220-1101 Mobile Devices Practice Question
A user reports that their Android smartphone's touchscreen is unresponsive in a narrow vertical strip near the left edge of the display. The rest of the screen responds normally to touch. The phone has not been dropped or exposed to moisture, and it functions otherwise normally. Which of the following is the MOST likely cause of this issue?
⚠ Common exam trap
Watch out — candidates often confuse digitizer and LCD panel failures, assuming any screen issue must be the LCD, when in fact touch input and display output are handled by separate components.
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
✓
Digitizer malfunction
The touchscreen digitizer is the layer responsible for detecting touch input. A narrow vertical strip of unresponsiveness, without any physical damage or other display issues, is a classic symptom of a failing or damaged digitizer, not the LCD panel. The LCD panel only handles image display, which is reported as normal.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Digitizer malfunction
Why this is correct
The digitizer is a separate touch-sensitive layer consisting of a grid of transparent conductive traces. When one of these traces breaks — often from a drop or repeated flexing — it leaves a continuous dead band where touches are not detected, while the rest of the grid continues to work normally. This matches the described symptom of a single unresponsive strip and is a classic hardware failure mode for capacitive touchscreens.
- ✗
LCD panel damage
Why it's wrong here
The LCD panel is responsible for producing the image; damage to it shows as visual artifacts such as cracks, black spots, color bleeding, or lines on the display. Touch detection is performed by the digitizer layer, which sits above the LCD, so LCD damage alone does not cause touch unresponsiveness unless the impact also breaks the overlying digitizer. In this case, the user's touchscreen is unresponsive but the 'screen' likely appears intact, ruling out LCD damage as the primary cause.
When this WOULD be correct
A user reports a cracked screen with a large black area and no touch response in that region, but the phone still powers on. This would indicate LCD panel damage affecting both display and touch in the damaged area.
- ✗
Software calibration issue
Why it's wrong here
Touch calibration maps the analog signals from the digitizer to exact on-screen coordinates. A calibration fault is rarely limited to a narrow strip; it typically produces global symptoms like cursor offset, erratic jumps, or complete touch failure across the whole display. Additionally, modern capacitive screens self-calibrate automatically and do not drift with age, so a persistent dead zone is far more consistent with physical damage than with software calibration.
When this WOULD be correct
A user reports that the touchscreen is misaligned or inaccurate across the entire display, and the issue persists after a reboot. This would indicate a software calibration problem, often resolved by recalibrating the touch input settings.
- ✗
Battery swelling
Why it's wrong here
Battery swelling creates mechanical pressure from behind the display assembly. That pressure can lift the screen, create visible bulging along the edges, or cause intermittent ghost touches and distorted colors, but it cannot selectively isolate a thin strip of touch sensors. Since the digitizer's traces are spread uniformly across a plane, a swollen battery would affect either a broad area or become an all-or-nothing failure, not a clean, stationary dead band.
When this WOULD be correct
A question describing a phone with a bulging back cover, screen lifting, or overall touchscreen unresponsiveness (especially after the device has been charging or exposed to heat) would point to battery swelling as the cause.
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 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓Digitizer malfunctionCorrect answer▾
Why this is correct
The digitizer is a separate touch-sensitive layer consisting of a grid of transparent conductive traces. When one of these traces breaks — often from a drop or repeated flexing — it leaves a continuous dead band where touches are not detected, while the rest of the grid continues to work normally. This matches the described symptom of a single unresponsive strip and is a classic hardware failure mode for capacitive touchscreens.
✗LCD panel damageWrong answer — click to see why▾
Why this is wrong here
LCD panel damage typically causes visual defects like discoloration, dead pixels, or black spots, not localized touch unresponsiveness. The touchscreen still works except for a narrow strip, indicating a digitizer issue, not the display panel.
★ When this WOULD be the correct answer
A user reports a cracked screen with a large black area and no touch response in that region, but the phone still powers on. This would indicate LCD panel damage affecting both display and touch in the damaged area.
Why candidates choose this
Candidates may confuse the digitizer (touch layer) with the LCD panel, assuming any screen issue is due to panel damage, especially when the problem is localized to a specific area.
✗Software calibration issueWrong answer — click to see why▾
Why this is wrong here
A software calibration issue would affect the entire screen or specific apps, not a narrow vertical strip. The localized nature of the problem points to a hardware digitizer failure.
★ When this WOULD be the correct answer
A user reports that the touchscreen is misaligned or inaccurate across the entire display, and the issue persists after a reboot. This would indicate a software calibration problem, often resolved by recalibrating the touch input settings.
Why candidates choose this
Candidates may think touchscreen issues can be fixed by software adjustments, overlooking that hardware digitizer problems often present as localized dead zones.
✗Battery swellingWrong answer — click to see why▾
Why this is wrong here
Battery swelling typically causes physical deformation of the phone case or screen, not a narrow vertical strip of unresponsiveness. The rest of the screen works fine, and there is no mention of bulging or other pressure symptoms.
★ When this WOULD be the correct answer
A question describing a phone with a bulging back cover, screen lifting, or overall touchscreen unresponsiveness (especially after the device has been charging or exposed to heat) would point to battery swelling as the cause.
Why candidates choose this
Candidates may associate any touchscreen issue with internal pressure or damage, and battery swelling is a known cause of display problems, but they overlook the specific pattern of a narrow strip, which is classic for digitizer failure.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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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.