Cisco Updated 300-640 Exam Questions and Answers by alvie

Retrieval-Augmented Generation enhances an LLM by retrieving relevant information from external knowledge sources and incorporating that material into the context supplied to the model during generation. This permits a pretrained model to answer questions using organization-specific information without requiring its underlying model parameters to be retrained for every knowledge update.

Cisco describes RAG as a technique that connects LLM applications to additional data sources, including internal repositories containing sensitive customer or business information. Cisco's enterprise RAG guidance specifically emphasizes using proprietary organizational data to ground responses in enterprise information. Therefore, providing access to proprietary data is the correct answer.

Option A is incorrect because RAG does not eliminate ingestion, parsing, chunking, cleaning, embedding, or indexing requirements. Option B is too absolute: grounding can improve factual relevance but does not inherently remove model bias. Option D describes modification of model parameters, which is characteristic of training or fine-tuning rather than standard RAG retrieval.

Cisco explicitly includes RAG as a required DCAI workload type, so candidates must distinguish retrieval-based augmentation from model training and fine-tuning.

Study Guide Reference: 1.0 AI Fundamentals and Applications — 1.1.a RAG.

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NVIDIA Collective Communications Library (NCCL) is the appropriate framework for validating communication performance between NVIDIA GPU nodes. NCCL provides highly optimized implementations of collective operations such as AllReduce, AllGather, Reduce, Broadcast, and ReduceScatter. These operations closely represent the communication patterns generated by distributed AI training and therefore provide much more meaningful validation of GPU-cluster performance than conventional network-throughput tests.

NCCL-based benchmarks can reveal whether GPU-to-GPU communication is achieving expected bandwidth and latency across NVLink, PCIe, and the external backend network. They are particularly useful when validating RoCEv2 fabrics because distributed training performance depends on collective communication efficiency rather than simple host-to-host TCP throughput.

iPerf measures conventional TCP or UDP network performance between hosts and is useful for basic network validation, but it does not exercise NVIDIA GPU collective communications. Spirent and Ixia provide sophisticated packet-generation and network-testing platforms, yet they test the network primarily from a packet-forwarding perspective rather than measuring actual GPU collective-operation behavior.

For a newly deployed NVIDIA AI cluster, NCCL benchmarking therefore provides workload-representative validation of the end-to-end GPU communication architecture and can expose problems involving topology, NIC configuration, congestion control, bandwidth imbalance, or fabric design.

Study Guide Reference: AI Infrastructure Operations and Troubleshooting — performance benchmarking, NVIDIA GPU communications, backend-fabric validation, and distributed AI workload testing.

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Cisco Nexus 9000 integration with NVIDIA adaptive-routing capabilities requires the Nexus switch to enable the Spectrum-X hardware profile . Cisco's current NX-OS configuration guide explicitly specifies the global configuration command hardware profile spectrum-x to enable NVIDIA Spectrum-X adaptive routing. When a Nexus switch peers with a supported NVIDIA NIC, this capability allows the NIC to handle packet reordering created by granular techniques such as per-packet Dynamic Load Balancing.

This is particularly important for AI training because large synchronized RDMA flows can create uneven utilization under conventional hash-based ECMP. Cisco explains that per-packet DLB can spray packets over multiple paths and that NVIDIA adaptive routing/direct data placement enables the receiver to correctly handle packets that arrive out of order, improving utilization and collective-operation performance.

Option A is not the documented NX-OS configuration syntax. Option B is not the Cisco-prescribed Nexus integration command. Option D may be relevant to traffic classification in other designs but does not activate Spectrum-X adaptive-routing interoperability.

Therefore, the Cisco-documented configuration is C. This differs from the supplied file's marked answer B.

Study Guide Reference: 3.0 AI Infrastructure Deployment and Data Management — 3.1.d Load distribution.

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