220-1101 Question 419
Single answerDead pixelsA user reports that a new laptop has a tiny black dot near the center of the screen that remains visible on a white background and does not move when windows are dragged. You connect the laptop to an external monitor, and the image appears normal there. The laptop's display cable is firmly connected, and the dot is still present after restarting the system and loading the BIOS screen. What is the MOST likely cause of the problem?
- A
A dead pixel on the laptop's LCD panel
- B
A corrupted graphics driver causing a display artifact
- C
A loose display cable between the motherboard and LCD
- D
Burn-in from a static image left on the screen
Show answer and explanation
Correct answer: A
Explanation
The best answer is a dead pixel on the laptop's LCD panel. In troubleshooting display issues, technicians isolate the fault by comparing the built-in display with an external monitor and by checking whether the symptom appears before the operating system loads. Since the artifact is present in BIOS and only on the laptop panel, the GPU and drivers are unlikely causes. A dead pixel is a hardware defect in the LCD panel itself. CompTIA A+ Core 1 objectives commonly expect candidates to distinguish panel defects such as dead pixels from issues caused by cables, drivers, or video cards. In practice, the next step would be to review the manufacturer's dead-pixel policy and warranty terms, because replacement eligibility often depends on the number and location of defective pixels.
- A. Correct.
This is correct. A dead pixel is a failed pixel that stays permanently off, often appearing as a black dot regardless of what is displayed. Because the issue remains visible in the BIOS and does not appear on an external monitor, the problem is isolated to the laptop's built-in LCD panel rather than the GPU, operating system, or driver stack.
- B. Incorrect.
This is incorrect. A graphics driver problem would typically affect the image only after the operating system loads, not in the BIOS. In many cases, a driver-related artifact would also be visible on an external monitor because the GPU output is shared. The fact that the external display is normal and the dot appears before the OS loads points away from a driver issue.
- C. Incorrect.
This is incorrect. A loose display cable is more likely to cause flickering, intermittent image loss, color distortion, lines, or a completely blank display rather than a single fixed black dot. Since the dot is stable and isolated to one tiny area, a panel defect is the more likely explanation.
- D. Incorrect.
This is incorrect. Burn-in is more associated with certain display technologies and usually appears as a faint ghost image of previous content, not as a single, permanently black dot. A lone black dot that persists across all content is much more consistent with a dead pixel than image retention or burn-in.