Free Practice Questions for Cisco 300-640 Exam

In Cisco Nexus Dashboard, a correlated anomaly is a secondary condition that Nexus Dashboard has associated through cause-and-effect analysis with another anomaly identified as the probable root cause. Cisco's current documentation explicitly distinguishes root-cause anomalies from correlated anomalies: the root anomaly triggers additional symptoms, and those dependent symptoms are displayed as correlated events.

For example, a physical or routing event may cause a downstream BGP session to fail. Rather than presenting each symptom as an independent failure, Nexus Dashboard analyzes relationships involving interfaces, devices, protocols, and timestamps. The BGP peer-down condition can therefore appear as correlated when a higher-level underlying anomaly explains it.

Option A incorrectly associates correlation with user-account activity. Option B describes repetition across several devices, which is not what the correlation indicator means. Option D refers generally to impact analysis rather than the specific root-cause relationship communicated by the label.

This feature reduces troubleshooting time because engineers can focus first on the root anomaly. Cisco specifically notes that resolving the underlying root cause should also resolve the anomalies correlated with that condition.

Study Guide Reference: AI Infrastructure Operations and Troubleshooting — Nexus Dashboard assurance, anomaly correlation, root-cause identification, and troubleshooting.

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The organization already owns third-party AI servers and NVMe storage, so it requires a network-centric AI fabric rather than a Cisco full-stack solution that bundles UCS compute. Cisco Nexus Hyperfabric supports bring-your-own infrastructure scenarios while providing cloud-based design, deployment, management, telemetry, and lifecycle operations.

The licensing distinction is critical. Cisco's current Nexus Hyperfabric documentation defines Essentials primarily for general-purpose fabrics, whereas Premier is the entitlement tier designed for AI fabrics. Premier includes AI-specific functionality such as alignment with NVIDIA reference architectures, adaptive routing support, AI-validated blueprints, automated lossless backend networking, and monitoring between switches and servers.

Option A uses the correct bring-your-own model but the wrong subscription tier for an AI fabric. Option D represents the full-stack Hyperfabric AI model, which includes Cisco UCS servers and therefore conflicts with the requirement to retain existing third-party compute. Option C does not match the requested Cisco 6000 Series cloud-managed Hyperfabric architecture.

Accordingly, BYO AI Hyperfabric using Cisco 6000 Series switches with the Premier entitlement satisfies both reuse of existing infrastructure and AI-specific cloud-managed networking.

Study Guide Reference: 3.3.c Hyperfabric — deploy AI-ready fabrics using Cisco orchestration tools.

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VAST Data Universal Storage is the architecture explicitly associated with these requirements. Cisco's AI Data Platform documentation describes VAST's Disaggregated Shared-Everything (DASE) architecture, which separates stateless compute from persistent flash capacity so that storage performance and capacity can scale independently. This architecture is designed to eliminate conventional storage-controller bottlenecks and support extremely large AI datasets.

Cisco's AI POD with VAST architecture integrates Cisco UCS infrastructure, Cisco Intersight lifecycle management, high-performance Ethernet/RDMA networking, and VAST's all-flash storage platform. Cisco documentation also identifies UCS C225 M8 systems within VAST-based storage designs and describes the solution as optimized for high-throughput AI workloads.

GPU Direct Storage is particularly important because it reduces unnecessary CPU involvement and intermediate data copies when transferring datasets between storage and GPU memory. Combined with RDMA, this architecture can sustain the high parallel bandwidth required by large training and fine-tuning environments.

NetApp AFF and Pure Storage FlashBlade are capable enterprise storage products, but the DASE terminology uniquely identifies VAST. Local NVMe cannot provide the required exabyte-scale shared-storage architecture and would fragment datasets across individual GPU servers.

Study Guide Reference: AI Infrastructure Components and Architecture — high-performance storage, AI PODs, RDMA, scale, and shared AI data platforms.

The intended solution is Cisco Nexus Hyperfabric AI because it provides an integrated on-premises AI infrastructure managed through a cloud-hosted controller. Cisco's current reference architecture documents a configuration using 12 Cisco UCS C885A M8 servers with eight NVIDIA GPUs each, producing a 96-GPU cluster . The architecture uses Cisco Hyperfabric switching and is engineered for high-performance AI training and inference.

Cisco also states that the full-stack Hyperfabric AI infrastructure is aligned with NVIDIA Enterprise Reference Architecture requirements and uses a cloud controller to manage network design, deployment, monitoring, upgrades, troubleshooting, and scaling.

This eliminates option C because Nexus Dashboard is not the cloud-managed Hyperfabric full-stack architecture described. Option D incorrectly characterizes Intersight as the AI network-fabric controller; Intersight manages UCS infrastructure, whereas Nexus Hyperfabric provides the required cloud-managed network lifecycle.

The uploaded question specifically maps the 96-GPU requirement to the Small AI Cluster , and its source answer is A. Current Cisco public documentation confirms the 96-GPU Hyperfabric topology and cloud-managed NVIDIA-aligned architecture, although current product material presents scalable cluster templates more generally as small through extra-large.

