Quick Answer
The correct answer is a router or a Layer 3 switch. This is because VLANs create separate broadcast domains, isolating traffic for security, and a Layer 2 switch can only forward frames within the same VLAN; it cannot route between them. Inter-VLAN routing requires a Layer 3 device that can inspect IP addresses and make forwarding decisions across different subnets. On the CompTIA A+ Core 1 220-1201 exam, this concept often appears in troubleshooting scenarios where users on different floors or departments cannot communicate, testing your understanding that a router or Layer 3 switch is the missing link. A common trap is assuming a single switch can handle all traffic, but remember: Layer 2 switches are blind to IP routing. For a quick memory tip, think “VLANs need a router to talk across the border.”
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 technician is troubleshooting a network where users on one floor cannot communicate with users on another floor. Both floors are connected to the same switch via separate VLANs configured for security. What additional device is needed to allow communication between the VLANs?
A hub
Why wrong: A hub is a Layer 1 device that cannot route between VLANs.
A Layer 2 switch
Why wrong: A Layer 2 switch can create VLANs but cannot route between them without a router.
A router or Layer 3 switch
A router or Layer 3 switch can route traffic between VLANs, enabling inter-VLAN communication.
A bridge
Why wrong: A bridge connects two network segments but does not route between VLANs; it is a Layer 2 device.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A router or Layer 3 switch
VLANs segment a network into separate broadcast domains, and by default, they cannot communicate with each other. A Layer 3 device, such as a router or a Layer 3 switch, is required to route traffic between VLANs. A Layer 2 switch cannot perform routing. The correct answer is a router or a Layer 3 switch.
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
For each option: why learners choose it and why it is or isn't the right answer here.
A hub
Why it's wrong here
A hub is a Layer 1 device that cannot route between VLANs.
A Layer 2 switch
Why it's wrong here
A Layer 2 switch can create VLANs but cannot route between them without a router.
A router or Layer 3 switch
A bridge
Why it's wrong here
A bridge connects two network segments but does not route between VLANs; it is a Layer 2 device.
Common exam traps
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
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.
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
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
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
Common Networking Hardware — This question tests Common Networking Hardware — Access ports place end devices into a single VLAN..
The correct answer is: A router or Layer 3 switch — VLANs segment a network into separate broadcast domains, and by default, they cannot communicate with each other. A Layer 3 device, such as a router or a Layer 3 switch, is required to route traffic between VLANs. A Layer 2 switch cannot perform routing. The correct answer is a router or a Layer 3 switch.
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.
Access ports place end devices into a single VLAN.
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Last reviewed: Jun 18, 2026
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