Cisco 300-420 Bundle

Bidirectional multipoint redistribution without route tagging or authoritative direction can reintroduce routes into their source protocol. “Apply explicit redistribution filters, tags, metrics and domain ownership at each boundary with deliberate failure fallback” would remedy that alternative situation, but it would not correct the present issue: MST region membership requires consistent region identifier, revision and VLAN mapping rather than matching only some VLAN names.

“Enable appropriate UDLD modes on supported fiber links and validate shutdown and recovery procedures” is the supported response when physical link-up is insufficient to guarantee bidirectional signal integrity, which can affect control-plane protocols and forwarding. Here the decisive response is “Align approved MST region configuration and verify boundary ports and per-instance root placement”, so that different intervention does not meet the stated requirement.

A per-VLAN spanning-tree model scales protocol state with VLAN count and may become less efficient than suitable aggregated instances. “Assess MST or Layer 3 access boundaries against actual traffic steering and availability requirements” applies to that other condition. The reported evidence is two campus buildings should share one MST region but have different region names or VLAN-to-instance maps, unexpectedly changing STP behavior at the boundary; this alternative would address the wrong dependency.

Central monitoring infrastructure can become a single point of failure even when individual access devices have redundant uplinks. “Design appropriate collector and transport redundancy with supported failover and secure retention behavior” would remedy that alternative situation, but it would not correct the present issue: naive replicated unicast can consume far more shared-link capacity than a suitable multicast tree for many receivers.

“Choose strategically located and redundant RPs considering source and receiver topology, routing cost and failover” is the supported response when RP location affects shared-tree path efficiency and control resilience for ASM groups and can create a remote common-mode dependency. Here the decisive response is “Assess multicast replication at branching points or other supported content distribution design with receiver policy”, so that different intervention does not meet the stated requirement.

Without explicit multicast boundary control, group advertisements or forwarding may extend beyond authorized trust domains. “Apply supported multicast group or source boundary filtering at the appropriate WAN and tenant interfaces” applies to that other condition. The reported evidence is a regional network distributes one 20 Mbps live event to sixty branches by sending sixty independent copies across the same core link; this alternative would address the wrong dependency.

Multicast RPF typically checks the route back toward the source or RP, not merely whether a receiver destination is reachable. “Design correct multicast reverse paths and compatible unicast routing so upstream interfaces pass the RPF check” 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 supported redundant RP mechanisms with consistent group mappings and reachability across the multicast domain” is the supported response when ASM shared-tree setup may depend on reachable RP control functions that need deliberate redundancy. 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.

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” 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.

BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic. “Reassess multipath qualification whenever route attributes, providers or platform software change” would remedy that alternative situation, but it would not correct the present issue: manual per-prefix policy misses newly onboarded routes when attributes and export rules are not centrally classified.

“Audit aggregate announcements and child route health before and after regional outages” 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 “Govern community naming, collision avoidance and route-leak tests across all border routers”, so that different intervention does not meet the stated requirement.

An IPv4-only underlay cannot natively carry IPv6 forwarding without an overlay or other transition capability. “Monitor tunnel endpoint resilience and account for encapsulation overhead in path MTU design” applies to that other condition. The reported evidence is an enterprise requires certain partner routes never to be announced to public Internet peers but currently filters using manually maintained individual prefixes only; this alternative would address the wrong dependency.

That change concerns glbp unequal gateway load sharing, where Traditional active-standby first-hop redundancy does not by itself provide the desired per-client gateway load distribution. The reported issue instead stems from: FHRP presence alone may not account for upstream path viability without appropriate object or interface tracking.

That change concerns vrrp preempt restoration behavior, where Gateway role restoration depends on the selected FHRP protocol and its configured preemption settings, not priority numbers alone. In this question the necessary remedy is “Track the required upstream path and decrement priority enough for a healthy standby gateway to assume forwarding”, which this alternative does not provide.

That change concerns hsrp split brain and vlan consistency, where FHRP peers must exchange control messages in a correctly shared VLAN to maintain a single active forwarding role. The observed condition is a campus HSRP active router loses its WAN uplink but keeps its local VLAN interface up, so users keep sending packets to a gateway that cannot exit the site; this mechanism addresses another problem.

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: overlay headers reduce usable path MTU and blocked ICMPv6 Packet Too Big feedback can prevent Path MTU Discovery.

“Record transition architecture decision criteria instead of applying one translation model to every workload” is the supported response when translation adds stateful dependencies and application edge cases that may be unnecessary when a controlled native dual-stack phase is viable. Here the decisive response is “Include tunnel and encryption overhead in WAN design capacity and test plans”, so that different intervention does not meet the stated requirement.

IPv4-only security rules do not automatically enforce the same trust boundary for IPv6 traffic on a dual-stack path. “Include IPv6 policy and telemetry reviews in every dual-stack readiness audit” applies to that other condition. The reported evidence is a dual-stack application works with small IPv6 probes through a GRE overlay but stalls on larger encrypted payloads after tunnel encapsulation; this alternative would address the wrong dependency.

