CCNA Switching and Network Access Practice Question
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?
⚠ Common exam trap
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.
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
✓
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.
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
Configuring the port as a trunk makes it carry multiple VLAN-tagged frames, whereas an access port carries only untagged frames in a single VLAN. A PC NIC typically does not tag frames, so a trunk port would not correctly deliver VLAN 20 traffic to it; however, the symptom of a PC not being in the expected VLAN is most directly traced to the missing or incorrect 'switchport access vlan 20' statement, not the trunk mode itself. Even if trunk mode were the issue, the fix would still involve setting the correct access VLAN.
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
The access VLAN assignment on a switchport determines which untagged (native) VLAN the port belongs to. If a PC on interface Gi0/10 should be in VLAN 20 but is not, the most direct cause is that the port is either left in the default VLAN (often VLAN 1) or configured with a different access VLAN via the 'switchport access vlan' command. Without this correct mapping, the PC's frames are forwarded in the wrong broadcast domain and cannot reach VLAN 20 resources. This is the primary configuration that controls the behavior described.
- ✗
speed 1000
Why it's wrong here
The port speed setting is a physical-layer parameter that only governs link negotiation and data rate, not Layer 2 VLAN membership. A speed mismatch could prevent the link from coming up, but if the PC is communicating at all, the speed setting has no bearing on which VLAN the port is assigned to. Since the symptom is specifically about broadcast domain membership, speed is not the cause.
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.
- ✗
duplex full
Why it's wrong here
Duplex configuration (full or half) controls whether a link can send and receive simultaneously and is unrelated to VLAN assignment at Layer 2. A duplex mismatch causes collisions, frame errors, or poor performance, but it will not change the broadcast domain or the access VLAN that the port belongs to. Thus, it cannot explain why the PC is not in VLAN 20.
When this WOULD be correct
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
The access VLAN assignment on a switchport determines which untagged (native) VLAN the port belongs to. If a PC on interface Gi0/10 should be in VLAN 20 but is not, the most direct cause is that the port is either left in the default VLAN (often VLAN 1) or configured with a different access VLAN via the 'switchport access vlan' command. Without this correct mapping, the PC's frames are forwarded in the wrong broadcast domain and cannot reach VLAN 20 resources. This is the primary configuration that controls the behavior described.
✗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?”
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Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
VLAN
A VLAN logically segments a physical network into isolated broadcast domains without requiring separate physical switches.
Key term
Default VLAN
The Default VLAN is VLAN 1 on most Cisco switches and it is the VLAN to which all switch ports belong by default until they are assigned to a different VLAN.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.