VCP-DCV vSphere Security Practice Question
A security administrator notices that a virtual machine (VM) running a legacy application is experiencing network connectivity issues after enabling Network I/O Control (NIOC) on the distributed switch. The VM is in a high-priority traffic class for management traffic. What is the most likely cause of the issue?
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
✓
The VM is assigned to the management traffic class, but its traffic should be in a different class, causing bandwidth throttling.
NIOC traffic classes assign bandwidth shares and limits per class. If the VM's traffic (legacy application) is placed in the management traffic class, it will be subject to the bandwidth constraints of that class, which may cause connectivity issues if the application requires more bandwidth or different QoS. Option A is incorrect because NIOC does not block MAC addresses; MAC address blocking is a security policy on the distributed switch port group. Option C is incorrect because NIOC supports jumbo frames; jumbo frames are configured at the VM or vSwitch level and do not conflict with NIOC. Option D is incorrect because promiscuous mode is a port group security setting unrelated to NIOC; NIOC manages bandwidth allocation and does not interfere with promiscuous mode.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
NIOC is blocking the VM's MAC address due to a security policy.
Why it's wrong here
NIOC does not filter based on MAC; it manages bandwidth allocation.
- ✓
The VM is assigned to the management traffic class, but its traffic should be in a different class, causing bandwidth throttling.
Why this is correct
NIOC classes limit bandwidth; wrong class assignment can restrict traffic.
- ✗
The VM is using jumbo frames, which are not supported with NIOC.
Why it's wrong here
Jumbo frames are supported with NIOC, as they are independent features.
- ✗
The virtual switch has promiscuous mode enabled, which conflicts with NIOC.
Why it's wrong here
Promiscuous mode is a security policy, not related to NIOC bandwidth management.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This VCP-DCV practice question is part of Courseiva's free VMware 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 VCP-DCV exam.