Cisco 300-420 Bundle

That change concerns eigrp unequal cost traffic sharing, where EIGRP unequal-cost load sharing is not enabled simply because multiple routes exist and is constrained by feasibility and variance. The reported issue instead stems from: An EIGRP feasible successor must satisfy its feasibility condition relative to the successor's feasible distance to prevent loops.

That change concerns eigrp route summarization at hub, where Unnecessary specific-route propagation increases state and change sensitivity without providing required central policy detail. In this question the necessary remedy is “Review reported and feasible distances and design valid loop-free alternatives rather than forcing an invalid candidate”, which this alternative does not provide.

That change concerns eigrp hub topology route leaking, where Uncontrolled bidirectional redistribution can reintroduce routes, create loops and lose source-of-truth route preference. The observed condition is an enterprise asks EIGRP to install an alternate path solely because the alternate advertised distance is low, without checking the feasibility condition; this mechanism addresses another problem.

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: a single physical gateway address makes host access depend on one distribution device even when a second gateway exists.

“Audit VLAN membership and FHRP peer reachability before modifying router priority values” is the supported response when FHRP peers must exchange control messages in a correctly shared VLAN to maintain a single active forwarding role. Here the decisive response is “Include virtual-gateway ownership and split-brain validation in every campus distribution switch change window”, so that different intervention does not meet the stated requirement.

Traditional active-standby first-hop redundancy does not by itself provide the desired per-client gateway load distribution. “Compare first-hop load sharing and operational complexity before selecting a protocol solely for redundancy” 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.

Coarse periodic publication can delay visibility of short state transitions and is not equivalent to supported event-driven on-change reporting. “Test event delivery under frequent flaps and avoid overwhelming collection systems with unbounded updates” would remedy that alternative situation, but it would not correct the present issue: RESTCONF uses resource-oriented HTTP methods with defined read and write semantics, so GET is not an appropriate configuration write operation.

“Run interoperability tests for protocol authentication, payload encoding and error handling before deployment” is the supported response when NETCONF and RESTCONF share model-driven concepts but use different protocol transports, operation semantics and session behavior. Here the decisive response is “Validate method, status-code and error-body handling in network API client tests”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is an automation tool sends a GET request to change a router interface description and assumes any successful HTTP response implies a configuration mutation; this alternative would address the wrong dependency.

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 reported issue instead stems from: Unrestricted BGP export policy exposes destinations not authorized for upstream announcement and risks routing leaks.

That change concerns ospf point-to-point network type, where Default broadcast OSPF network behavior can elect designated routers even when the topology is only a two-router link. In this question the necessary remedy is “Apply explicit approved outbound prefix filters at the eBGP boundary and validate maximum prefix expectations”, which this alternative does not provide.

That change concerns ospf bfd rapid failure detection, where Layer 1 carrier state may not reveal a downstream path failure and slow neighbor detection extends blackhole time. The observed condition is a branch BGP edge learns a public provider default plus private corporate specifics and accidentally advertises internal /24s back to the provider; this mechanism addresses another problem.

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: Overlapping address spaces are ambiguous to ordinary destination-based routing and require unique addressing or deliberate translation boundaries.

That change concerns ipv4 summarization boundary alignment, where A /15 covers two consecutive aligned /16 networks and the selected /15 omits 10.66.0.0/16 while including unintended space. In this question the necessary remedy is “Choose a phased renumbering design or carefully scoped NAT between the overlapping domains with clear DNS and application dependencies”, which this alternative does not provide.

That change concerns vlsm sized campus user allocation, where An IPv4 /27 ordinarily has only thirty usable host addresses, so it cannot accommodate the stated phones and gateway. The observed condition 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 mechanism addresses another problem.

That change concerns mutual redistribution loop prevention, where Bidirectional multipoint redistribution without route tagging or authoritative direction can reintroduce routes into their source protocol. The reported issue instead stems from: Extending Layer 2 broadly across campus buildings increases loop, convergence and failure-domain exposure.

That change concerns multicampus route summarization boundary, where Missing site-level address summarization increases routing state and exposes the WAN to local campus topology churn. In this question the necessary remedy is “Design routed access where supported, using local Layer 3 boundaries and deterministic IGP connectivity between buildings”, which this alternative does not provide.

That change concerns vacl segmentation inside one vlan, where An SVI routed ACL does not necessarily inspect intra-VLAN switched frames that never reach Layer 3 forwarding. The observed condition is a multicampus organization extends each access VLAN over multiple buildings to preserve gateway placement, creating a large shared spanning-tree fault domain; this mechanism addresses another problem.

