Cisco 300-420 Bundle

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. The reported issue instead stems from: MST region membership requires consistent region identifier, revision and VLAN mapping rather than matching only some VLAN names.

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. In this question the necessary remedy is “Align approved MST region configuration and verify boundary ports and per-instance root placement”, which this alternative does not provide.

That change concerns stp loop guard unidirectional failure, where A non-designated STP port losing expected control messages can create a loop if it incorrectly assumes the superior path vanished. The observed condition 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 mechanism addresses another problem.

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. The reported issue instead stems from: Without explicit multicast boundary control, group advertisements or forwarding may extend beyond authorized trust domains.

That change concerns multicast scaling versus replicated unicast, where Naive replicated unicast can consume far more shared-link capacity than a suitable multicast tree for many receivers. In this question the necessary remedy is “Apply supported multicast group or source boundary filtering at the appropriate WAN and tenant interfaces”, which this alternative does not provide.

That change concerns multicast source rpf under ecmp, where Multicast RPF decisions can be sensitive to unicast path selection, including ECMP and asymmetric routing behavior. The observed condition is a company distributes executive multicast video to finance buildings, but the design allows the group to cross into an outsourced guest network; this mechanism addresses another problem.

That change concerns dmvpn nhrp registration reachability, where Dynamic spoke resolution needs correct NHRP network ID, authentication, hub mapping and reachable tunnel source rather than only a live Internet connection. The reported issue instead stems from: An encrypted Internet overlay does not provide the same private carrier connectivity, SLA and traffic-engineering options as a qualified dedicated cloud circuit.

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. In this question the necessary remedy is “Compare direct cloud private interconnect with managed Internet VPN based on security, bandwidth, route exchange and service commitments”, which this alternative does not provide.

That change concerns dmvpn spoke to spoke optimization, where A purely hub-and-spoke forwarding policy can add latency and load when the DMVPN design is intended to allow direct spoke shortcuts. The observed condition is a regulated enterprise runs latency-sensitive cloud workloads but routes all traffic through a public Internet VPN and needs predictable private provider connectivity; this mechanism addresses another problem.

OSPF hierarchical inter-area connectivity depends on a stable backbone design and resilient area border connectivity. “Design redundant ABRs with valid backbone area connectivity and deterministic cost preferences for inter-area paths” would remedy that alternative situation, but it would not correct the present issue: a totally stubby or regular stub area cannot originate external LSAs through an internal ASBR in the required manner.

“Select E1 or E2 route treatment to reflect the required exit preference, testing both external and internal metrics” is the supported response when external Type 2 cost behavior does not account for internal cost in the same way as Type 1 when external metrics differ. Here the decisive response is “Design a supported NSSA with correct Type 7 origination and ABR translation handling where needed”, so that different intervention does not meet the stated requirement.

A fragmented area-address plan and missing ABR inter-area summarization cause avoidable detailed LSAs to propagate. “Allocate summarizable ranges and apply appropriate ABR area range configuration with complete component-route validation” applies to that other condition. The reported evidence is a remote OSPF branch must inject routes from a local non-OSPF process while still limiting external flooding from the rest of the enterprise; this alternative would address the wrong dependency.

On-change subscriptions report eligible state changes, not necessarily uniformly spaced observations required for some time-series analytics. “Document analytics cadence requirements before selecting telemetry subscription mode” would remedy that alternative situation, but it would not correct the present issue: NETCONF can expose candidate datastores, locking and commit operations where supported, unlike assuming every management interface has equivalent transactions.

“Version model support matrices and review schema revisions before monitoring-platform upgrades” 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 “Document datastore capabilities and session failure recovery before using transactional network automation”, so that different intervention does not meet the stated requirement.

Standardized models do not necessarily represent every vendor-specific operational or configuration feature. “Keep proprietary model use isolated and documented so future portability work remains manageable” applies to that other condition. The reported evidence is a network orchestrator must stage and validate multiple changes before activation but uses isolated individual REST calls with no candidate configuration review; this alternative would address the wrong dependency.

A fragmented area-address plan and missing ABR inter-area summarization cause avoidable detailed LSAs to propagate. “Keep OSPF area allocation aligned with IPAM aggregation boundaries across expansion projects” would remedy that alternative situation, but it would not correct the present issue: IPv4-only security rules do not automatically enforce the same trust boundary for IPv6 traffic on a dual-stack path.

“Document address-translation limitations for literal IPv4 references and validate DNS64 behavior during migrations” is the supported response when IPv6-only clients cannot communicate with IPv4-only services without supported translation and suitable destination synthesis. Here the decisive response is “Include IPv6 policy and telemetry reviews in every dual-stack readiness audit”, so that different intervention does not meet the stated requirement.

Overlay headers reduce usable path MTU and blocked ICMPv6 Packet Too Big feedback can prevent Path MTU Discovery. “Include tunnel and encryption overhead in WAN design capacity and test plans” applies to that other condition. The reported evidence is a security design filters outbound IPv4 branch traffic but turns on IPv6 at WAN gateways without corresponding IPv6 ACLs and telemetry; this alternative would address the wrong dependency.

