220-1101 Hardware and Network Troubleshooting Practice Question
A technician is troubleshooting a desktop computer running Windows 10 that has no network connectivity. The computer is connected via an Ethernet cable to a managed switch. The technician observes that the link light on the network interface card (NIC) is off, but the link light on the switch port is solid green. The technician tests the Ethernet cable with a cable tester and it passes. Connecting a different laptop to the same cable and switch port results in a successful connection. The technician boots the problematic computer from a Linux live USB drive and finds that the NIC link light comes on and the computer can access the network normally. After rebooting back into Windows, the NIC link light is off again and there is no connectivity. Which of the following is the MOST likely cause of this issue?
⚠ Common exam trap
The trap here is that candidates see the link light off and assume a hardware fault, but the key clue is the NIC works under Linux, which shifts the cause to a software/driver issue in Windows.
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 Windows NIC driver is corrupted or incompatible.
The NIC works under Linux but fails under Windows, which isolates the issue to the Windows software environment. A corrupted or incompatible NIC driver can prevent the OS from initializing the hardware, causing the link light to remain off and no connectivity. Since the hardware passes a cable test and works with another OS, the driver is the most likely cause.
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 NIC is physically faulty.
Why it's wrong here
A physical NIC fault would prevent link establishment and packet transmission at the hardware level, regardless of the operating system. Because the same adapter successfully operates under a Linux boot environment, the NIC's PHY, MAC, and PCIe/on-board interface are demonstrably functional. Windows cannot produce a hardware fault that Linux ignores, so this explanation is ruled out.
- ✗
The switch port is configured with port security.
Why it's wrong here
Switch port security, such as 802.1X or MAC address lockdown, would block or restrict the specific connected device, typically leaving the link light up but passing no traffic for that MAC. If the port were the cause, a different device on that port would also fail, and a Linux boot on the same PC would not restore connectivity. Since both those situations show full functionality, the switch port's security settings are not implicated.
- ✓
The Windows NIC driver is corrupted or incompatible.
Why this is correct
In Windows, the NIC driver is the kernel-mode component that communicates with the hardware through the NDIS/miniport interface. A corrupted, outdated, or incompatible driver can cause the OS to report the device as disabled (e.g., Device Manager error 10/56), fail to assign a valid IP, or simply not create a usable network interface. Because the identical hardware works under Linux, the fault is isolated to the Windows driver stack, making a driver-level issue the most plausible cause.
- ✗
The Ethernet cable is not properly seated.
Why it's wrong here
A poorly seated Ethernet cable generally produces an intermittent or absent link at Layer 1, with symptoms like link flap or excessive CRC errors that are independent of the operating system. The cable passes a certified tester, works with another device, and also works when the same PC is booted to Linux. These observations confirm that the physical cable and its connectors are sound, so a seating problem cannot explain the Windows-only failure.
Go deeper
Related to this question
Learn chapter
Laptop Hardware and Components
Key term
Network Interface Card
A Network Interface Card (NIC) is a hardware component that allows a computer or device to connect to a network and communicate with other devices.
Key term
Universal Serial Bus
A Universal Serial Bus (USB) is a standard interface that allows you to connect devices like keyboards, mice, storage drives, and printers to a computer for data transfer and power delivery.
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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.