A per-VLAN spanning-tree model scales protocol state with VLAN count and may become less efficient than suitable aggregated instances. “Assess MST or Layer 3 access boundaries against actual traffic steering and availability requirements” 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.

“Use Loop Guard on appropriate non-edge STP links and deploy complementary unidirectional link detection where supported” 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 “Enable Root Guard on appropriate downstream designated ports and keep intended root roles explicit”, so that different intervention does not meet the stated requirement.

Physical link-up is insufficient to guarantee bidirectional signal integrity, which can affect control-plane protocols and forwarding. “Enable appropriate UDLD modes on supported fiber links and validate shutdown and recovery procedures” 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.

Traditional point-to-point encryption tunnel meshes may add unnecessary topology and scale complexity for a trusted private routed underlay. “Treat key server redundancy, rekey windows and group membership security as critical design dependencies” would remedy that alternative situation, but it would not correct the present issue: tenant route separation blocks cross-VPN reachability until carefully controlled route-target import/export rules make the intended service available.

“Reconcile cloud subnet additions with tunnel selectors and routing changes before declaring VPN rollout complete” is the supported response when VPN session status can be healthy while mismatched crypto ACLs or traffic selectors omit the application flow. Here the decisive response is “Review route target overlaps and firewall rules together when allowing cross-VPN shared services”, so that different intervention does not meet the stated requirement.

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” applies to that other condition. The reported evidence is two enterprise departments use separate MPLS VPNs but need access to one shared CRM subnet without importing all routes from one another; this alternative would address the wrong dependency.

Uncontrolled multihoming can select unpredictable exits and cause asymmetry or suboptimal paths under provider changes. “Define local preference, inbound announcement policy and health tracking based on primary and backup business requirements” would remedy that alternative situation, but it would not correct the present issue: local interface carrier may remain up when upstream service fails, so a static route without health tracking can blackhole traffic.

“Design separate CE devices, access paths and service-provider terminations in accordance with the required availability objective” is the supported response when multiple logical VLANs on the same physical CE and provider device do not provide independent failure domains. Here the decisive response is “Use supported service probing and tracked next-hop or routing convergence to withdraw an unusable primary path”, so that different intervention does not meet the stated requirement.

Shortcut VPN topology changes can bypass required inspection if the WAN policy assumes every flow transits a central hub. “Use a security-enforcing hub design or distributed inspection architecture with explicit policy for branch-to-branch traffic” applies to that other condition. The reported evidence is a branch prefers fiber Internet over backup DSL but its static primary default route remains installed after an upstream outage beyond the local Ethernet handoff; 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. “Deploy supported BFD for the intended OSPF peers, validate timers against platform capacity and test false-positive risk” would remedy that alternative situation, but it would not correct the present issue: an unprotected adjacency trust boundary can admit unauthorized IS-IS control messages into a routing domain.

“Implement supported IS-IS IPv6 reachability with interface family configuration and consistent topology preferences” is the supported response when protocol adjacency and IPv4 routes do not alone establish correct IPv6 reachability, interface addressing or address-family support. Here the decisive response is “Deploy supported IS-IS authentication with coordinated algorithms and keys and restrict peers to intended segments”, so that different intervention does not meet the stated requirement.

Summary advertisement can attract destinations no longer reachable through the summarizing area, creating a predictable blackhole. “Advertise summaries only with valid downstream coverage or an explicitly documented safe discard and failover behavior” applies to that other condition. The reported evidence is routing peers on a shared provider Ethernet segment accept IS-IS adjacencies without authentication, allowing an unintended device to affect topology calculations; this alternative would address the wrong dependency.

FHRP peers must exchange control messages in a correctly shared VLAN to maintain a single active forwarding role. “Audit VLAN membership and FHRP peer reachability before modifying router priority values” would remedy that alternative situation, but it would not correct the present issue: gateway role restoration depends on the selected FHRP protocol and its configured preemption settings, not priority numbers alone.

“Compare first-hop load sharing and operational complexity before selecting a protocol solely for redundancy” is the supported response when traditional active-standby first-hop redundancy does not by itself provide the desired per-client gateway load distribution. Here the decisive response is “Document whether automatic takeover or stability-first non-preemption is intended for each critical VLAN”, so that different intervention does not meet the stated requirement.

FHRP presence alone may not account for upstream path viability without appropriate object or interface tracking. “Validate gateway priority changes against real upstream failures rather than only powering off the active switch” applies to that other condition. The reported evidence is after a higher-priority distribution router returns from maintenance, operations expects it to become master automatically but the chosen VRRP preemption behavior was disabled; this alternative would address the wrong dependency.