NVIDIA NCP-AIN AI Networking Exam Practice Test

Answer : B

RoCE Adaptive Routing is a key feature of NVIDIA Spectrum-X that ensures high performance and resiliency in the network, even in the event of a link failure. This technology dynamically reroutes traffic to the least congested and operational paths, effectively mitigating the impact of link failures. By continuously evaluating the network's egress queue loads and receiving status notifications from neighboring switches, Spectrum-X can adaptively select optimal paths for data transmission. This ensures that the network maintains high throughput and low latency, crucial for AI workloads, even when certain links are down.

Reference Extracts from NVIDIA Documentation:

'Spectrum-X employs global adaptive routing to quickly reroute traffic during link failures, minimizing disruptions and preserving optimal storage fabric utilization.'

'RoCE Adaptive Routing avoids congestion by dynamically routing large AI flows away from congestion points. This approach improves network resource utilization, leaf/spine efficiency, and performance.'

Answer : B

Before upgrading the DOCA SDK on a BlueField DPU, it is mandatory to uninstall the existing OFED drivers to prevent compatibility conflicts.

From the NVIDIA DOCA Installation Guide:

'Before upgrading DOCA or BlueField-related software, you must remove existing OFED packages using: /usr/sbin/ofed_uninstall.sh -force.'

This ensures:

Clean driver state

No residual kernel modules or userspace libraries

Proper registration of new DOCA/OFED versions

Incorrect Options:

A and C may not resolve conflicts.

D installs but doesn't remove conflicting packages.

Answer : D

In NVIDIA Spectrum-X, congestion is evaluated based on egress queue loads. Spectrum-4 switches assess the load on each egress queue and select the port with the minimal load for packet transmission. This approach ensures that all ports are well-balanced, optimizing network performance and minimizing congestion.

Answer : B, D

In Cumulus Linux, microbursts are short-lived, high-volume traffic bursts that often go undetected by coarse-grained monitoring like SNMP.

The two tools specifically used for this purpose are:

What Just Happened (WJH)

'WJH provides real-time packet drop visibility and classifies drops by reason (e.g., congestion, ACLs, etc.), enabling microburst detection.'

ASIC monitoring at millisecond granularity

'Deep telemetry is enabled via the switch ASIC, which provides sub-second counters that capture microburst patterns otherwise missed by SNMP.'

Incorrect Options:

A and C provide low-frequency sampling, insufficient for microbursts which last milliseconds.

Answer : A

To enable RDMA over Converged Ethernet (RoCE) on a Cumulus switch, the correct command is:

nv set qos roce enable on

This command configures the Quality of Service (QoS) settings to support RoCE, ensuring that the necessary parameters for lossless Ethernet are applied.

Answer : C

The NVIDIA Spectrum-X networking platform is an Ethernet-based solution optimized for AI workloads, combining Spectrum-4 switches, BlueField-3 SuperNICs, and advanced software to deliver high performance and low latency. Gathering telemetry data is critical for optimizing Spectrum-X networks, as it provides visibility into network performance, congestion, and potential issues. The question asks for the tool used to collect telemetry data in a Spectrum-X network.

According to NVIDIA's official documentation, NVIDIA NetQ is the primary tool for gathering telemetry data in Ethernet-based networks, including those running on Spectrum-X platforms with Cumulus Linux or SONiC. NetQ is a network operations toolset that provides real-time monitoring, telemetry collection, and analytics for network health, enabling administrators to optimize performance, troubleshoot issues, and validate configurations. It collects detailed telemetry data such as link status, packet drops, latency, and congestion metrics, which are essential for Spectrum-X optimization.

Exact Extract from NVIDIA Documentation:

''NVIDIA NetQ is a highly scalable network operations tool that provides telemetry-based monitoring and analytics for Ethernet networks, including NVIDIA Spectrum-X platforms. NetQ collects real-time telemetry data from switches and hosts, offering insights into network performance, congestion, and connectivity. It supports Cumulus Linux and SONiC environments, making it ideal for optimizing Spectrum-X networks by providing visibility into key metrics like latency, throughput, and packet loss.''

--- NVIDIA NetQ User Guide

This extract confirms that option C, NetQ, is the correct tool for gathering telemetry data in a Spectrum-X network. NetQ's integration with Spectrum-X switches and its ability to collect and analyze telemetry data make it the go-to solution for network optimization tasks.

Answer : A

NVIDIA's What Just Happened (WJH) is a feature that provides real-time visibility into network problems by analyzing all packets passing through the switch and alerting on performance issues caused by packet drops, congestion, high latency, or misconfigurations.

WJH retains the last packets that were dropped from the switch with complete packet headers and the actual drop reason. This enhances the ability to debug network problems, identify affected flows, and decrease time-to-repair.