300-420 Reviews Questions

Cisco SD-Access uses virtual networks as macro-segmentation boundaries, and those VNs are represented as VRF instances in the fabric. By design, separate VNs do not communicate directly inside the overlay unless the design introduces controlled inter-VN routing. Cisco SD-Access designs commonly use an external fusion router, firewall, or shared-services device to map fabric VNs to external VRFs and selectively exchange routes between them. That is the correct design because it preserves segmentation while allowing policy-controlled access to shared resources or selected networks. GRE tunnels between fabric edges are not the normal SD-Access inter-VN communication method and would bypass the intended fabric policy model. Security Group Tags provide microsegmentation within or across policy domains, but SGTs do not by themselves leak routes between separate virtual networks. Route leaking on fabric border nodes is not the recommended standalone answer here because inter-VN communication is normally provided through a fusion device or firewall outside the fabric. Therefore, the correct solution is external fusion routing with controlled VRF route exchange.

For model-driven telemetry with periodic updates, the architect must understand that each periodic update sends the subscribed data at the configured interval. Cisco telemetry guidance distinguishes periodic subscriptions from on-change subscriptions. A periodic subscription streams a full copy of the subscribed data element or table at each interval, even if the underlying state has not changed. That behavior is useful when the collector needs regular time-series samples, trending, or baseline monitoring, but it creates predictable bandwidth and collector-load requirements. On-change subscriptions are different: they publish updates when the subscribed state changes and are more efficient for state changes such as interface status, memory thresholds, or protocol adjacency m ovement. Empty subscription behavior and initial update timing may matter in specific implementations, but they are not the main design consideration in this question. Since the customer requires periodic updates, the design must size the transport, collector, retention system, and subscription intervals around repeated full data delivery. Reference topics: model-driven telemetry, periodic subscription, on-change subscription, YANG-modeled operational data, collector sizing.

The primary capability of IaaS in this question is elastic scaling: the ability to increase or decrease infrastructure resources based on demand. In Infrastructure as a Service, the provider offers compute, storage, and network resources as an on-demand service, while the customer deploys operating systems and applications on top of that infrastructure. Cisco cloud material describes this model as providing scalable IT capacity without requiring the organization to own all physical assets. Option C is the best answer because dynamic capacity adjustment is a fundamental cloud capability and a major reason enterprises choose IaaS for variable workloads. Option B is a valid business benefit because consumption-based billing can reduce cost, but the question asks for a primary capability, not the pricing model. Option D describes automation and orchestration, which support cloud operations but are not the specific capability being tested. Option A is closer to hybrid-cloud workload mobility and is not guaranteed by IaaS alone. Reference topics: cloud service models, IaaS, elasticity, scalable compute, on-demand resource provisioning.

Secure segmentation is the Cisco SD-WAN Secure Direct Cloud Access function that separates user traffic into different zones and VPNs or VRFs. In Cisco SD-WAN, VPNs provide logical segmentation that is comparable to VRF separation in traditional routing. Secure Direct Cloud Access extends this segmentation model when users access internet and cloud applications directly from the branch. The design can keep corporate, guest, payment, voice, IoT, and other traffic classes isolated, with policy and security controls applied per segment or zone. Centralized data policy controls forwarding behavior, but the feature that divides traffic into separate zones and VPN or VRF contexts is secure segmentation. Perimeter control and application-aware routing are useful security and performance functions, but they do not describe the core segmentation mechanism. Segmentation is a fundamental SD-WAN design requirement because direct cloud access must not collapse trust boundaries simply because traffic no longer hairpins through a central data center. Reference topics: Cisco SD-WAN secure segmentation, VPNs, VRFs, direct cloud access, zone-based policy.