The answer is that the 'switchport access vlan 20' command is missing or incorrect. When a switchport lacks an explicit access VLAN assignment, it defaults to VLAN 1, which is why the PC receives broadcasts only from that default VLAN instead of the intended VLAN 20. This scenario tests your understanding of Layer 2 switchport configuration, a core skill for the CCNA 200-301 v2 exam, where a common trap is assuming a port automatically inherits a VLAN from a neighboring device or that simply setting the interface to 'switchport mode access' is enough. The key is that 'switchport mode access' only sets the port to operate in access mode, but without the accompanying 'switchport access vlan 20' command, the port remains in VLAN 1. A reliable memory tip is: "Mode sets the door, VLAN sets the room"—the mode command opens the door for access, but the VLAN command assigns the specific room number.
CCNA Switching and Network Access Practice Question
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. 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 PC connected to switch port Gi0/10 should be in VLAN 20 but receives broadcasts only from VLAN 1. Which switchport setting is most likely wrong?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
switchport access vlan 20 missing or incorrect
The PC is receiving broadcasts only from VLAN 1, which indicates the switchport is not correctly assigned to VLAN 20. The most likely cause is that the 'switchport access vlan 20' command is missing or incorrect, leaving the port in its default VLAN (VLAN 1). This prevents the PC from participating in VLAN 20 and receiving its broadcasts.
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.
✗
switchport mode trunk
Why it's wrong here
A user-facing PC port normally should not be trunking, but the symptom described specifically points to VLAN membership assignment.
When this WOULD be correct
In a scenario where the question specifies that a switch port should be configured to allow multiple VLANs for a server that needs to communicate across VLANs, the correct answer would be that the switchport mode trunk is incorrectly set to access mode. This would lead to the server not receiving broadcasts from the required VLANs.
✓
switchport access vlan 20 missing or incorrect
Why this is correct
Correct. The access VLAN setting most directly controls this behavior.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
speed 1000
Why it's wrong here
Speed mismatch can cause link issues, not incorrect VLAN broadcast membership.
When this WOULD be correct
In a different scenario, if a question asked about a switch port configuration issue causing a device to experience connectivity problems due to mismatched speeds between the switch and the connected device, then 'speed 1000' could be the correct answer if the device only supports lower speeds, leading to a failure in communication.
In a different scenario where the question asks about the performance of a network connection, a candidate might be asked what could cause a device to experience packet loss or communication issues. If the question specifies that the switch port is set to 'half duplex', then 'duplex full' would be the correct answer as it would resolve the communication issue.
Option-by-option analysis
Why each answer is right or wrong
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.
✓switchport access vlan 20 missing or incorrectCorrect answer▾
Why this is correct
Correct. The access VLAN setting most directly controls this behavior.
✗switchport mode trunkWrong answer — click to see why▾
Why this is wrong here
The switchport mode trunk setting is incorrect because a trunk port allows multiple VLANs to pass, while the question indicates that the PC should only receive broadcasts from VLAN 20. Therefore, the issue lies with the access VLAN configuration.
★ When this WOULD be the correct answer
In a scenario where the question specifies that a switch port should be configured to allow multiple VLANs for a server that needs to communicate across VLANs, the correct answer would be that the switchport mode trunk is incorrectly set to access mode. This would lead to the server not receiving broadcasts from the required VLANs.
Why candidates choose this
Candidates may choose this option because they associate trunking with VLAN communication and might overlook the specific requirement for the PC to be in a single VLAN, leading to confusion about the port's intended configuration.
✗speed 1000Wrong answer — click to see why▾
Why this is wrong here
The speed setting of 1000 Mbps (1 Gbps) does not influence VLAN membership or broadcast traffic; it only affects the data transfer rate. Therefore, this option does not address the issue of the PC receiving broadcasts only from VLAN 1.
★ When this WOULD be the correct answer
In a different scenario, if a question asked about a switch port configuration issue causing a device to experience connectivity problems due to mismatched speeds between the switch and the connected device, then 'speed 1000' could be the correct answer if the device only supports lower speeds, leading to a failure in communication.
Why candidates choose this
Candidates might choose this option because they associate speed settings with connectivity issues, mistakenly believing that incorrect speed configurations could impact VLAN membership or broadcast traffic.
✗duplex fullWrong answer — click to see why▾
Why this is wrong here
The duplex setting of the switch port does not influence VLAN membership or broadcast traffic. Therefore, a duplex configuration of 'full' does not affect the ability of a PC to receive broadcasts from VLAN 20.
★ When this WOULD be the correct answer
In a different scenario where the question asks about the performance of a network connection, a candidate might be asked what could cause a device to experience packet loss or communication issues. If the question specifies that the switch port is set to 'half duplex', then 'duplex full' would be the correct answer as it would resolve the communication issue.
Why candidates choose this
Candidates may mistakenly believe that duplex settings impact VLAN functionality, leading them to choose this option when they see issues with broadcast traffic, despite it being unrelated.
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
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a trunk port is needed for VLAN membership, but for a single end device, an access port with the correct VLAN assignment is required.
Detailed technical explanation
How to think about this question
When a switchport is in access mode, it belongs to a single VLAN, and all frames are untagged. The default VLAN for all switchports is VLAN 1 unless explicitly changed with 'switchport access vlan <vlan-id>'. If the access VLAN is not set to 20, the port remains in VLAN 1, so the PC will only see broadcasts from VLAN 1. This is a common misconfiguration when adding a new device to a specific VLAN without updating the port configuration.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
Switching and Network Access — This question tests Switching and Network Access — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: switchport access vlan 20 missing or incorrect — The PC is receiving broadcasts only from VLAN 1, which indicates the switchport is not correctly assigned to VLAN 20. The most likely cause is that the 'switchport access vlan 20' command is missing or incorrect, leaving the port in its default VLAN (VLAN 1). This prevents the PC from participating in VLAN 20 and receiving its broadcasts.
What should I do if I get this 200-301 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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