Cisco Implementing Cisco Data Center AI Infrastructure (DCAI) 300-640 Exam Dumps: Updated Questions & Answers (October 2026)

backend network

frontend network

storage network

management network

Large AI environments normally separate traffic into purpose-built fabrics because GPU collective communication, storage I/O, application access, and infrastructure management have fundamentally different performance and availability characteristics. Cisco identifies the backend network as the east-west fabric dedicated to inter-GPU communication. It carries high-bandwidth RoCEv2/RDMA traffic associated with distributed training and must provide exceptionally low latency and lossless behavior.

The frontend network provides north-south connectivity between AI nodes and the wider data center, supporting application access, inference traffic, general data movement, logging, and other in-band services. The storage network connects compute nodes to shared datasets, model checkpoints, and high-performance parallel or distributed storage systems. Cisco AI POD designs may use dedicated storage-leaf connectivity to prevent storage traffic from interfering with backend GPU collective communication. The management network serves out-of-band management interfaces for servers, switches, storage platforms, and other infrastructure components. Cisco AI reference architectures explicitly distinguish backend, frontend/storage, and management connectivity for these purposes.

Maintaining these traffic domains independently improves deterministic performance, fault isolation, congestion control, security, and operational manageability.

Study Guide Reference: AI Infrastructure Components and Architecture — network fabrics, bandwidth, latency, scalability, and AI infrastructure connectivity.

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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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Traffic Analytics and Flow Telemetry are mutually exclusive flow-collection modes within Cisco Nexus Dashboard. Cisco's current Nexus Dashboard documentation identifies both under Flow Collection settings and states that Flow Telemetry must be disabled at the fabric level before Traffic Analytics can be enabled.

Traffic Analytics automatically discovers services and visualizes conversations based primarily on Layer 4 information. It provides visibility into network characteristics such as congestion, latency, and drops, which directly matches the monitoring requirements in the scenario. Cisco's Nexus Dashboard Insights guidance likewise states that if Flow Telemetry is already active, it must first be disabled for the relevant sites before Traffic Analytics is selected.

Delta Analysis is an assurance/comparison capability and is not the mutually exclusive collection mode described here. Connectivity Analysis performs reachability and path-oriented diagnostics. SNMP traps remain a separate event-notification mechanism and are not displaced by Traffic Analytics.

The operational distinction matters because Traffic Analytics and Flow Telemetry use different approaches to flow collection and analysis. An administrator cannot simply enable both collection modes simultaneously and expect them to operate in parallel on the same fabric configuration.

Study Guide Reference: AI Infrastructure Operations and Troubleshooting — Nexus Dashboard monitoring, telemetry, congestion analysis, latency, and packet-drop visibility.

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Cisco NX-OS configures interface-specific Dynamic Load Balancing through the DLB hardware profile , not independently under each physical interface. The administrator first enters hardware profile dlb and then uses dlb-interface within that submode to specify the interfaces on which DLB is enabled. Cisco's current Nexus 9000 documentation provides examples such as dlb-interface Eth1/5,Eth1/7,Eth1/17..., which directly supports selecting only odd-numbered interfaces.

Therefore, option C most accurately describes the required configuration: create or enter the DLB hardware profile and provide the selected interface list. Cisco also notes that changes to this interface list generally require a switch reload before they become effective.

Option A incorrectly implies that dlb-interface is applied in standard interface configuration mode. It is actually configured under the hardware profile dlb submode. Option B describes policy-driven DLB, which is a separate mechanism requiring QoS classification with set dlb mode; it is unnecessary when the requirement is simply to enable DLB on a predetermined set of interfaces. Option D reverses the logic and would not enable the requested interfaces.

Correction: the uploaded file marks A , but current Cisco NX-OS configuration documentation supports C as written.

Study Guide Reference: AI Infrastructure Deployment and Data Management — load distribution and Dynamic Load Balancing.

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Image recognition is a computer-vision application in which an AI model processes digital imagery and identifies meaningful visual content. Depending on the model and use case, the output can include image classifications, detected objects, faces, locations, labels, bounding boxes, or other semantic information describing what appears in the image. Therefore, detection and labeling of visual elements from digital sources is the correct result.

Cisco identifies computer vision as an established AI/ML workload and has used image-recognition techniques in technologies where models learn to identify objects despite variations in position and orientation. The DCAI exam blueprint requires candidates to understand AI use cases, making the distinction between computer-vision workloads and unrelated infrastructure functions important.

Option A is a security and compliance operation involving data anonymization. Option C is an infrastructure scheduling function generally performed by orchestration or management systems. Option D belongs to network control-plane and forwarding behavior and has no direct relationship to image recognition.

The key examination principle is that image recognition transforms unstructured visual input into meaningful classifications or detections that can subsequently drive automated decisions or analytics.

