Cisco 300-420 Bundle

That change concerns eigrp route summarization at hub, where Unnecessary specific-route propagation increases state and change sensitivity without providing required central policy detail. The reported issue instead stems from: OSPF hierarchical inter-area connectivity depends on a stable backbone design and resilient area border connectivity.

That change concerns ospf area range summarization, where A fragmented area-address plan and missing ABR inter-area summarization cause avoidable detailed LSAs to propagate. In this question the necessary remedy is “Design redundant ABRs with valid backbone area connectivity and deterministic cost preferences for inter-area paths”, which this alternative does not provide.

That change concerns ospf nssa external redistribution, where A totally stubby or regular stub area cannot originate external LSAs through an internal ASBR in the required manner. The observed condition is an enterprise creates several OSPF nonbackbone areas linked through a single fragile ABR with no alternate route into area zero; this mechanism addresses another problem.

That change concerns eigrp stub branch query containment, where Unbounded EIGRP query scope and nontransit spokes can prolong active route computation across a large topology. The reported issue instead stems from: An unprotected adjacency trust boundary can admit unauthorized IS-IS control messages into a routing domain.

That change concerns is-is dual-stack address-family strategy, where Protocol adjacency and IPv4 routes do not alone establish correct IPv6 reachability, interface addressing or address-family support. In this question the necessary remedy is “Deploy supported IS-IS authentication with coordinated algorithms and keys and restrict peers to intended segments”, which this alternative does not provide.

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 observed condition is routing peers on a shared provider Ethernet segment accept IS-IS adjacencies without authentication, allowing an unintended device to affect topology calculations; this mechanism addresses another problem.

Dynamic spoke resolution needs correct NHRP network ID, authentication, hub mapping and reachable tunnel source rather than only a live Internet connection. “Check dynamic public IP and NAT dependencies during DMVPN branch modem replacements” would remedy that alternative situation, but it would not correct the present issue: a purely hub-and-spoke forwarding policy can add latency and load when the DMVPN design is intended to allow direct spoke shortcuts.

“Request physical route-diversity evidence and test failover rather than counting only interface numbers” is the supported response when logical dual-circuit contracts may share a physical access path and suffer a common-cause outage. Here the decisive response is “Validate dynamic tunnel establishment and hub policy under branch renumbering and failover”, so that different intervention does not meet the stated requirement.

An encrypted Internet overlay does not provide the same private carrier connectivity, SLA and traffic-engineering options as a qualified dedicated cloud circuit. “Document cloud provider port limits, routing policies and redundancy across independent interconnect facilities” applies to that other condition. The reported evidence 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 alternative would address the wrong dependency.

Gateway role restoration depends on the selected FHRP protocol and its configured preemption settings, not priority numbers alone. “Document whether automatic takeover or stability-first non-preemption is intended for each critical VLAN” would remedy that alternative situation, but it would not correct the present issue: FHRP peers must exchange control messages in a correctly shared VLAN to maintain a single active forwarding role.

“Validate gateway priority changes against real upstream failures rather than only powering off the active switch” 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 “Audit VLAN membership and FHRP peer reachability before modifying router priority values”, so that different intervention does not meet the stated requirement.

A single physical gateway address makes host access depend on one distribution device even when a second gateway exists. “Include virtual-gateway ownership and split-brain validation in every campus distribution switch change window” applies to that other condition. The reported evidence is two redundant distribution switches both believe they are HSRP active after a VLAN trunk blocks hello messages, causing inconsistent gateway ARP responses; this alternative would address the wrong dependency.

BGP additional paths must satisfy supported multipath eligibility rules and configured maximum-path policy to share traffic. “Evaluate path attributes and supported multipath settings, then choose a design that preserves deterministic failover” would remedy that alternative situation, but it would not correct the present issue: IPv6-only clients cannot communicate with IPv4-only services without supported translation and suitable destination synthesis.

“Select native dual stack for capable segments and reserve translation for real IPv4-only boundaries with documented requirements” 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 “Design appropriate NAT64 plus DNS64 service boundaries, DNS behavior and application compatibility exceptions”, 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. “Budget tunnel overhead in MTU planning, preserve required ICMPv6 control messages and validate endpoints' segment sizes” applies to that other condition. The reported evidence is a company deploys IPv6-only client VLANs that must reach legacy IPv4-only APIs, but assumes routing IPv6 packets directly to IPv4 server addresses is possible; this alternative would address the wrong dependency.

Internal OSPF cost does not communicate an intended interconnect preference to the neighboring autonomous system. “Validate BGP policy precedence and provider rules instead of assuming MED overrides every upstream preference” would remedy that alternative situation, but it would not correct the present issue: AS-path prepending mainly affects remote path selection; outbound path preference within the local AS is commonly controlled with local preference.

