Select supported OpenConfig telemetry modules, verify revisions and normalize exceptions without assuming universal coverage”, which this alternative does not provide.

That change concerns YANG schema revision and path versioning, where Machine-readable data model revisions and capabilities can differ across platform versions even if management connectivity remains healthy. The observed condition 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 mechanism addresses another problem.

Neighbor authentication parameters and permitted key windows must align or the routing protocol rejects peer messages. “Coordinate supported EIGRP authentication changes and key rollover across both peers with safe cutover” would remedy that alternative situation, but it would not correct the present issue: EIGRP unequal-cost load sharing is not enabled simply because multiple routes exist and is constrained by feasibility and variance.

“Review reported and feasible distances and design valid loop-free alternatives rather than forcing an invalid candidate” is the supported response when an EIGRP feasible successor must satisfy its feasibility condition relative to the successor's feasible distance to prevent loops. Here the decisive response is “Assess feasible successors and apply an approved variance design with realistic traffic-share expectations”, so that different intervention does not meet the stated requirement.

Uncontrolled bidirectional redistribution can reintroduce routes, create loops and lose source-of-truth route preference. “Use explicit tag-based redistribution policy, defined metrics and directional filters at well-documented borders” applies to that other condition. The reported evidence is a regional hub has a primary 100 Mbps path and secondary 50 Mbps path and wants controlled EIGRP unequal-cost use, but the default setting installs only equal-cost routes; this alternative would address the wrong dependency.

Logical network separation on one physical direct-connect facility does not eliminate common power, provider or meet-me-room failures. “Design redundant cloud interconnects with suitable facility diversity, BGP and controlled Internet or secondary private fallback” would remedy that alternative situation, but it would not correct the present issue: a hybrid deployment can transfer sensitive data or metadata across administrative and geographic boundaries even when application compute stays on-premises.

“Choose a suitable SaaS, PaaS or IaaS architecture with an explicit responsibility matrix for app, identity, runtime and infrastructure” is the supported response when cloud service models allocate operational responsibility differently; consuming PaaS normally shifts underlying host management while retaining customer data and access duties. Here the decisive response is “Design controlled hybrid data flow, regional placement and access policies that satisfy residency and connectivity requirements”, 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 an enterprise has customer records that must remain in a private data center but moves its analytics control plane to a public cloud SaaS service without examining metadata export; this alternative would address the wrong dependency.

In-band-only management can share a fault with the network being repaired, eliminating the ability to recover remotely. “Test the independent OOB path and break-glass credentials during scheduled resilience drills” would remedy that alternative situation, but it would not correct the present issue: a common routing table broadens the management attack surface and increases risk of route or ACL leakage.

“Rotate SNMPv3 credentials and test monitoring continuity across device replacements” is the supported response when legacy community strings do not provide SNMPv3's user-based authentication and encryption capabilities needed by the policy. Here the decisive response is “Audit management route import and export policy after topology changes and disaster recovery tests”, so that different intervention does not meet the stated requirement.

Local log storage and rollover cannot substitute for reliable centralized timestamped security event retention. “Review logging health and retention policy across all management routing contexts” applies to that other condition. The reported evidence is an enterprise puts SNMP, SSH and backup traffic in the same global routing table as public guest endpoints, complicating access restrictions; this alternative would address the wrong dependency.

A summary advertised by a border without valid components can attract and blackhole traffic during partial network failures. “Tie aggregate advertisement to required downstream reachability or redesign summarization and redundancy accordingly” 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.

“Select a topology and route policy that maintain suitable symmetric inspected paths or supported state sharing” is the supported response when stateful inspection needs coherent bidirectional flow visibility, while independent routing cost choices can create asymmetric paths. Here the decisive response is “Align appropriate IGP costs and supported equal-cost multipath settings with capacity and symmetric path requirements”, 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. “Export only authorized service prefixes and apply necessary packet access restrictions at the shared-services border” 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.

Static transport preference does not substitute for application-aware path decisions using measured latency, loss and jitter. “Create supported application-aware routing policy with validated SLA class thresholds and fallback behavior” would remedy that alternative situation, but it would not correct the present issue: encapsulation and encryption overhead reduce effective path MTU, and missing PMTUD control messages can stall large packets.

“Evaluate supported GET VPN group key distribution and policy design where technology and business requirements fit” is the supported response when traditional point-to-point encryption tunnel meshes may add unnecessary topology and scale complexity for a trusted private routed underlay. Here the decisive response is “Budget tunnel overhead, validate tunnel MTU/MSS adjustment and preserve necessary ICMP feedback”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is a branch adds GRE over IPsec and experiences intermittent large-file transfer failures even though small test pings work; this alternative would address the wrong dependency.

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” would remedy that alternative situation, but it would not correct the present issue: network dual stacking alone does not add AAAA DNS records, IPv6 listening services, security policy or path validation to existing applications.

“Review IS-IS level boundaries whenever branch count grows or a site moves between geographic areas” is the supported response when IS-IS Level 1 operates within an area while Level 2 provides inter-area connectivity and should bound unwanted topology flooding. Here the decisive response is “Treat IP family readiness as an end-to-end application acceptance gate rather than a router-interface checkbox”, so that different intervention does not meet the stated requirement.

Typical Ethernet SLAAC uses /64 interface identifiers and ordinary host autoconfiguration expectations are not met by arbitrary longer access prefixes. “Validate IPv6 prefix lengths against actual endpoint SLAAC and Neighbor Discovery requirements before deployment” applies to that other condition. The reported evidence is a company turns on IPv6 routing at its branch WAN edge but assumes every application automatically supports IPv6 even though several server DNS records and firewall policies remain IPv4-only; this alternative would address the wrong dependency.

An unsegmented overlay routing context can make trust-boundary errors more likely even if some edge access rules exist. “Review VPN to VRF mapping and centralized policy whenever adding new tenant classes” would remedy that alternative situation, but it would not correct the present issue: naive unicast replication can consume excessive WAN capacity, while multicast support depends on platform and overlay design.

“Review application SLAs and measurement probes after changing WAN providers or regional geography” is the supported response when static transport preference does not substitute for application-aware path decisions using measured latency, loss and jitter. Here the decisive response is “Test multicast behavior and failure recovery with representative audience sizes before production events”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is a corporate town hall multicast stream must reach dozens of remote branches, but the design duplicates full-rate unicast copies at every WAN hop; 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: Without class-based queue service, different traffic priorities may compete equally under congestion rather than receiving guaranteed minimum allocations.

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. In this question the necessary remedy is “Implement appropriate CBWFQ or platform-supported scheduler weights after classifying actual traffic”, which this alternative does not provide.

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 observed condition is a WAN link has three business traffic classes but the design uses only a best-effort FIFO queue, creating unpredictable delay during peaks; this mechanism addresses another problem.