Cisco 300-420 Bundle

That change concerns sd wan edge last mile diversity, where Logical dual-circuit contracts may share a physical access path and suffer a common-cause outage. The reported issue instead stems from: A purely hub-and-spoke forwarding policy can add latency and load when the DMVPN design is intended to allow direct spoke shortcuts.

That change concerns cloud wan direct private connectivity choice, where An encrypted Internet overlay does not provide the same private carrier connectivity, SLA and traffic-engineering options as a qualified dedicated cloud circuit. In this question the necessary remedy is “Use a supported DMVPN phase and NHRP routing design that safely establishes eligible spoke-to-spoke tunnels”, which this alternative does not provide.

That change concerns ipsec encryption versus gre transport, where GRE provides encapsulation for multiple protocols but does not itself encrypt or authenticate payload confidentiality. The observed condition is a national enterprise uses a DMVPN hub for branch IPsec tunnels but all branch-to-branch voice calls hairpin through the distant hub despite viable direct underlay paths; this mechanism addresses another problem.

Without deliberate STP root design, Layer 2 forwarding paths may traverse inappropriate access hardware. “Set primary and backup STP roots on appropriate distribution devices and validate bridge priority and path costs” would remedy that alternative situation, but it would not correct the present issue: a fabric control plane supplies locator information, while the data plane uses supported VXLAN encapsulation to carry endpoint traffic.

“Provision eligible access devices as supported fabric edge nodes and verify host onboarding and virtual network assignments” is the supported response when ordinary underlay reachability does not assign endpoint onboarding and VXLAN edge functions to a nonfabric access device. Here the decisive response is “Design overlay forwarding paths with validated VXLAN reachability, fabric edge encapsulation and proper transport MTU”, so that different intervention does not meet the stated requirement.

Fabric overlay encapsulation adds overhead beyond ordinary IP reachability and depends on a healthy L3 underlay. “Provide resilient IP underlay reachability and adequate end-to-end MTU for supported fabric encapsulation” applies to that other condition. The reported evidence is a campus engineer describes LISP mapping updates as the mechanism transporting user data between fabric edges and neglects overlay tunnel reachability; this alternative would address the wrong dependency.

That change concerns ipv6 security policy parity, where IPv4-only security rules do not automatically enforce the same trust boundary for IPv6 traffic on a dual-stack path. The reported issue instead stems from: External Type 2 cost behavior does not account for internal cost in the same way as Type 1 when external metrics differ.

That change concerns ospf area 0 resilient backbone, where OSPF hierarchical inter-area connectivity depends on a stable backbone design and resilient area border connectivity. In this question the necessary remedy is “Select E1 or E2 route treatment to reflect the required exit preference, testing both external and internal metrics”, which this alternative does not provide.

That change concerns ospf stub area external lsa control, where A normal area floods external routing information that stub-capable branches may not need when a default route is sufficient. The observed condition is a redistribution design sends external OSPF Type 2 routes across sites with very different internal transit costs, yet expects remote sites to prefer the closest exit; this mechanism addresses another problem.

Carrier detection at the local switch does not necessarily detect loss of a remote routed neighbor or intermediate path. “Design suitable BFD sessions for supported routing peers with conservative scale-aware timer settings” would remedy that alternative situation, but it would not correct the present issue: bidirectional multipoint redistribution without route tagging or authoritative direction can reintroduce routes into their source protocol.

“Design supported VRF-lite routing instances with carefully governed shared-services connectivity and separate interface assignments” is the supported response when a common routing instance cannot enforce independent overlapping IP destinations and controlled route exposure by itself. Here the decisive response is “Apply explicit redistribution filters, tags, metrics and domain ownership at each boundary with deliberate failure fallback”, so that different intervention does not meet the stated requirement.

Extending Layer 2 broadly across campus buildings increases loop, convergence and failure-domain exposure. “Design routed access where supported, using local Layer 3 boundaries and deterministic IGP connectivity between buildings” applies to that other condition. The reported evidence is two campus cores exchange OSPF and EIGRP routes across two border routers and route entries recirculate until suboptimal paths appear; this alternative would address the wrong dependency.

Graceful restart depends on both peers' supported capabilities and bounded stale-route handling, not merely a routing session name. “Test graceful-restart interactions with BFD and forwarding readiness during platform changes” would remedy that alternative situation, but it would not correct the present issue: an IPv4-only underlay cannot natively carry IPv6 forwarding without an overlay or other transition capability.

