CCNA Switching and Network Access Practice Question
A switch port connected to a user PC is configured as a trunk. The PC cannot communicate normally. What is the best explanation?
⚠ Common exam trap
Be careful not to confuse physical link issues with logical configuration mismatches. A trunk port on a user PC is a logical mismatch, not a hardware failure.
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
✓
The port role is wrong because a normal PC-facing switchport should usually be an access port, not a trunk
The best explanation is that the port role is wrong: a PC-facing port should be an access port, not a trunk, because PCs normally send untagged frames and cannot process VLAN tags. Option B is incorrect because EtherChannel is used for link aggregation, not required for a single PC. Option C is wrong because trunk mode does not disable MAC address learning. Option D is irrelevant, as switches do not stop using IP addressing in trunk mode.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The port role is wrong because a normal PC-facing switchport should usually be an access port, not a trunk
Why this is correct
A normal PC expects to receive and send untagged Ethernet frames in a single VLAN, so the switchport facing it should be an access port assigned to one access VLAN. Configuring it as a trunk makes the switch tag frames with 802.1Q headers, which the PC's NIC typically cannot process, breaking connectivity. Thus the port role is the primary misconfiguration.
- ✗
A user PC requires EtherChannel to function
Why it's wrong here
EtherChannel bundles multiple physical links into one logical link to increase bandwidth and provide redundancy, and it is designed for switch-to-switch or switch-to-server connections with multiple NICs. A typical user PC has a single network interface and does not generate enough traffic to require link aggregation. Even if it did, EtherChannel configuration on one side alone would not make the PC function; it is not a prerequisite for basic network access.
When this WOULD be correct
In a different question scenario where a network engineer is troubleshooting a link aggregation setup, a user PC connected to a switch port configured for EtherChannel might fail to communicate if EtherChannel is misconfigured or not properly negotiated, making this option correct.
- ✗
Trunk mode disables MAC address learning automatically
Why it's wrong here
Trunk mode does not disable MAC address learning; a switch in trunk mode still learns the source MAC addresses of incoming frames to build and update its CAM table, but it does so per VLAN using the 802.1Q tag. The difference is that an access port associates all learned MACs with a single VLAN, whereas a trunk port associates them with multiple VLANs. MAC learning is fundamental to Layer 2 switching and remains active regardless of the port mode.
When this WOULD be correct
In a scenario where a question states that a switch is configured to prevent MAC address learning for security reasons, and a user PC is connected to a trunk port, this option would be correct. The question would need to specify that MAC address learning is intentionally disabled on trunk ports.
- ✗
Trunk mode forces the switch to stop using IP addressing
Why it's wrong here
Trunk mode is a Layer 2 interface property that controls VLAN tagging on a link, and it has no effect on the switch's IP configuration or routing functions. The switch continues to use its management IP address, and any SVIs or routed interfaces remain operational independently of the switchport mode. Therefore, configuring a port as a trunk does not force the switch to stop using IP addressing.
When this WOULD be correct
In a scenario where a question states that a switch is configured to only allow access ports and is explicitly designed to prevent any IP addressing on trunk ports, option D could be correct. For example, if the question specifies that the switch's configuration is intended to isolate VLANs without IP communication, then trunk mode would indeed stop IP addressing.
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.
✓The port role is wrong because a normal PC-facing switchport should usually be an access port, not a trunkCorrect answer▾
Why this is correct
A normal PC expects to receive and send untagged Ethernet frames in a single VLAN, so the switchport facing it should be an access port assigned to one access VLAN. Configuring it as a trunk makes the switch tag frames with 802.1Q headers, which the PC's NIC typically cannot process, breaking connectivity. Thus the port role is the primary misconfiguration.
✗A user PC requires EtherChannel to functionWrong answer — click to see why▾
Why this is wrong here
A user PC does not require EtherChannel to function; EtherChannel is a method for bundling multiple physical links into a single logical link, which is not necessary for standard PC connectivity.
★ When this WOULD be the correct answer
In a different question scenario where a network engineer is troubleshooting a link aggregation setup, a user PC connected to a switch port configured for EtherChannel might fail to communicate if EtherChannel is misconfigured or not properly negotiated, making this option correct.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of network configurations, believing that advanced features like EtherChannel are necessary for all devices, especially in complex environments.
✗Trunk mode disables MAC address learning automaticallyWrong answer — click to see why▾
Why this is wrong here
Trunk mode does not disable MAC address learning; it actually allows the switch to learn MAC addresses from multiple VLANs. Therefore, a switch port configured as a trunk can still learn MAC addresses normally.
★ When this WOULD be the correct answer
In a scenario where a question states that a switch is configured to prevent MAC address learning for security reasons, and a user PC is connected to a trunk port, this option would be correct. The question would need to specify that MAC address learning is intentionally disabled on trunk ports.
Why candidates choose this
Candidates may confuse trunk mode with other configurations that limit MAC address learning, leading them to believe that trunking could inherently disable this feature. This misconception can arise from a lack of understanding of how VLANs and trunking work.
✗Trunk mode forces the switch to stop using IP addressingWrong answer — click to see why▾
Why this is wrong here
Trunk mode does not disable IP addressing; it allows multiple VLANs to be carried over a single link, and IP addressing is still applicable to the switch interfaces. Therefore, the user PC's inability to communicate is not due to trunk mode disabling IP addressing.
★ When this WOULD be the correct answer
In a scenario where a question states that a switch is configured to only allow access ports and is explicitly designed to prevent any IP addressing on trunk ports, option D could be correct. For example, if the question specifies that the switch's configuration is intended to isolate VLANs without IP communication, then trunk mode would indeed stop IP addressing.
Why candidates choose this
Candidates may confuse trunk mode with access mode capabilities and mistakenly believe that trunking limits IP addressing, especially if they have encountered scenarios where VLAN configurations affect communication. This misunderstanding can lead them to choose this option when they see 'trunk mode' mentioned.
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?”
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
MAC address
A MAC address is a unique hardware identifier assigned to a network interface card that allows devices to communicate on a local network.
Key term
Access port
An access port is a switch port that connects to a single end device, like a computer or printer, and carries traffic for only one VLAN.
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JA
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.