“Verify both BGP control-plane route presence and IGP next-hop resolution in every edge design” is the supported response when IBGP typically preserves the external next hop, which must be reachable through the internal routing infrastructure. Here the decisive response is “Separate inbound and outbound traffic-engineering objectives in BGP policy design documentation”, so that different intervention does not meet the stated requirement.

Conventional iBGP full mesh grows quadratically and becomes costly to configure, observe and recover. “Test reflection path diversity and redundant reflector failure modes before retiring full-mesh peers” applies to that other condition. The reported evidence is a dual-homed enterprise wants all internal sites to prefer the primary provider for outbound traffic but adjusts AS-path prepending on inbound advertisements instead; this alternative would address the wrong dependency.

The orchestration function helps WAN edges discover and authenticate to the fabric but should not be placed in the regular data forwarding path. “Test zero-touch onboarding trust and regional orchestrator availability before scaling the fabric” would remedy that alternative situation, but it would not correct the present issue: multihoming and address translation must account for both directions; outbound route changes alone may not preserve return paths.

“Review transport and security policy together whenever adding a new Internet link” is the supported response when a hybrid WAN needs explicit route and security decisions because reachability alone does not guarantee sensitive traffic uses approved paths. Here the decisive response is “Test full transactions and reverse paths, not only traceroutes leaving the branch WAN edge”, 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 an enterprise tests its secondary Internet link and sees outbound connectivity, but return traffic continues toward a withdrawn primary public prefix; this alternative would address the wrong dependency.

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” would remedy that alternative situation, but it would not correct the present issue: data-plane tunnel presence does not guarantee that control-plane route advertisement and segmentation policy deliver needed service prefixes.

“Map TLOCs to genuinely diverse approved transport interfaces and validate policy-based failover” is the supported response when logical transport labels or TLOCs do not inherently represent independent circuits, carrier facilities or last-mile paths. Here the decisive response is “Validate OMP route advertisements and centralized policy across controllers with intended VPN and TLOC eligibility”, so that different intervention does not meet the stated requirement.

Secure SD-WAN fabric admission requires authorized organization identifiers and valid identity trust, not just IP routing. “Design approved CA trust, certificate lifecycle and device authorization procedures for every control node and edge” applies to that other condition. The reported evidence is a new branch has functioning encrypted transport tunnels but receives no remote service routes because centralized SD-WAN control policies omit the site; this alternative would address the wrong dependency.

That change concerns is-is overload-bit during maintenance, where Premature use of a partially ready intermediate system can blackhole transit despite apparently formed control-plane neighbors. The reported issue instead stems from: Network dual stacking alone does not add AAAA DNS records, IPv6 listening services, security policy or path validation to existing applications.

That change concerns ipv6 subnet prefix length on end-user lan, where Typical Ethernet SLAAC uses /64 interface identifiers and ordinary host autoconfiguration expectations are not met by arbitrary longer access prefixes. In this question the necessary remedy is “Plan application-by-application dual-stack readiness including DNS, access controls, routing, management and rollback verification”, which this alternative does not provide.

That change concerns is-is level 1 and level 2 area topology, where IS-IS Level 1 operates within an area while Level 2 provides inter-area connectivity and should bound unwanted topology flooding. The observed condition is a company turns on IPv6 routing at its branch WAN edge but assumes every application automatically supports IPv6 even though several server DNS records and firewall policies remain IPv4-only; this mechanism addresses another problem.

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: without class-based queue service, different traffic priorities may compete equally under congestion rather than receiving guaranteed minimum allocations.

“Classify and mark before encryption or use supported trusted tunnel metadata and policy-based identification at appropriate endpoints” is the supported response when encryption hides much application payload from intermediate classifiers, so deep packet inspection may not see per-app content inside the tunnel. Here the decisive response is “Implement appropriate CBWFQ or platform-supported scheduler weights after classifying actual traffic”, so that different intervention does not meet the stated requirement.

DSCP semantics and provider class-of-service mappings are not necessarily preserved across an independent administrative domain. “Negotiate and implement DSCP-to-provider-CoS mapping and verify marking at each trust boundary” applies to that other condition. The reported evidence is a WAN link has three business traffic classes but the design uses only a best-effort FIFO queue, creating unpredictable delay during peaks; this alternative would address the wrong dependency.

Extending Layer 2 broadly across campus buildings increases loop, convergence and failure-domain exposure. “Set explicit maximum Layer 2 failure domains during new-building network approvals” would remedy that alternative situation, but it would not correct the present issue: ordinary directed and local broadcasts do not automatically cross routed boundaries, so an explicit authorized delivery design is required.

“Align MAC limit exceptions with phones, hypervisors and other genuine multi-MAC endpoints” is the supported response when without port security or identity-aware access control, a simple access port may learn multiple endpoint MAC addresses without limitation. Here the decisive response is “Document WoL security and relay dependencies when redesigning campus routing and NAC controls”, 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 an enterprise wants remote Wake-on-LAN for sleeping workstations in many VLANs but the management tool sends only local Ethernet magic packets from a central server; this alternative would address the wrong dependency.