CCNA Switching and Network Access Practice Question
A switchport is configured as an access port for VLAN 20, but users connected to it cannot reach the default gateway. The switch shows the interface as up/up. Which switch misconfiguration is the most likely cause?
⚠ Common exam trap
A common exam trap is assuming that an interface showing up/up means the port is fully functional and correctly forwarding traffic. Candidates may overlook the necessity of creating the VLAN in the switch’s VLAN database. Without VLAN 20 existing, the switch cannot forward traffic for that VLAN, even though the physical link is active. This leads to confusion because the interface status does not reflect VLAN misconfiguration, causing users to lose connectivity to the default gateway despite the port appearing operational.
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
✓
VLAN 20 has not been created on the switch
If the access port is assigned to VLAN 20 but VLAN 20 does not exist in the VLAN database, traffic is not placed into a usable VLAN and hosts lose connectivity. The port can still appear physically up while forwarding fails at Layer 2.
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 access port is missing a speed command
Why it's wrong here
The 'speed' command only configures the physical link speed (e.g., 100, 1000 Mbps) and does not affect VLAN membership or port activation. If the speed is not specified, the switch auto-negotiates with the connected device; a mismatched speed can cause link issues, but that is unrelated to the VLAN not existing. The port would still not forward packets for VLAN 20 if the VLAN is absent, regardless of the speed setting. Thus, this is a distractor that conflates Layer 1 configuration with Layer 2 VLAN requirements.
When this WOULD be correct
In a different scenario, if a question specified that a switchport is operational but experiencing performance issues or intermittent connectivity, and the configuration lacks a speed command, then this option could be correct as speed mismatches can cause such problems.
- ✓
VLAN 20 has not been created on the switch
Why this is correct
When a switchport is configured as an access port in a VLAN that does not exist in the switch's VLAN database, the port will not become active in that VLAN. The switch will not forward traffic for the nonexistent VLAN; the port typically remains in a down or inactive state until the VLAN is created. Creating the VLAN with 'vlan 20' in global configuration mode and assigning it a name is required before the access port can pass traffic for VLAN 20. Even though the port configuration may be accepted, the port will not operate correctly until the VLAN exists.
- ✗
The switch has not enabled VTP transparent mode
Why it's wrong here
The issue is not about VTP mode. VTP transparent mode only affects whether the switch advertises or learns VLAN information from other switches; it does not cause a locally configured access port to fail if the VLAN is absent. In transparent mode, the switch does not share VLAN database changes, but it still requires the VLAN to exist locally. Therefore, lacking VTP transparent mode is irrelevant to the port's inability to work; the VLAN must be created regardless of VTP mode.
When this WOULD be correct
In a scenario where a question asks about VLAN propagation issues in a network using VTP, and the context specifies that VLANs must be created on a VTP server for clients to access them, this option would be correct if the switch was not configured to propagate VLAN information properly.
- ✗
The port should use DTP desirable mode
Why it's wrong here
DTP (Dynamic Trunking Protocol) is used to negotiate trunking between switches, not to determine access port operation. An access port does not need DTP; in fact, access ports typically send DTP frames but are not used for trunk negotiation. Setting the port to 'dynamic desirable' would make it a trunk-capable port, not an access port, and would not resolve an issue where the VLAN itself is missing. The port's administrative mode as access is already correct; the problem is the nonexistent VLAN.
When this WOULD be correct
In a scenario where the question specifies that the switchport is intended to be a trunk port and needs to negotiate trunking with a connected device, selecting D would be correct if the port was incorrectly set to access mode instead of trunk mode using DTP.
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.
✓VLAN 20 has not been created on the switchCorrect answer▾
Why this is correct
When a switchport is configured as an access port in a VLAN that does not exist in the switch's VLAN database, the port will not become active in that VLAN. The switch will not forward traffic for the nonexistent VLAN; the port typically remains in a down or inactive state until the VLAN is created. Creating the VLAN with 'vlan 20' in global configuration mode and assigning it a name is required before the access port can pass traffic for VLAN 20. Even though the port configuration may be accepted, the port will not operate correctly until the VLAN exists.
✗The access port is missing a speed commandWrong answer — click to see why▾
Why this is wrong here
The speed command is used for setting the interface speed (e.g., 10/100/1000 Mbps) and does not affect VLAN membership or layer 3 reachability. A missing speed command would not prevent users from reaching the default gateway as long as the interface is up/up.
★ When this WOULD be the correct answer
In a different scenario, if a question specified that a switchport is operational but experiencing performance issues or intermittent connectivity, and the configuration lacks a speed command, then this option could be correct as speed mismatches can cause such problems.
Why candidates choose this
Students might think that a missing speed command could cause connectivity issues, but speed mismatches typically cause the interface to be down/down, not up/up. Since the interface is up/up, speed is not the issue.
✗The switch has not enabled VTP transparent modeWrong answer — click to see why▾
Why this is wrong here
VTP transparent mode is a VTP (VLAN Trunking Protocol) setting that allows a switch to forward VTP advertisements without participating in VLAN database synchronization. It is not required for basic VLAN operation; VLANs can be created locally regardless of VTP mode. The issue here is that VLAN 20 does not exist, not that VTP mode is incorrect.
★ When this WOULD be the correct answer
In a scenario where a question asks about VLAN propagation issues in a network using VTP, and the context specifies that VLANs must be created on a VTP server for clients to access them, this option would be correct if the switch was not configured to propagate VLAN information properly.
Why candidates choose this
Students may confuse VTP transparent mode with the requirement for VLANs to be propagated via VTP. However, in a network without VTP or with VTP transparent mode, VLANs must be created manually. The absence of VTP transparent mode does not prevent VLAN creation.
✗The port should use DTP desirable modeWrong answer — click to see why▾
Why this is wrong here
DTP (Dynamic Trunking Protocol) desirable mode is used to negotiate trunking on a port. An access port should not use DTP desirable mode; it should be configured as an access port with 'switchport mode access'. Using DTP desirable could cause the port to become a trunk, which would not allow the VLAN 20 traffic to be properly handled as access traffic.
★ When this WOULD be the correct answer
In a scenario where the question specifies that the switchport is intended to be a trunk port and needs to negotiate trunking with a connected device, selecting D would be correct if the port was incorrectly set to access mode instead of trunk mode using DTP.
Why candidates choose this
Students might think that DTP desirable helps with VLAN negotiation, but it is for trunking, not access VLAN assignment. The correct configuration for an access port is to set it to access mode, not to use DTP.
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
Go deeper
Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
Switch
A switch is a networking device that connects devices on a local area network and uses MAC addresses to forward data only to the intended recipient.
Key term
Default gateway
A default gateway is a network device, typically a router, that acts as the exit point for traffic from a local network to other networks, including the internet.
About these practice questions
Courseiva writes every 200-301 question from scratch — 1,389 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.