A high-speed physical port does not imply equal committed service rate, so uncontrolled bursts can be discarded in the provider network. “Revalidate shaping rates against provider CIR and accounting overhead after circuit or device changes” would remedy that alternative situation, but it would not correct the present issue: ASM initially uses a shared RP tree and may switch to source-specific shortest-path forwarding according to design and platform behavior.

“Record PIM DR priorities and test host join continuity after an access router outage” is the supported response when PIM DR election provides a defined designated router role on a multiaccess segment to avoid conflicting join responsibilities. Here the decisive response is “Test multicast forwarding path changes and source-tree utilization for large streaming applications”, so that different intervention does not meet the stated requirement.

Source-specific multicast applications need supported source-aware receiver membership signaling, commonly IGMPv3 for IPv4. “Verify switch snooping and receiver protocol versions before enabling SSM at scale” applies to that other condition. The reported evidence is a PIM sparse-mode ASM network sends high-rate streaming traffic through the rendezvous point even after receivers could reach a more efficient source tree; this alternative would address the wrong dependency.

NETCONF and RESTCONF share model-driven concepts but use different protocol transports, operation semantics and session behavior. “Match API protocol to the orchestrator requirements and supported device capabilities, including SSH/XML NETCONF or HTTP/RESTCONF workflows” would remedy that alternative situation, but it would not correct the present issue: repeated broad request-response polling can impose higher overhead than selective model-driven subscription updates for suitable telemetry.

“Use supported RESTCONF PATCH, PUT or POST methods at correct YANG resource paths with authorization and content types” is the supported response when RESTCONF uses resource-oriented HTTP methods with defined read and write semantics, so GET is not an appropriate configuration write operation. Here the decisive response is “Use platform-supported model-driven telemetry subscriptions for required state paths with sensible reporting intervals and collector capacity”, so that different intervention does not meet the stated requirement.

Coarse periodic publication can delay visibility of short state transitions and is not equivalent to supported event-driven on-change reporting. “Use supported on-change telemetry for the neighbor state path with safeguards for subscriber load and update volume” applies to that other condition. The reported evidence is a WAN operations team polls thousands of interface counters through legacy SNMP every few seconds and saturates device management CPU during incidents; this alternative would address the wrong dependency.

An oversized or unbounded strict-priority queue can consume interface capacity and deny adequate service to other classes. “Reserve low-latency priority treatment for justified real-time traffic with controlled bandwidth and balanced class allocations” would remedy that alternative situation, but it would not correct the present issue: PIM DR election provides a defined designated router role on a multiaccess segment to avoid conflicting join responsibilities.

“Evaluate bidirectional PIM or another supported distribution method against source count, RP and security requirements” is the supported response when a dense many-to-many application can impose excessive source tree state if its delivery model ignores suitable shared bidirectional multicast designs. Here the decisive response is “Design suitable PIM interface priorities and neighbor reachability for predictable designated-router selection”, so that different intervention does not meet the stated requirement.

Independent rendezvous points do not automatically exchange all active-source information across ASM multicast domains. “Use supported MSDP or a suitable alternative interdomain multicast design with appropriate RP and source policies” applies to that other condition. The reported evidence is a shared LAN has two PIM routers and a new receiver joins, but both routers attempt to act as the first-hop join forwarder for the segment; this alternative would address the wrong dependency.

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” would remedy that alternative situation, but it would not correct the present issue: dynamic spoke resolution needs correct NHRP network ID, authentication, hub mapping and reachable tunnel source rather than only a live Internet connection.

“Separate tunnel encapsulation requirements from cryptographic protection during design reviews” is the supported response when GRE provides encapsulation for multiple protocols but does not itself encrypt or authenticate payload confidentiality. Here the decisive response is “Check dynamic public IP and NAT dependencies during DMVPN branch modem replacements”, so that different intervention does not meet the stated requirement.

Logical dual-circuit contracts may share a physical access path and suffer a common-cause outage. “Request physical route-diversity evidence and test failover rather than counting only interface numbers” applies to that other condition. The reported evidence is after replacing a branch Internet router, its DMVPN tunnel interface can reach the public network but the spoke no longer appears as registered at the hub; this alternative would address the wrong dependency.

Traditional active-standby first-hop redundancy does not by itself provide the desired per-client gateway load distribution. “Consider GLBP where supported or a different routed access and anycast design, based on platform capability and operational needs” would remedy that alternative situation, but it would not correct the present issue: a single physical gateway address makes host access depend on one distribution device even when a second gateway exists.

“Track the required upstream path and decrement priority enough for a healthy standby gateway to assume forwarding” is the supported response when FHRP presence alone may not account for upstream path viability without appropriate object or interface tracking. Here the decisive response is “Design a supported FHRP virtual gateway with aligned priorities, Layer 2 reachability and safe failover between distribution switches”, so that different intervention does not meet the stated requirement.

FHRP peers must exchange control messages in a correctly shared VLAN to maintain a single active forwarding role. “Restore approved VLAN trunk reachability and compatible HSRP group and timer settings across both devices” applies to that other condition. The reported evidence is a campus user VLAN has two distribution switches, but its hosts use the physical IP of only one switch as the default gateway and lose external connectivity during maintenance; this alternative would address the wrong dependency.