Cisco 300-420 Bundle

Stateful inspection needs coherent bidirectional flow visibility, while independent routing cost choices can create asymmetric paths. “Include reverse-path verification in campus security zone design and ECMP changes” would remedy that alternative situation, but it would not correct the present issue: a summary advertised by a border without valid components can attract and blackhole traffic during partial network failures.

“Establish timer and session-count budgets per platform before promising uniform subsecond convergence” is the supported response when high session counts and excessively aggressive timers can exhaust control resources and cause false routing flaps. Here the decisive response is “Test partial reachability failures, not only complete router outages, when validating multicampus route policy”, 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. “Audit shared services route leaks and ACLs together after each tenant or service onboarding” applies to that other condition. The reported evidence is two redundant campus borders advertise the same summary but only one border has reachability to the specific server block after an internal partition; this alternative would address the wrong dependency.

That change concerns cisco sd wan management plane resilience, where Management availability and existing data-plane forwarding have different dependencies, while loss of manageability remains an operational risk. The reported issue instead stems from: VPN session status can be healthy while mismatched crypto ACLs or traffic selectors omit the application flow.

That change concerns get vpn any to any encryption, where Traditional point-to-point encryption tunnel meshes may add unnecessary topology and scale complexity for a trusted private routed underlay. In this question the necessary remedy is “Update both peers' protected prefix definitions and routing design with least-privilege permitted flows”, which this alternative does not provide.

That change concerns gre tunnel mtu and fragmentation, where Encapsulation and encryption overhead reduce effective path MTU, and missing PMTUD control messages can stall large packets. The observed condition is a site-to-site tunnel negotiates successfully but finance traffic fails because protected subnet traffic selectors exclude one new destination prefix; this mechanism addresses another problem.

That change concerns is-is wide metric consistency, where Mixed or unsuitable metric styles can undermine consistent path-cost planning and overflow the intended metric range. The reported issue instead stems from: BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic.

That change concerns BGP community-based export policy, where Manual per-prefix policy misses newly onboarded routes when attributes and export rules are not centrally classified. In this question the necessary remedy is “Evaluate path attributes and supported multipath settings, then choose a design that preserves deterministic failover”, which this alternative does not provide.

That change concerns ipv6 gre overlay across ipv4 underlay, where An IPv4-only underlay cannot natively carry IPv6 forwarding without an overlay or other transition capability. The observed condition 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 mechanism addresses another problem.

Standardized models do not necessarily represent every vendor-specific operational or configuration feature. “Use the supported Cisco native YANG model for the particular feature with platform and software-version capability checks” would remedy that alternative situation, but it would not correct the present issue: vendor-native data models may expose platform-specific schema that cannot be queried identically across different vendors.

“Design a supported NETCONF workflow with lock, edit-config, validate, commit and rollback handling for the device capabilities” is the supported response when NETCONF can expose candidate datastores, locking and commit operations where supported, unlike assuming every management interface has equivalent transactions. Here the decisive response is “Prefer a suitable standards-based IETF model for portable interface telemetry, documenting implementation gaps and vendor extensions”, so that different intervention does not meet the stated requirement.

OpenConfig provides vendor-neutral model definitions whose implemented paths and capabilities must still be validated per platform. “Select supported OpenConfig telemetry modules, verify revisions and normalize exceptions without assuming universal coverage” applies to that other condition. The reported evidence is a national enterprise must collect interface statistics from routers supplied by three vendors, but a developer builds everything against one Cisco-proprietary YANG path; this alternative would address the wrong dependency.

Random early detection is usually better aligned with responsive TCP queues than with high-priority delay-sensitive voice traffic. “Use appropriate congestion avoidance on suitable best-effort TCP classes and protect voice through controlled priority service” would remedy that alternative situation, but it would not correct the present issue: encryption hides much application payload from intermediate classifiers, so deep packet inspection may not see per-app content inside the tunnel.

“Design call admission or session limits based on codec overhead and failover bandwidth, with controlled class policies” is the supported response when priority queuing alone cannot create bandwidth beyond circuit capacity, and too many concurrent sessions can oversubscribe voice allocation. Here the decisive response is “Classify and mark before encryption or use supported trusted tunnel metadata and policy-based identification at appropriate endpoints”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is an organization classifies applications by payload signatures inside IPsec tunnels and then finds all encrypted business traffic mapped to a single generic class; this alternative would address the wrong dependency.

That change concerns video traffic burst and jitter buffer design, where Average throughput can hide instantaneous bursts and delay variation that disrupt real-time media even when link utilization seems moderate. The reported issue instead stems from: DSCP semantics and provider class-of-service mappings are not necessarily preserved across an independent administrative domain.

That change concerns call admission and voice capacity, where Priority queuing alone cannot create bandwidth beyond circuit capacity, and too many concurrent sessions can oversubscribe voice allocation. In this question the necessary remedy is “Negotiate and implement DSCP-to-provider-CoS mapping and verify marking at each trust boundary”, 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 branch marks a critical application with DSCP 46, but the MPLS provider maps it into ordinary treatment because service-class translation was never agreed; this mechanism addresses another problem.