Study Guide Reference: 1.0 AI Fundamentals and Applications — 1.3 Describe AI use cases.

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The defining computational activity of model training is the iterative adjustment of the model's trainable parameters—principally weights and biases —to reduce an objective or loss function. During training, input examples are processed through the model, prediction error is calculated, gradients are derived, and an optimization algorithm updates parameters. Repetition across batches and epochs gradually produces a model that captures useful patterns and relationships in the training data.

Cisco identifies Training as a specific AI/ML workload type and separately requires knowledge of the overall AI lifecycle. Cisco's AI/ML operations guidance describes model training as the process through which a model learns patterns, features, representations, and relationships from data and places training before deployment and production operation.

Option A represents deployment or application integration after training. Option B normally belongs to problem definition and project-planning stages before model development. Option D is a production-monitoring activity used to determine whether a deployed model's behavior has degraded or changed because incoming data or underlying relationships have shifted.

Therefore, C identifies the central learning mechanism occurring during the training stage.

Study Guide Reference: 1.0 AI Fundamentals and Applications — 1.1.b Training; 1.2 Describe the AI lifecycle.

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Cisco Intersight provides comprehensive infrastructure monitoring that extends beyond conventional CPU and memory health reporting to AI accelerator visibility and performance telemetry . Cisco's current Intersight material specifically highlights GPU performance visibility, resource-utilization trends, power consumption, device health, and Metrics Explorer as important capabilities for managing AI-ready infrastructure.

This makes option D the only answer that addresses all three requirements: direct GPU visibility, detection of resource bottlenecks, and overall compute health. Monitoring GPU utilization, memory consumption, power, and associated platform telemetry allows operators to determine whether an AI workload is constrained by the GPU itself or by supporting compute, memory, networking, storage, or thermal infrastructure.

Option A incorrectly characterizes an Intersight Analyze capability as an AI container and Kubernetes deployment engine. Option B identifies valuable complementary network telemetry through Nexus Dashboard, but the question asks specifically for the most critical Intersight capability for monitoring GPU-centric UCS infrastructure. Option C is contradicted by current Cisco capabilities because Intersight provides AI-accelerator and GPU-performance visibility rather than being restricted to basic CPU and memory telemetry.

Study Guide Reference: AI Infrastructure Operations and Troubleshooting — Cisco Intersight health monitoring, GPU telemetry, resource utilization, bottleneck identification, and AI infrastructure optimization.

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In an Intersight Managed Mode UCS domain, DNS and NTP configuration is policy-controlled through the UCS Domain Profile deployed to the Fabric Interconnects. Changes entered locally through the Device Console can restore temporary reachability, but the policy configuration maintained by Intersight remains authoritative. If the Domain Profile still contains the previous DNS or NTP configuration, a subsequent deployment can overwrite the locally modified values.

Cisco documents that the Domain Profile references both the Network Connectivity Policy , which contains DNS settings, and the NTP Policy , which defines the NTP servers. The appropriate persistent remediation is therefore to edit the configuration associated with the deployed Domain Profile and redeploy it.

The IMC Access Policy applies primarily to server-management addressing and access rather than Fabric Interconnect DNS/NTP persistence. A Device Connector policy does not supply these domain DNS settings. Option C incorrectly applies a Network Connectivity Policy to the blade chassis; for the Fabric Interconnect domain, the relevant network-connectivity configuration is referenced through the UCS Domain Profile.

Cisco also advises that DNS and NTP should be configured on the management interface rather than being treated as Device Connector settings.

Study Guide Reference: AI Infrastructure Deployment and Data Management — Intersight Managed Mode, UCS Domain Profiles, DNS/NTP policies, and management connectivity.

An IP-based shared storage array is the appropriate architecture for a RAG environment containing approximately 50 TB of enterprise documents. RAG requires compute nodes to access a common body of source documents, embeddings, vector indexes, model artifacts, and intermediate datasets. With six UCS X210c servers participating in the solution, centralized shared storage avoids creating isolated data silos on individual compute nodes and allows the full AI cluster to access the same authoritative dataset.

Cisco AI POD and RAG architectures use enterprise shared storage connected through high-speed Ethernet. Cisco validates IP-based protocols including NFS, iSCSI, NVMe/TCP, and—in higher-performance AI platforms—RDMA-capable storage designs. Cisco's RAG architecture with FlexPod, for example, uses NFS, iSCSI, and NVMe/TCP storage networks, while Cisco AI PODs support external storage from partners such as NetApp, Pure Storage, and VAST Data.

JBOD and RAID 5 local storage remain tied to individual servers and do not provide the desired shared data layer. Tape provides economical archival retention but lacks the random-access latency and throughput required for active RAG retrieval.

Study Guide Reference: AI Infrastructure Components and Architecture — storage selection, AI data access, scalability, RAG infrastructure, and shared storage.

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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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