Logical transport labels or TLOCs do not inherently represent independent circuits, carrier facilities or last-mile paths. “Map TLOCs to genuinely diverse approved transport interfaces and validate policy-based failover” would remedy that alternative situation, but it would not correct the present issue: secure SD-WAN fabric admission requires authorized organization identifiers and valid identity trust, not just IP routing.

“Design redundant supported SD-WAN Managers with backup, RBAC and regional management reachability as appropriate” is the supported response when management availability and existing data-plane forwarding have different dependencies, while loss of manageability remains an operational risk. Here the decisive response is “Design approved CA trust, certificate lifecycle and device authorization procedures for every control node and edge”, so that different intervention does not meet the stated requirement.

Data-plane tunnel presence does not guarantee that control-plane route advertisement and segmentation policy deliver needed service prefixes. “Validate OMP route advertisements and centralized policy across controllers with intended VPN and TLOC eligibility” applies to that other condition. The reported evidence is a new SD-WAN edge has Internet reachability but cannot join the fabric because controller identity and certificate chain checks are not satisfied; this alternative would address the wrong dependency.

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 reported issue instead stems from: A common routing instance cannot enforce independent overlapping IP destinations and controlled route exposure by itself.

That change concerns multicampus route summarization boundary, where Missing site-level address summarization increases routing state and exposes the WAN to local campus topology churn. In this question the necessary remedy is “Design supported VRF-lite routing instances with carefully governed shared-services connectivity and separate interface assignments”, which this alternative does not provide.

That change concerns mutual redistribution loop prevention, where Bidirectional multipoint redistribution without route tagging or authoritative direction can reintroduce routes into their source protocol. The observed condition is guest kiosks and regulated finance terminals share one campus routing table despite requirements that their overlapping address blocks remain isolated; this mechanism addresses another problem.

That change concerns sd access border transit between fabrics, where Physical underlay IP connectivity does not by itself establish appropriate inter-fabric transit, route exchange and segmentation policy. The reported issue instead stems from: Link redundancy within the fabric does not guarantee sufficient external border forwarding capacity during degraded operation.

That change concerns sd access extended node role boundaries, where Extended nodes and ordinary fabric nodes have distinct supported roles and scale limits; uplink connection alone does not confer every fabric service. In this question the necessary remedy is “Size border nodes and redundant exits for N-minus-one load, applying failure-domain and traffic-engineering requirements”, which this alternative does not provide.

That change concerns sd access fabric wireless integration, where Fabric wireless requires supported controller and edge integration and consistent segmentation assignments for mobile clients. The observed condition is a fabric design has redundant edge uplinks but no redundant border capacity, so a single border failure overloads the remaining exit path; this mechanism addresses another problem.

Multihoming and address translation must account for both directions; outbound route changes alone may not preserve return paths. “Design consistent BGP advertisement, NAT and routing failover so return flows follow the reachable secondary path” would remedy that alternative situation, but it would not correct the present issue: a hybrid WAN needs explicit route and security decisions because reachability alone does not guarantee sensitive traffic uses approved paths.

“Design supported Catalyst SD-WAN orchestrator reachability and certificate trust separately from data-plane transport tunnels” is the supported response when the orchestration function helps WAN edges discover and authenticate to the fabric but should not be placed in the regular data forwarding path. Here the decisive response is “Classify traffic by trust and business criticality and apply supported routing or SD-WAN policies for each transport”, so that different intervention does not meet the stated requirement.

Bandwidth alone does not determine application suitability when propagation delay and jitter exceed interactive service limits. “Choose appropriate low-latency WAN transport and QoS treatment, evaluating cost, resilience and route diversity” applies to that other condition. The reported evidence is a business retains MPLS for regulated transactional traffic but adds low-cost Internet transport and advertises all private prefixes across both transports without selection policy; this alternative would address the wrong dependency.

That change concerns eigrp unequal cost traffic sharing, where EIGRP unequal-cost load sharing is not enabled simply because multiple routes exist and is constrained by feasibility and variance. The reported issue instead stems from: An EIGRP feasible successor must satisfy its feasibility condition relative to the successor's feasible distance to prevent loops.

That change concerns eigrp route summarization at hub, where Unnecessary specific-route propagation increases state and change sensitivity without providing required central policy detail. In this question the necessary remedy is “Review reported and feasible distances and design valid loop-free alternatives rather than forcing an invalid candidate”, which this alternative does not provide.

That change concerns eigrp hub topology route leaking, where Uncontrolled bidirectional redistribution can reintroduce routes, create loops and lose source-of-truth route preference. The observed condition is an enterprise asks EIGRP to install an alternate path solely because the alternate advertised distance is low, without checking the feasibility condition; this mechanism addresses another problem.