- A
Configure the router to use DHCP for the guest network.
Why wrong: DHCP only assigns IP addresses; it does not provide isolation. Guests would still be able to communicate with internal devices if they are on the same subnet.
- B
Create a separate VLAN for the guest network and apply an ACL to block traffic to the internal network.
VLANs logically separate traffic, and ACLs on the router can block inter-VLAN communication, ensuring guests cannot access internal resources while still allowing internet access.
- C
Disable the SSID broadcast for the guest network.
Why wrong: Hiding the SSID does not provide security or isolation; it only makes the network less visible. Guests could still access internal devices if on the same network.
- D
Use a wireless access point with a built-in firewall.
Why wrong: While a firewall can help, the question specifies using a single router and switch. The most straightforward solution is VLAN and ACL configuration on the router.
Quick Answer
The correct answer is to create a separate VLAN for the guest wireless network and apply an ACL to block traffic to the internal corporate subnet. This works because VLANs logically segment the network at Layer 2, isolating guest traffic into its own broadcast domain, while an access control list (ACL) on the router’s inter-VLAN interface enforces Layer 3 filtering—denying packets destined for the internal IP range while permitting internet-bound traffic. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of network segmentation and security best practices; a common trap is assuming a simple SSID change or a firewall rule on the switch alone will suffice, but without VLAN isolation and ACL enforcement, guests could still reach internal devices via the router’s default routing. Remember the memory tip: “VLAN to divide, ACL to hide”—the VLAN splits the traffic, and the ACL blocks the path to the internal network.
220-1201 Common Networking Hardware Practice Question
This 220-1201 practice question tests your understanding of common networking hardware. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 is setting up a guest wireless network in a conference room. They want to ensure that guests can access the internet but cannot communicate with internal corporate devices. The network uses a single router and a switch. Which configuration on the router will best achieve this?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Create a separate VLAN for the guest network and apply an ACL to block traffic to the internal network.
This question tests knowledge of VLANs and network segmentation. To isolate guest traffic from internal devices, the best practice is to create a separate VLAN for the guest network and configure access control lists (ACLs) to block inter-VLAN traffic. The correct answer is to set up a guest VLAN with an ACL that denies traffic to the internal subnet.
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.
- ✗
Configure the router to use DHCP for the guest network.
Why it's wrong here
DHCP only assigns IP addresses; it does not provide isolation. Guests would still be able to communicate with internal devices if they are on the same subnet.
- ✓
Create a separate VLAN for the guest network and apply an ACL to block traffic to the internal network.
Why this is correct
VLANs logically separate traffic, and ACLs on the router can block inter-VLAN communication, ensuring guests cannot access internal resources while still allowing internet access.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
- ✗
Disable the SSID broadcast for the guest network.
Why it's wrong here
Hiding the SSID does not provide security or isolation; it only makes the network less visible. Guests could still access internal devices if on the same network.
- ✗
Use a wireless access point with a built-in firewall.
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?
Common Networking Hardware — This question tests Common Networking Hardware — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: Create a separate VLAN for the guest network and apply an ACL to block traffic to the internal network. — This question tests knowledge of VLANs and network segmentation. To isolate guest traffic from internal devices, the best practice is to create a separate VLAN for the guest network and configure access control lists (ACLs) to block inter-VLAN traffic. The correct answer is to set up a guest VLAN with an ACL that denies traffic to the internal subnet.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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