Cisco 300-420 Bundle

That change concerns multicast rp address placement strategy, where RP location affects shared-tree path efficiency and control resilience for ASM groups and can create a remote common-mode dependency. The reported issue instead stems from: Naive replicated unicast can consume far more shared-link capacity than a suitable multicast tree for many receivers.

That change concerns multicast boundary group filtering, where Without explicit multicast boundary control, group advertisements or forwarding may extend beyond authorized trust domains. In this question the necessary remedy is “Assess multicast replication at branching points or other supported content distribution design with receiver policy”, which this alternative does not provide.

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 observed condition is a regional network distributes one 20 Mbps live event to sixty branches by sending sixty independent copies across the same core link; this mechanism addresses another problem.

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” would remedy that alternative situation, but it would not correct the present issue: overlapping address spaces are ambiguous to ordinary destination-based routing and require unique addressing or deliberate translation boundaries.

“Require automated prefix containment and component-reachability validation on every proposed aggregate route advertisement” is the supported response when a /15 covers two consecutive aligned /16 networks and the selected /15 omits 10.66.0.0/16 while including unintended space. Here the decisive response is “Perform overlap detection in IPAM during mergers and document all temporary translation rules and decommissioning milestones”, so that different intervention does not meet the stated requirement.

Randomly scattered branch subnets prevent region-level summarization and make routing and change control unnecessarily complex. “Use an authoritative IP address management registry with reservation, collision checks and explicit aggregation ownership for new sites” applies to that other condition. The reported evidence is a newly acquired company uses 10.12.0.0/16, already used at headquarters, and an engineer proposes direct site-to-site routing between both unmodified networks; this alternative would address the wrong dependency.

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 non-designated STP port losing expected control messages can create a loop if it incorrectly assumes the superior path vanished.

That change concerns per vlan stp scalability, where A per-VLAN spanning-tree model scales protocol state with VLAN count and may become less efficient than suitable aggregated instances. In this question the necessary remedy is “Use Loop Guard on appropriate non-edge STP links and deploy complementary unidirectional link detection where supported”, 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 one of two redundant STP links stops receiving BPDUs due to a unidirectional fault but remains physically up, risking a blocked port transitioning to forwarding; this mechanism addresses another problem.

Machine-readable data model revisions and capabilities can differ across platform versions even if management connectivity remains healthy. “Read supported YANG module revisions and capabilities and implement controlled schema compatibility or versioned adapters” would remedy that alternative situation, but it would not correct the present issue: standardized models do not necessarily represent every vendor-specific operational or configuration feature.

“Select supported OpenConfig telemetry modules, verify revisions and normalize exceptions without assuming universal coverage” is the supported response when openConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform. Here the decisive response is “Use the supported Cisco native YANG model for the particular feature with platform and software-version capability checks”, 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 controller needs to configure a specialized Cisco-only feature not represented by its generic OpenConfig model, yet developers insist the generic model must support it; this alternative would address the wrong dependency.

A conventional port channel cannot span unrelated independent switches without a supported multichassis or stacking mechanism. “Prove peer-link, keepalive and split-brain failure behavior before choosing dual-chassis aggregation” would remedy that alternative situation, but it would not correct the present issue: without port security or identity-aware access control, a simple access port may learn multiple endpoint MAC addresses without limitation.

“Track real endpoint power profiles and spare capacity during access switch procurement” is the supported response when available PoE power budget and per-port capabilities determine whether simultaneous endpoint power requirements can be met. Here the decisive response is “Align MAC limit exceptions with phones, hypervisors and other genuine multi-MAC endpoints”, so that different intervention does not meet the stated requirement.

EtherChannel members need compatible Layer 2 settings and negotiated bundling state to represent a correct logical link. “Audit allowed VLANs and link settings at both ends when adding or replacing bundle members” applies to that other condition. The reported evidence is a user port should admit one registered device but an unmanaged bridge with several MAC addresses is connected, and the switch admits all sources; this alternative would address the wrong dependency.

Encapsulation and encryption overhead reduce effective path MTU, and missing PMTUD control messages can stall large packets. “Include maximum-frame and PMTU tests in every overlay transport acceptance plan” would remedy that alternative situation, but it would not correct the present issue: local breakout bypasses central inspection unless equivalent secure edge controls and policy are deliberately placed.

