- A
Create two separate subnets and connect each department to a different physical switch
Why wrong: This would require additional hardware (another switch) and does not utilize the single managed switch; VLANs are more efficient.
- B
Configure VLANs on the switch and set up a trunk port to the router with subinterfaces
VLANs isolate traffic, and the trunk with subinterfaces (router-on-a-stick) allows the router to route between VLANs and to the internet.
- C
Assign static IPs to all devices and enable MAC address filtering on the switch
Why wrong: MAC filtering controls which devices connect but does not segment traffic; all devices would still be on the same broadcast domain.
- D
Use a firewall between the two departments and disable inter-VLAN routing
Why wrong: This adds complexity and cost; VLANs with proper routing policies are the standard method for segmentation on a single switch.
Quick Answer
The correct choice is to configure VLANs on the switch and set up a trunk port to the router with subinterfaces. This approach achieves VLAN segmentation for department isolation by logically separating accounting and HR traffic on the same physical switch, preventing unauthorized access between them, while the trunk port carries those multiple VLANs to the router. The router then uses subinterfaces—one per VLAN—in a router-on-a-stick configuration to route traffic between departments and out to the internet. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of how VLANs and trunking work together to solve a real-world network security need without adding extra hardware. A common trap is thinking a second switch or separate router ports are required, but a single managed switch and one trunk link are sufficient. Memory tip: think of the trunk as a highway carrying multiple lanes (VLANs), and the router’s subinterfaces as the on-ramps that keep each lane’s traffic separate until routing is needed.
220-1101 Network Configuration Concepts Practice Question
This 220-1201 practice question tests your understanding of network configuration 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 network administrator needs to segment traffic between the accounting and HR departments to prevent unauthorized access, while still allowing both to reach the internet. The company uses a single managed switch and a router. Which configuration approach meets these requirements?
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
Configure VLANs on the switch and set up a trunk port to the router with subinterfaces
VLANs logically separate network traffic on the same switch, allowing different departments to be isolated. A trunk port carries multiple VLANs to the router, which can route between them and to the internet using a router-on-a-stick configuration.
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.
- ✗
Create two separate subnets and connect each department to a different physical switch
Why it's wrong here
This would require additional hardware (another switch) and does not utilize the single managed switch; VLANs are more efficient.
- ✓
Configure VLANs on the switch and set up a trunk port to the router with subinterfaces
- ✗
Assign static IPs to all devices and enable MAC address filtering on the switch
Why it's wrong here
MAC filtering controls which devices connect but does not segment traffic; all devices would still be on the same broadcast domain.
- ✗
Use a firewall between the two departments and disable inter-VLAN routing
Why it's wrong here
This adds complexity and cost; VLANs with proper routing policies are the standard method for segmentation on a single switch.
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.
What to study next
Got this wrong? Here's your next step.
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.
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Network Configuration Concepts — This question tests Network Configuration Concepts — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Configure VLANs on the switch and set up a trunk port to the router with subinterfaces — VLANs logically separate network traffic on the same switch, allowing different departments to be isolated. A trunk port carries multiple VLANs to the router, which can route between them and to the internet using a router-on-a-stick configuration.
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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Last reviewed: Jun 18, 2026
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