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75 multiple-choice questions and 29 flashcards on Core 1 — Hardware and Network Troubleshooting, about 14% of the CompTIA A+ bank. Every one carries a written rationale.
Core 1 — Hardware and Network Troubleshooting is one of 9 chapters in CoStudy's CompTIA A+ bank, and it holds 75 of the bank's 540 multiple-choice questions — roughly 14% 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 user complains that an external drive is recognized but transfers files far slower than expected. The drive works at full speed on another machine. Which check is MOST likely to explain the difference?
Answer: C — The port in use is an older, lower-bandwidth USB port
C) Correct — the same drive performing correctly elsewhere points to the host port, and connecting to a legacy lower-speed USB port throttles throughput while still enumerating the device. A) File system choice affects overhead modestly but would follow the drive to the other machine. B) Insufficient bus power causes dropouts or non-detection, not steady slow transfers. D) Media degradation would slow the drive on every host, not just one.
A user's PC gets an IP via DHCP but cannot resolve hostnames. Pinging a public IP (e.g., 8.8.8.8) works. The MOST likely cause:
Answer: B — The DNS server is unreachable or misconfigured
Successfully pinging a public address proves Layer 3 connectivity works, so the failure is name resolution and points at DNS. A gateway fault would have blocked the ping. A wrong mask or a disconnected cable would break all traffic, not just lookups.
A laptop's screen is dim even at max brightness setting. The MOST likely component to test/replace:
Answer: C — The backlight or its driver circuit on the panel
A dim screen at maximum brightness points to the backlight or its driver circuit; shine a flashlight at the panel and a faint image confirms the panel itself is fine. A and B blame graphics hardware, which would distort or blank the image rather than dim it. D is unrelated to display output.
After adding a second graphics card, a system powers on for one second and immediately powers off, repeatedly. All connectors are seated. What is the MOST probable cause?
Answer: C — The power supply cannot deliver the required load and is protecting
C) Correct — an instant power-on then power-off loop after adding a high-draw device points to overcurrent protection in an undersized supply. A) Drivers cannot matter when the system never reaches the operating system. B) A wrong monitor input gives no display but the system stays powered on. D) A disabled slot would simply ignore the card rather than cut system power.
Users on a VoIP system report choppy audio and words arriving out of order during busy periods, while file transfers remain acceptable. Which cause is MOST consistent?
Answer: B — Variable delay and packet loss under congestion are affecting voice
B) Correct — jitter and loss during congestion degrade real-time voice long before they visibly affect retransmitted bulk transfers, which is why voice needs prioritization. A) A codec mismatch usually produces no audio or consistently poor audio rather than a load-dependent pattern. C) Slow DNS delays call setup and lookups, not the quality of an established stream. D) Duplex mismatch causes constant errors and slowness in all traffic, not just at peak.
A workstation cannot reach the internet but can ping the default gateway. What is the MOST likely cause?
Answer: B — The configured DNS server is unreachable or wrong
B is right because a successful gateway ping proves link, addressing, and local routing all work, so the remaining common failure for named internet sites is name resolution. A, C, and D are all ruled out by that same successful ping, since none of them would allow any traffic at all. E is a catch-all that does not explain why local traffic still succeeds. Confirm by pinging an external IP address directly.
A traveling employee's phone shows no service after arriving in another country, though Wi-Fi calling works. Which item should the technician verify FIRST?
Answer: B — Whether the eSIM profile and roaming settings are active
B) Correct — loss of cellular service on arrival abroad, with Wi-Fi functioning, points to the carrier profile or roaming permission, which on eSIM devices is a settings and provisioning matter. A) Full storage slows the device but does not remove cellular registration. C) A screen protector does not sit over cellular antennas or block registration. D) A pending update rarely disables cellular service outright and would affect the home country too.
A BSOD shows 'PAGE_FAULT_IN_NONPAGED_AREA' that recurs at random. The BEST diagnostic step is:
Answer: C — Run a memory diagnostic such as MemTest86 on the RAM
This STOP code usually means faulty RAM or a driver touching bad memory, so a memory diagnostic isolates it cheaply. A reinstall is premature, a motherboard swap is an expensive guess, and a BIOS update is not the first diagnostic move.
An HDD is making a regular clicking sound and Windows reports SMART errors. The BEST action is:
Answer: D — Back up the data immediately and replace the failing drive
Regular clicking together with SMART errors signals imminent mechanical failure, so copy the data off first and then replace the drive. Continuing to use it risks total loss, and reformatting or defragmenting stresses a dying drive without fixing anything.
A user's monitor displays a very dim image that becomes visible when a bright flashlight is shined at the panel. What is the MOST likely faulty component?
Answer: C — The backlight or its inverter in the display
C) Correct — a readable image under external light means the panel and signal are fine but the illumination source has failed. A) A failed adapter produces no image or artifacts, not a correctly rendered dark one. B) Cable faults cause flicker, color loss, or no signal, not uniform dimming with intact content. D) Driver problems affect resolution and color depth, not panel illumination.
4 cards from the 29 in this chapter.
How do you diagnose intermittent system crashes?
Check temperatures, run memory test (MemTest86), test storage (SMART), update drivers, check Event Viewer, swap PSU, reseat components.
What is the standard A+ troubleshooting methodology?
1) Identify the problem 2) Establish a theory of probable cause 3) Test the theory 4) Establish a plan of action 5) Implement and verify 6) Document findings.
What are the current CompTIA A+ exam codes, when did they launch, and what is the format of each exam?
Core 1 is 220-1201 and Core 2 is 220-1202, launched March 25, 2025, replacing the retired 220-1101 and 220-1102. Each exam has a maximum of 90 questions in 90 minutes, mixing single and multiple response multiple choice with performance-based questions. Both cores are required and may be taken in either order.
What is the most common cause of laptop charging issues?
Failing AC adapter, damaged DC jack, charging port lint/debris, swollen battery. Test with known-good adapter and try the device with battery removed.
These are a sample. The full Core 1 — Hardware and Network Troubleshooting chapter runs 104 items with per-chapter progress tracking, on the web and in the iOS app.