“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 “Treat breakout decisions as combined WAN and security design approvals rather than routing-only changes”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is a branch enables direct SaaS Internet breakout to improve performance but the original design assumes all egress is filtered by the data center firewall; this alternative would address the wrong dependency.

Routing graceful restart requires compatible neighbor capability and safe stale-route lifetimes, not merely redundant uplinks. “Use supported graceful restart and nonstop forwarding features only where peer compatibility and forwarding state can be verified” would remedy that alternative situation, but it would not correct the present issue: fabric control-plane endpoint-to-location mapping must reflect movement and be consistent with current host registration.

“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 “Use supported redundant LISP control-plane nodes and verify endpoint registration and mapping refresh behavior”, so that different intervention does not meet the stated requirement.

A fabric control plane supplies locator information, while the data plane uses supported VXLAN encapsulation to carry endpoint traffic. “Design overlay forwarding paths with validated VXLAN reachability, fabric edge encapsulation and proper transport MTU” applies to that other condition. The reported evidence is a fabric edge learns an endpoint address but forwards to an old location after the endpoint moves between buildings because its mapping data is stale; this alternative would address the wrong dependency.

That change concerns qos per interface policy direction, where Input classification and policing operate on traffic entering an interface, while output scheduling applies to egress congestion. The reported issue instead stems from: Average throughput can hide instantaneous bursts and delay variation that disrupt real-time media even when link utilization seems moderate.

That change concerns qos validation with actual queue counters, where A syntactically installed QoS policy does not establish that actual applications match intended classes or receive required forwarding treatment. In this question the necessary remedy is “Reserve suitable queue and burst tolerance based on codec behavior, media priority and empirically observed peak load”, which this alternative does not provide.

That change concerns qos class map matching order, where Traffic classification order and policy constructs can cause broad conditions to overshadow intended more-specific class handling. The observed condition is interactive training video experiences brief rate bursts, and engineers allocate only average bitrate with no jitter or loss allowance across the WAN; this mechanism addresses another problem.

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: multicast RPF typically checks the route back toward the source or RP, not merely whether a receiver destination is reachable.

“Use resilient approved NTP sources with authenticated or trusted network delivery where supported” is the supported response when uncoordinated system clocks undermine log chronology, audit correlation and incident reconstruction. Here the decisive response is “Design correct multicast reverse paths and compatible unicast routing so upstream interfaces pass the RPF check”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is a multicast receiver sees no video even though the router has a unicast route to the receiver, and engineers inspect only destination forwarding; this alternative would address the wrong dependency.

Layer 1 carrier state may not reveal a downstream path failure and slow neighbor detection extends blackhole time. “Capacity-plan BFD session counts and monitor instability before enabling aggressive timers across large deployments” would remedy that alternative situation, but it would not correct the present issue: a BGP TCP session does not automatically negotiate or advertise every address family without appropriate capabilities and policy.

“Document OSPF network-type assumptions and test peer compatibility during link-provider migrations” is the supported response when default broadcast OSPF network behavior can elect designated routers even when the topology is only a two-router link. Here the decisive response is “Include negotiated address-family and next-hop checks in every BGP peer acceptance procedure”, so that different intervention does not meet the stated requirement.

Unrestricted BGP export policy exposes destinations not authorized for upstream announcement and risks routing leaks. “Perform automated prefix allowlist tests and route-leak simulations before modifying BGP transit peers” applies to that other condition. The reported evidence is two enterprise BGP routers establish a TCP session and exchange IPv4 reachability but their IPv6 networks remain absent after enabling the underlying IPv6 interface; 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. “Budget tunnel overhead in MTU planning, preserve required ICMPv6 control messages and validate endpoints' segment sizes” would remedy that alternative situation, but it would not correct the present issue: BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic.

“Choose an aggregate policy with reviewed component-route dependencies, conservative discard behavior and correct reachability design” 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 “Evaluate path attributes and supported multipath settings, then choose a design that preserves deterministic failover”, 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. “Use a supported IPv6-over-IPv4 tunnel with correct endpoint reachability, encapsulation security and effective MTU” applies to that other condition. The reported evidence is an edge device has two BGP paths to the same prefix but operators expect load sharing merely because both routes appear in the neighbor table; this alternative would address the wrong dependency.