300-640 DCAI study guide
300-640 DCAI · Work through your exam, one topic at a time.
The Designing Cisco Data Center AI Infrastructure (300-640 DCAI) exam is a Cisco specialist-level certification exam focused on planning and designing data center infrastructure for AI and machine learning workloads. It targets data center architects, pre-sales and design engineers, and senior network or compute engineers who translate AI workload requirements into validated data center designs. The 300-640 DCAI study guide has 6 sections and about 2,568 words.
01AI Infrastructure Architecture and Design
This domain tests whether you can turn an AI workload profile - model size, parallelism strategy, dataset scale, job duration, inference latency target - into a physical and logical Cisco design: rack layout, power and cooling envelope, compute/storage/management planes, and the management stack that ties them together. Performance: AI traffic is east-west and many-to-many.
451 words, about 2 min02Compute and GPU Fabric for AI Workloads
This domain covers the server side of an AI cluster: how Cisco UCS platforms place GPUs, how those GPUs are wired internally (PCIe versus NVLink), how the server connects to the AI fabric through the Fabric Interconnect, and how Cisco Intersight applies BIOS, firmware, and connectivity policy consistently across the domain. UCS X-Series (X9508 7RU chassis, up to 8 compute nodes) accepts the X440p PCIe node, which carries up to 4 double-wide GPUs per node.
434 words, about 2 min03AI/ML Storage and Data Management
This domain tests how you feed GPUs and protect training progress: choosing the right storage tier and protocol, sizing capacity and bandwidth, and integrating storage traffic into the Cisco network without damaging the lossless AI fabric. Parallel file systems (scratch and hot datasets) deliver aggregate bandwidth by striping across many servers.
404 words, about 2 min04High-Speed AI Networking and Fabric Design
This domain tests the lossless Ethernet design that carries RDMA: RoCEv2 classification, PFC, ECN, MTU consistency, topology choice, and the operational telemetry that keeps a congested fabric from collapsing. RoCEv2 encapsulates RDMA in UDP destination port 4791.
425 words, about 2 min05Automation, Orchestration, and Operations
This domain tests how you build and run an AI fabric repeatably: a source of truth, template-driven configuration, programmatic interfaces, and telemetry-driven validation instead of CLI sessions on individual switches. Cisco Nexus Dashboard is the operations platform hosting NDFC (fabric controller), NDI (Insights, for analytics and validation), and NDO (Orchestrator, for multi-site policy).
395 words, about 2 min06Security, Resiliency, and Sustainability
This domain tests the operational qualities of an AI fabric: isolating tenants and management traffic, protecting data in flight, surviving component and congestion failures, and running GPU-dense infrastructure within a credible power and cooling envelope. Segmentation: separate VRFs per tenant and per function (compute, storage, management, OOB), enforced with ACLs and, where deployed, Cisco TrustSec group tags so policy follows the workload rather than the subnet.
459 words, about 2 min