“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 “Monitor tunnel endpoint resilience and account for encapsulation overhead in path MTU design”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is a branch runs IPv6-only management endpoints over a provider transport that supports IPv4 underlay only, but the design expects native IPv6 routing to work end to end; this alternative would address the wrong dependency.

Logical dual-circuit contracts may share a physical access path and suffer a common-cause outage. “Choose WAN edge circuits with validated last-mile, provider and facility diversity where the service recovery target requires it” 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.

“Create supported application-aware routing policy with validated SLA class thresholds and fallback behavior” 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 “Choose a supported multicast distribution and replication approach with measured receiver count and transport constraints”, so that different intervention does not meet the stated requirement.

Remote-only controller dependencies and insufficient regional capacity can degrade onboarding, resiliency and convergence at scale. “Design supported regional controller and overlay architecture with redundancy, policy consistency and documented capacity limits” 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.

Multihoming and address translation must account for both directions; outbound route changes alone may not preserve return paths. “Test full transactions and reverse paths, not only traceroutes leaving the branch WAN edge” 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.

“Test delay-sensitive applications on each planned failover path before approving WAN topology” 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 “Review transport and security policy together whenever adding a new Internet link”, 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. “Report both normal and degraded capacity forecasts when approving enterprise WAN budgets” 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.

Carrier detection at the local switch does not necessarily detect loss of a remote routed neighbor or intermediate path. “Design suitable BFD sessions for supported routing peers with conservative scale-aware timer settings” would remedy that alternative situation, but it would not correct the present issue: a virtualized or stacked switching design needs supported control, state and multichassis link mechanisms to act as one logical system.

“Set primary and backup STP roots on appropriate distribution devices and validate bridge priority and path costs” is the supported response when without deliberate STP root design, Layer 2 forwarding paths may traverse inappropriate access hardware. Here the decisive response is “Select a validated stacking or virtual-switch architecture and plan supervisor, interconnect and software compatibility”, 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 two distribution switches are intended to behave as one logical platform, but engineers assume separate independent control planes deliver the same cross-chassis link semantics; this alternative would address the wrong dependency.

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” 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.

“Use optical engineering validation rather than treating wavelength transport as simple Ethernet aggregation” is the supported response when ordinary port-level upgrades may not meet aggregate fiber-capacity and distance requirements when the optical transport must host many independent wavelengths. Here the decisive response is “Assess broadcast extension failure domains before buying a transparent transport solely to avoid route design”, so that different intervention does not meet the stated requirement.

Multipoint Ethernet services and many independent E-Line circuits have different Layer 2 forwarding and spanning-tree implications. “Document E-Line versus E-LAN service boundaries and operational responsibility with the provider” 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.

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: typical Ethernet SLAAC uses /64 interface identifiers and ordinary host autoconfiguration expectations are not met by arbitrary longer access prefixes.

“Document ULA-to-global boundaries and ensure policies and DNS do not accidentally expose internal-only IPv6 addresses” is the supported response when provider-dependent global prefixes may require renumbering when upstream connectivity changes and do not replace a stable local-only design. Here the decisive response is “Validate IPv6 prefix lengths against actual endpoint SLAAC and Neighbor Discovery requirements before deployment”, so that different intervention does not meet the stated requirement.

Network dual stacking alone does not add AAAA DNS records, IPv6 listening services, security policy or path validation to existing applications. “Treat IP family readiness as an end-to-end application acceptance gate rather than a router-interface checkbox” applies to that other condition. The reported evidence is a network designer attempts to conserve an enterprise /48 by assigning IPv6 /80 prefixes to ordinary SLAAC user LANs, then reports that standard hosts fail autoconfiguration; this alternative would address the wrong dependency.

Local log storage and rollover cannot substitute for reliable centralized timestamped security event retention. “Design redundant remote syslog collectors with protected transport, appropriate facilities and retention controls” would remedy that alternative situation, but it would not correct the present issue: in-band-only management can share a fault with the network being repaired, eliminating the ability to recover remotely.

“Classify authentic management flows and allocate controlled minimum service within the WAN's QoS policy” is the supported response when without proper management traffic classification and minimum bandwidth, congestion can starve necessary operations traffic. Here the decisive response is “Provide secure out-of-band management through independent transport, power and authentication suitable for critical nodes”, so that different intervention does not meet the stated requirement.

Legacy community strings do not provide SNMPv3's user-based authentication and encryption capabilities needed by the policy. “Design supported SNMPv3 users, auth/privacy mechanisms, least-privilege views and central credential lifecycle” applies to that other condition. The reported evidence is a distributed business manages core routers only through their production VPN, and a routing incident removes both business forwarding and remote admin access; this alternative would address the wrong dependency.