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35 multiple-choice questions and 19 flashcards on Core 1 — Mobile Devices, about 6% of the CompTIA A+ bank. Every one carries a written rationale.
Core 1 — Mobile Devices is one of 9 chapters in CoStudy's CompTIA A+ bank, and it holds 35 of the bank's 540 multiple-choice questions — roughly 6% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
10 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
A technician needs a phone to make a contactless payment at a terminal by holding the handset within a few centimeters. Which technology is in use?
Answer: B — Near-field communication between phone and reader
A) Personal area wireless links reach several meters and require an explicit pairing exchange, which tap payments do not. B) Correct — the few-centimeter range and tap-to-transact behavior are the defining characteristics of near-field communication. C) Infrared needs unobstructed line of sight and is not used by payment terminals. D) Beacons advertise presence to apps one way and cannot carry a payment transaction.
A designer complains that two identical external monitors show the same photo at noticeably different sizes, though both run at their native resolution. Which factor BEST explains the difference?
Answer: C — The monitors have different pixel densities
A) Refresh rate changes motion smoothness, not the size of a static image. B) Backlight technology such as Mini LED changes brightness and contrast behavior, not scale. C) Correct — at native resolution, apparent size is governed by pixels per inch; two panels with different densities render the same image at different physical sizes. D) Color depth affects gradient and banding quality, leaving geometry untouched.
A user connects a laptop to a docking station and gets network, keyboard and mouse, but only one of two attached monitors lights up. Which is the MOST likely cause?
Answer: D — The laptop's port does not support the dock's display stream count
A) A failed dock would generally take down the network and input devices too, which are working. B) Insufficient wattage shows up as slow or absent charging, not as a selective loss of one display. C) An unsupported refresh rate usually produces an out-of-range message rather than a completely dark panel with everything else working. D) Correct — the number of independent display streams a host port can drive is a hard limit; other dock functions work fine while the extra monitor simply gets no stream.
An Android phone has MDM enrolled by the employer. Which is TRUE about the MDM's capabilities?
Answer: A — Enforcing passcode policy, pushing apps, wiping corporate data
MDM enforces passcode policy, deploys apps, remote-wipes corporate data, and reports posture. B overstates its reach — it cannot generally intercept SMS and calls. C is wrong because MDM sets biometric policy rather than bypassing it. D confuses management enrollment with rooting the device.
Which statement BEST describes why many current laptops offer no user-upgradable system memory?
Answer: B — Memory modules are soldered to the board
A) The memory controller did move on-die, but that is a performance and architecture change and has no bearing on whether modules are replaceable. B) Correct — soldered-down memory is the physical reason there is nothing to remove or add; the modules are permanent parts of the board. C) Firmware pairing of memory is not how laptops work; it confuses memory with some paired security components. D) Many such laptops still have access panels for storage and the battery, so panel design is not the cause.
A laptop runs fine on AC power but shuts down instantly when the adapter is unplugged, even though the OS reports the battery at 82 percent. Which explanation is MOST likely?
Answer: C — The battery cells are degraded and cannot deliver load current
A) An undersized adapter causes throttling or slow charging while on AC, the opposite of this symptom. B) A faulty power button would drop the system regardless of power source, not only on battery. C) Correct — a worn pack can hold a reported state of charge yet collapse under load, which produces an instant shutdown the moment AC is removed. D) Power management settings change sleep and throttling behavior, but they do not cause an immediate loss of power.
An Android user wants to use their phone as a USB host to a flash drive. This requires:
Answer: A — USB OTG support plus an OTG cable or adapter
USB OTG lets the phone act as host so a flash drive can be attached, usually with an OTG adapter. MTP runs the opposite direction, exposing the phone as storage to a PC. ADB is a developer channel, and root access is not needed.
A technician is asked to install additional storage in an ultrabook that already has one occupied M.2 socket and no empty sockets. Which approach BEST meets the need without modifying the chassis?
Answer: D — Clone to a higher-capacity module and reuse the single socket
A) Partitioning divides existing space and adds no capacity at all, a common misconception among users. B) Optical bays are absent from ultrabooks, so the caddy trick belongs to older thick chassis. C) Ultrabooks have no spare SATA data header; this is the answer to a desktop question. D) Correct — with one socket and no expansion bays, imaging onto a larger module is the only internal path to more capacity.
Employees in the field must reach an internal application that is only published on the corporate network. Which mobile configuration BEST supports this over cellular?
Answer: D — A managed VPN profile to the corporate network
A) A hotspot only shares internet access and does not place the device inside the corporate network. B) Cached data goes stale and offers no path to a live server-side application. C) A saved wireless profile is useless out of range of the corporate access points. D) Correct — a VPN profile creates an encrypted tunnel from the cellular-connected device into the corporate network where the application lives.
After a laptop screen replacement the display works but the built-in webcam and microphone are dead. Which is the MOST likely cause?
Answer: D — The camera and microphone cable was not reconnected in the lid
A) A closed shutter blocks the camera image but would not silence the microphone. B) Pixel density affects image sharpness on the panel and has nothing to do with camera or audio capture. C) A repair does not uninstall drivers, and a driver problem would not typically take out both devices simultaneously. D) Correct — the camera and microphone ride in the lid on their own harness, and losing both at once right after a lid-side repair points squarely at an unconnected cable.
4 cards from the 19 in this chapter.
What is the difference between Bluetooth Classic and BLE?
Classic: continuous data streaming (audio, headsets). BLE (Low Energy): low-power, short bursts of data — sensors, wearables, beacons.
What is the difference between mobile hotspot and USB tethering, and which one is generally preferred for battery life?
A mobile hotspot shares the phone's cellular data by broadcasting a Wi-Fi network that multiple clients can join. USB tethering shares the same connection over a cable to one host and simultaneously charges the phone, so it is preferred when battery life or Wi-Fi congestion is a concern.
What is MDM and what does it do?
Mobile Device Management — centrally configure, secure, monitor, and remotely wipe devices. Common in enterprise BYOD/COBO deployments.
What is NFC and what is it used for on mobile devices?
Near-Field Communication — short-range (≤4 cm) wireless. Used for tap-to-pay, device pairing, and ticket/transit applications.
These are a sample. The full Core 1 — Mobile Devices chapter runs 54 items with per-chapter progress tracking, on the web and in the iOS app.