Study Guide Reference: 3.3.c Hyperfabric; 2.1 network scalability; 2.2 GPU compute scalability.

Ethernet Network Control Policy

Ethernet Network Group Policy

Ethernet QoS Policy

Ethernet Adapter Policy

The mappings correspond to the functional boundaries of Cisco Intersight vNIC policies. Ethernet Network Control Policy manages link-layer behavior including CDP and LLDP. Cisco's Intersight documentation explicitly identifies CDP, LLDP transmit/receive, MAC registration, and uplink-failure behavior as Network Control settings.

Ethernet Network Group Policy controls VLAN membership for FI-attached servers, including the set of allowed VLANs and the optional native VLAN. Ethernet QoS Policy supplies performance-oriented vNIC characteristics such as MTU, rate limiting, traffic priority, CoS, and burst parameters. Cisco's current RoCE configuration guide lists MTU and rate-limit values directly under Ethernet QoS configuration.

Finally, Ethernet Adapter Policy contains adapter-level behavior and performance parameters, including RoCE configuration used for high-performance RDMA interfaces.

Ethernet Network Policy is the unused choice. Cisco documents that policy primarily for VLAN configuration on standalone servers, whereas Ethernet Network Group Policy is the relevant VLAN policy for Fabric Interconnect-attached UCS X-Series vNICs.

Study Guide Reference: AI Infrastructure Deployment and Data Management — UCS vNIC templates, Ethernet policies, QoS, VLAN configuration, and RoCE.

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ECN (Explicit Congestion Notification)

PFC (Priority Flow Control)

ECN and PFC address different congestion conditions in a RoCEv2 fabric and are intended to complement rather than replace each other. ECN is the appropriate mechanism for fabric-level congestion generated by incast patterns. When several GPU or storage senders simultaneously transmit toward the same destination, switch queues begin to build. ECN-capable switches mark packets rather than immediately dropping them, allowing the receiving endpoint to generate congestion feedback so the transmitting source can reduce its sending rate.

PFC provides hop-by-hop loss prevention for the designated lossless Ethernet priority. When an endpoint or downstream interface cannot accept a burst quickly enough and a queue approaches its configured threshold, PFC transmits pause frames for that specific priority. This temporarily stops upstream transmission and prevents packet loss.

Cisco's RoCEv2 designs combine ECN and PFC precisely because ECN provides proactive end-to-end congestion management while PFC acts as the protective mechanism when queue buildup becomes severe or occurs faster than endpoint rate adaptation can respond.

WRED can provide the queue-marking mechanism associated with ECN, but the requested logical congestion-control mechanism is ECN. AFD is not the corresponding RoCEv2 lossless mechanism for either description.

Study Guide Reference: AI Infrastructure Deployment and Data Management — congestion control, RoCEv2, ECN, PFC, QoS, and lossless Ethernet.

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GPU Utilization and GPU Performance are the two choices that directly measure the behavior of accelerator resources used by AI workloads. GPU utilization indicates how actively the accelerator's computational resources are being consumed. Persistent low utilization can expose CPU, storage, networking, synchronization, or workload-scheduling bottlenecks, while sustained high utilization generally indicates effective use of expensive GPU capacity.

Cisco Intersight is increasingly oriented toward AI-specific infrastructure visibility. Cisco states that Intersight provides actionable metrics for GPU performance , resource-utilization trends, and power efficiency. Its Metrics Explorer and monitoring capabilities provide deep telemetry for infrastructure resources, including AI accelerators.

Explorer and Monitor in options B and C represent interfaces or functional capabilities rather than the performance metrics requested by the question. System CPU Utilization is useful when determining whether a workload is host-CPU constrained, but it does not directly measure GPU performance or GPU utilization.

Accordingly, A and D are the two choices that correspond most directly to the stated objective of measuring GPU performance and utilization.

Study Guide Reference: AI Infrastructure Operations and Troubleshooting — monitoring GPU performance, utilization, resource bottlenecks, and Cisco Intersight telemetry.

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A rail-optimized architecture is intentionally designed so that communication among corresponding GPU ranks within a single scalable unit can remain on the rail or leaf switches. This provides single-hop forwarding and avoids unnecessary traversal through spine switches, reducing latency for collective communication.

Spines become necessary when the deployment expands beyond one scalable unit. Cisco explicitly documents that multiple scalable units can be interconnected through leaf-and-spine switching. Traffic among GPUs inside one scalable unit benefits from rail-optimized single-hop communication, whereas traffic between GPUs located in different scalable units traverses the spine layer.

Therefore, option C precisely describes when spine switches provide architectural value: scaling the AI fabric beyond the boundaries of one scalable unit .

Option A is inaccurate because the rail design already provides the required local GPU bandwidth within the scalable unit; adding spines is not primarily intended to increase local rail bandwidth. Option B mischaracterizes the principal design purpose. Although additional topology can contribute to resiliency, spines are introduced fundamentally for interconnecting scalable units and enabling scale-out. Option D is also incorrect because increased buffering is not the architectural reason for introducing a spine tier.

Study Guide Reference: AI Infrastructure Components and Architecture — rail-optimized topology, scalable units, nonblocking network design, latency, and horizontal scaling.

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