220-1101 Networking Practice Question
A workstation is connected to a managed switch. It obtains a valid IP address (192.168.10.50) from the DHCP server, but it cannot ping the default gateway (192.168.10.1). The link light on both the workstation NIC and the switch port are solid green. Other workstations on the same switch CAN ping the default gateway successfully. The technician accesses the switch management interface and finds that the workstation's port is configured as an access port on VLAN 10. The default gateway is located on VLAN 20. An inter-VLAN router is configured but not explicitly allowing VLAN 10 access to VLAN 20. Which of the following is the MOST likely cause of the problem?
⚠ Common exam trap
The 220-1101 exam often tests the misconception that a valid IP address and solid link lights guarantee full connectivity, when in fact VLAN misconfiguration at the switch port prevents Layer 3 communication even within the same IP subnet.
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 switch port is assigned to VLAN 10, while the default gateway exists on VLAN 20, preventing connectivity without proper inter-VLAN routing.
The workstation is on VLAN 10, but the default gateway is on VLAN 20. Without inter-VLAN routing explicitly allowing traffic between VLAN 10 and VLAN 20, the workstation cannot reach the gateway, even though it has a valid IP address from the correct subnet. The link lights are solid green, indicating Layer 1 connectivity is fine, and other workstations on the same switch can ping the gateway, confirming the switch and gateway are operational.
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 workstation's IP address is from a different subnet than the default gateway.
Why it's wrong here
This is incorrect because the workstation's IPv4 address (192.168.10.50) and the default gateway address (192.168.10.1) both fall within the 192.168.10.0/24 subnet when using a /24 mask. A subnet mismatch would require the address and gateway to have different network IDs, which is not the case here. While VLAN segmentation can prevent traffic even within the same IP subnet, the specific claim about a subnet mismatch is factually wrong. The failure is due to Layer 2 isolation, not Layer 3 addressing.
- ✓
The switch port is assigned to VLAN 10, while the default gateway exists on VLAN 20, preventing connectivity without proper inter-VLAN routing.
Why this is correct
The port's VLAN assignment restricts the workstation to communicate only within VLAN 10. The gateway is on a different VLAN, so inter-VLAN routing must be enabled to allow access. The current configuration lacks this, causing the failure.
- ✗
The workstation's network interface card (NIC) is malfunctioning.
Why it's wrong here
This is incorrect because a malfunctioning NIC would not successfully complete DHCP address acquisition or maintain link on the switch port. The workstation obtained a valid IP address, which requires the NIC to send DHCPDISCOVER and receive DHCPOFFER over an active link; this proves Layer 1 and Layer 2 functionality. Additionally, if the NIC were faulty, the switch port would typically show no link or constant CRC errors, and the workstation would not appear in the ARP table of the gateway. The issue is specific to VLAN assignment, not hardware failure.
- ✗
The DHCP server provided an incorrect default gateway address.
Why it's wrong here
This is not the cause because DHCP delivered the correct default gateway address—192.168.10.1—which matches the subnet's expected gateway. If the DHCP server had handed out a wrong gateway, the workstation's packets would be sent to an unreachable next hop and would fail to leave the subnet, but here the gateway address is valid on the network; the problem is that the gateway interface resides on VLAN 20, not VLAN 10. Even with a correct IP, the workstation's untagged frames stay in VLAN 10, so the gateway cannot receive them without an inter-VLAN routing configuration. Therefore, the DHCP assignment is correct, but the VLAN topology blocks reachability.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA 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 220-1101 exam.