A /15 covers two consecutive aligned /16 networks and the selected /15 omits 10.66.0.0/16 while including unintended space. “Create aligned aggregates that cover actual component prefixes and validate binary prefix boundaries and the destination routing behavior” would remedy that alternative situation, but it would not correct the present issue: an IPv4 /27 ordinarily has only thirty usable host addresses, so it cannot accommodate the stated phones and gateway.

“Choose a phased renumbering design or carefully scoped NAT between the overlapping domains with clear DNS and application dependencies” is the supported response when overlapping address spaces are ambiguous to ordinary destination-based routing and require unique addressing or deliberate translation boundaries. Here the decisive response is “Allocate a suitably sized /25 or larger subnet after accounting for network, broadcast, gateway and expected device growth”, 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. “Reserve contiguous region-sized address blocks, allocate branch VLSM prefixes inside each block and summarize only reachable ranges at distribution boundaries” applies to that other condition. The reported evidence is a campus plans an ordinary IPv4 /27 for a voice VLAN with seventy active phones and expects enough usable addresses after adding a default gateway; this alternative would address the wrong dependency.

Unnecessary specific-route propagation increases state and change sensitivity without providing required central policy detail. “Require prefix allocation consistency before EIGRP summarization is enabled in production” would remedy that alternative situation, but it would not correct the present issue: unrestricted BGP export policy exposes destinations not authorized for upstream announcement and risks routing leaks.

“Capacity-plan BFD session counts and monitor instability before enabling aggressive timers across large deployments” is the supported response when layer 1 carrier state may not reveal a downstream path failure and slow neighbor detection extends blackhole time. Here the decisive response is “Perform automated prefix allowlist tests and route-leak simulations before modifying BGP transit peers”, so that different intervention does not meet the stated requirement.

Default broadcast OSPF network behavior can elect designated routers even when the topology is only a two-router link. “Document OSPF network-type assumptions and test peer compatibility during link-provider migrations” applies to that other condition. The reported evidence is a branch BGP edge learns a public provider default plus private corporate specifics and accidentally advertises internal /24s back to the provider; this alternative would address the wrong dependency.

MST region membership requires consistent region identifier, revision and VLAN mapping rather than matching only some VLAN names. “Version MST configuration centrally and test cross-building changes before enabling additional VLANs” would remedy that alternative situation, but it would not correct the present issue: superior BPDUs on an untrusted downstream link can alter STP root selection unless the boundary is protected.

“Inspect fiber and BPDU loss diagnostics during campus convergence design reviews” is the supported response when a non-designated STP port losing expected control messages can create a loop if it incorrectly assumes the superior path vanished. Here the decisive response is “Separate trusted infrastructure trunk roles from untrusted tenant-facing links in STP templates”, 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. “Include VLAN-count forecasts in campus Layer 2 architecture capacity planning” applies to that other condition. The reported evidence is an access switch connected to a third-party tenant device begins sending superior BPDUs and causes the building's STP root to move into the tenant network; this alternative would address the wrong dependency.

Superior BPDUs on an untrusted downstream link can alter STP root selection unless the boundary is protected. “Enable Root Guard on appropriate downstream designated ports and keep intended root roles explicit” would remedy that alternative situation, but it would not correct the present issue: ordinary underlay reachability does not assign endpoint onboarding and VXLAN edge functions to a nonfabric access device.

“Design overlay forwarding paths with validated VXLAN reachability, fabric edge encapsulation and proper transport MTU” is the supported response when a fabric control plane supplies locator information, while the data plane uses supported VXLAN encapsulation to carry endpoint traffic. Here the decisive response is “Provision eligible access devices as supported fabric edge nodes and verify host onboarding and virtual network assignments”, so that different intervention does not meet the stated requirement.

Fabric overlay endpoints require a suitable border function to exchange external route reachability with nonfabric networks. “Select appropriate fabric border nodes and external routing policy matching the site's transit and segmentation needs” applies to that other condition. The reported evidence is a newly connected access switch is routed to the fabric core but attached endpoints never receive the expected overlay segmentation because the device is not operating as a fabric edge; this alternative would address the wrong dependency.

Ordinary underlay reachability does not assign endpoint onboarding and VXLAN edge functions to a nonfabric access device. “Provision eligible access devices as supported fabric edge nodes and verify host onboarding and virtual network assignments” would remedy that alternative situation, but it would not correct the present issue: fabric overlay encapsulation adds overhead beyond ordinary IP reachability and depends on a healthy L3 underlay.

“Select appropriate fabric border nodes and external routing policy matching the site's transit and segmentation needs” is the supported response when fabric overlay endpoints require a suitable border function to exchange external route reachability with nonfabric networks. Here the decisive response is “Provide resilient IP underlay reachability and adequate end-to-end MTU for supported fabric encapsulation”, 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 new SD-Access fabric edge can reach control nodes by IP but VXLAN user traffic fails because the routed underlay path has insufficient MTU; this alternative would address the wrong dependency.