The correct choice is to use a virtual switch with port groups assigned to different VLANs. This configuration achieves VM isolation by leveraging VLANs to segment traffic at Layer 2 of the OSI model, allowing multiple virtual machines on the same physical network hardware to be logically separated for security. On the CompTIA A+ Core 1 220-1201 exam, this concept tests your understanding of how virtualization relies on logical segmentation rather than physical cabling to enforce boundaries—a common trap is confusing VLAN isolation with a separate physical switch, which is unnecessary when a virtual switch can tag traffic per port group. Remember that VLANs act like invisible walls between VMs sharing a single wire; a helpful memory tip is “VLANs carve a single pipe into private lanes,” reinforcing that isolation happens through tagging, not hardware.
220-1201 Virtualization Concepts Practice Question
This 220-1201 practice question tests your understanding of virtualization concepts. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company needs to deploy a virtualized environment where each VM must be isolated from others for security reasons, but all VMs share the same physical network. Which virtual networking configuration should be used?
Use a virtual switch with port groups assigned to different VLANs
VLAN tagging on virtual switch port groups isolates traffic between VMs while sharing the same physical interface.
B
Configure each VM with a different MAC address
Why wrong: Different MAC addresses do not provide isolation; VMs can still communicate freely.
C
Use bridged networking for all VMs
Why wrong: Bridged networking connects VMs directly to the physical network without isolation.
D
Assign each VM a static IP address from a different subnet
Why wrong: Different subnets require a router to communicate, but VMs on the same VLAN can still reach each other via the default gateway unless firewalled.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a virtual switch with port groups assigned to different VLANs
VLANs provide network isolation at Layer 2, allowing VMs on the same physical network to be separated logically. This is a common security practice in virtualized environments.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Use a virtual switch with port groups assigned to different VLANs
Why this is correct
VLAN tagging on virtual switch port groups isolates traffic between VMs while sharing the same physical interface.
Related concept
Access ports place end devices into a single VLAN.
✗
Configure each VM with a different MAC address
Why it's wrong here
Different MAC addresses do not provide isolation; VMs can still communicate freely.
✗
Use bridged networking for all VMs
Why it's wrong here
Bridged networking connects VMs directly to the physical network without isolation.
✗
Assign each VM a static IP address from a different subnet
Why it's wrong here
Different subnets require a router to communicate, but VMs on the same VLAN can still reach each other via the default gateway unless firewalled.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
→Use show vlan brief to verify access VLANs.
→Use show interfaces trunk to verify trunk state and allowed VLANs.
→Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 220-1201 questions on switching, trunking, and access-port configuration.
Virtualization Concepts — This question tests Virtualization Concepts — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Use a virtual switch with port groups assigned to different VLANs — VLANs provide network isolation at Layer 2, allowing VMs on the same physical network to be separated logically. This is a common security practice in virtualized environments.
What should I do if I get this 220-1201 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 220-1201 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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