This 200-901 practice question tests your understanding of network fundamentals. 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.
Exhibit
Refer to the exhibit.
```
Switch# show vlan brief
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Gi0/1, Gi0/2
10 Engineering active Gi0/3, Gi0/4
20 Marketing active Gi0/5, Gi0/6
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
```
Refer to the exhibit. A switch has the VLAN configuration shown. If a device is connected to interface Gi0/3 and another to Gi0/5, can they communicate if the switch is not configured with any inter-VLAN routing?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No, because they are in different VLANs and no routing is configured.
Option C is correct because devices in different VLANs (VLAN 10 and VLAN 20) are on separate Layer 2 broadcast domains. Without inter-VLAN routing (either a Layer 3 switch with IP routing enabled or an external router), traffic cannot cross VLAN boundaries, even if the devices share the same physical switch. The switch forwards frames only within the same VLAN unless routing is explicitly configured.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Yes, if the default gateway is configured on each device.
Why it's wrong here
Default gateway is needed for inter-VLAN, but without a router it still fails.
Read the scenario before looking for a memorised answer.
✗
Yes, if the devices have IP addresses in the same subnet.
Why it's wrong here
Even if same subnet, they are on different broadcast domains.
✗
Yes, because all ports are on the same switch.
Why it's wrong here
Same switch does not guarantee communication across VLANs.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume all ports on the same switch can communicate by default, overlooking that VLANs create isolated Layer 2 domains that require routing to interconnect.
Detailed technical explanation
How to think about this question
Under the hood, VLANs segment the switch's MAC address table and forwarding logic per VLAN ID. When a frame arrives on an access port, the switch tags it internally with the port's VLAN ID and forwards it only to ports in that same VLAN. For inter-VLAN communication, the switch must perform IP routing (using a switched virtual interface or an external router) to forward packets between VLANs, which requires the switch to operate at Layer 3. In real-world scenarios, this is why a Layer 3 switch or router-on-a-stick is used to enable communication between VLANs.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: No, because they are in different VLANs and no routing is configured. — Option C is correct because devices in different VLANs (VLAN 10 and VLAN 20) are on separate Layer 2 broadcast domains. Without inter-VLAN routing (either a Layer 3 switch with IP routing enabled or an external router), traffic cannot cross VLAN boundaries, even if the devices share the same physical switch. The switch forwards frames only within the same VLAN unless routing is explicitly configured.
What should I do if I get this 200-901 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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