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350-401 Practice Question: Virtualizing its network functions using NFV on a…
A company is virtualizing its network functions using NFV on a KVM-based hypervisor. The design must ensure that the virtual router (CSR1000v) can handle high-throughput traffic with minimal latency. Which architectural consideration is most critical for achieving this goal?
⚠ Common exam trap
Cisco often tests the misconception that simply using a Type 1 hypervisor or avoiding overcommitment is sufficient, but the trap here is that candidates overlook the critical impact of NUMA locality and vCPU pinning on latency-sensitive VNFs, assuming that any virtualization optimization will suffice.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Pin the vCPU of the CSR1000v to dedicated physical cores and ensure the VM memory is allocated from the same NUMA node.
Pinning vCPUs to dedicated physical cores and allocating memory from the same NUMA node eliminates cross-NUMA memory access and CPU scheduling contention, which are critical for reducing latency and maximizing throughput in a data-plane-intensive VNF like the CSR1000v. This ensures that the VM's memory accesses are local to the NUMA node where its vCPUs run, avoiding the performance penalty of remote memory access over the QPI/UPI interconnect.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Pin the vCPU of the CSR1000v to dedicated physical cores and ensure the VM memory is allocated from the same NUMA node.
Why this is correct
CPU pinning and NUMA locality reduce latency and improve performance by avoiding cross-NUMA memory access.
- ✗
Use a Type 2 hypervisor to allow the VNF to share resources with other VMs more efficiently.
Why it's wrong here
Type 2 hypervisors add overhead; Type 1 (bare-metal) is preferred for performance-sensitive VNFs.
- ✗
Enable overcommitment of CPU resources to maximize the number of VNFs per host.
Why it's wrong here
Overcommitment can cause CPU contention, increasing latency and reducing throughput for the CSR1000v.
- ✗
Place the CSR1000v on a VMware ESXi host instead of KVM for better performance.
Why it's wrong here
Both hypervisors can perform well with proper tuning; the key is CPU pinning and NUMA awareness, not the hypervisor brand.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.