This 200-301 practice question tests your understanding of switching and network access. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: vLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing.. 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.
Hosts in VLAN 10 need to communicate with hosts in VLAN 20. What is required for that communication to work?
A DHCP server
Why wrong: DHCP provides addressing, not routing between VLANs.
A DNS server
Why wrong: DNS resolves names, not inter-VLAN paths.
A Layer 3 routing function
Correct. Layer 3 routing is required.
A second access switch
Why wrong: Another Layer 2 switch alone does not route between VLANs.
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 Layer 3 routing function
Traffic between VLANs must be routed. A router or multilayer switch provides the Layer 3 function needed for inter-VLAN communication.
Key principle: VLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
A DHCP server
Why it's wrong here
DHCP provides addressing, not routing between VLANs.
A DNS server
A Layer 3 routing function
Why this is correct
Correct. Layer 3 routing is required.
Related concept
VLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing.
A second access switch
Why it's wrong here
Another Layer 2 switch alone does not route between VLANs.
When this WOULD be correct
If the exam question specified that the network was experiencing performance issues due to too many VLANs being managed by a single switch, and suggested that adding a second access switch could help distribute the load and improve communication efficiency, then this option would be correct.
Option-by-option analysis
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
Why this is correct
Correct. Layer 3 routing is required.
Why this is wrong here
A DHCP server is not required for communication between VLANs; it only assigns IP addresses to devices within a network. VLAN communication requires routing, which a DHCP server does not provide.
★ When this WOULD be the correct answer
If the question asked about enabling IP address assignment for hosts in VLAN 10 and VLAN 20, where both VLANs are on the same network segment, then a DHCP server would be necessary to ensure that devices in both VLANs receive valid IP addresses.
Why candidates choose this
Candidates may confuse the need for IP address assignment with the requirement for inter-VLAN communication, leading them to believe that a DHCP server is essential for connectivity between VLANs.
Why this is wrong here
A DNS server is not required for VLAN communication, as DNS resolves domain names to IP addresses, which does not facilitate inter-VLAN routing. Communication between VLANs requires Layer 3 routing, not name resolution.
★ When this WOULD be the correct answer
In a question asking about network services needed for host name resolution in a multi-VLAN environment, where hosts in different VLANs need to resolve each other's domain names, a DNS server would be essential for that purpose.
Why candidates choose this
Candidates may confuse the need for network services in a multi-VLAN setup, mistakenly believing that DNS is necessary for communication, as it is often associated with network functionality and connectivity.
Why this is wrong here
A second access switch is not required for VLAN communication; VLANs can communicate through a Layer 3 device such as a router or a Layer 3 switch. The existing switch infrastructure can handle VLANs without needing additional switches.
★ When this WOULD be the correct answer
If the exam question specified that the network was experiencing performance issues due to too many VLANs being managed by a single switch, and suggested that adding a second access switch could help distribute the load and improve communication efficiency, then this option would be correct.
Why candidates choose this
Candidates might choose this option because they associate VLANs with physical switch configurations and believe that additional hardware is necessary for inter-VLAN communication, overlooking the role of Layer 3 routing.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Do not confuse trunk links or access ports with routing functions; they serve different purposes in VLAN configurations.
Detailed technical explanation
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
Key takeaway
VLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing.
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 vLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
Switching and Network Access — This question tests Switching and Network Access — VLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing..
The correct answer is: A Layer 3 routing function — Traffic between VLANs must be routed. A router or multilayer switch provides the Layer 3 function needed for inter-VLAN communication.
Review vLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing., then practise related 200-301 questions on the same topic to reinforce the concept.
VLANs create separate broadcast domains that isolate traffic at Layer 2, preventing direct communication between different VLANs without routing.
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Last reviewed: May 17, 2026
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