10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The CST exam has 80 questions and runs 2 hours.
These 10 free CST questions are organized by exam domain, so you can see how each part of the Computer Service Technician blueprint is tested. Reveal the answer and explanation under each question.
A coworker has collapsed with a hand still touching an exposed mains terminal. Another employee is calling emergency services. A clearly identified supply disconnect is safely reachable without approaching the casualty. What must happen before anyone touches the coworker?
Correct answer: D - Open the disconnect to isolate the electrical supply.
Four observations appear in an expansion-card service report. Which one requires correction because two devices are claiming an exclusive hardware resource?
Correct answer: C - Two legacy adapters use exclusive I/O ranges 0x300-0x31F and 0x310-0x32F.
A CPU heatsink was removed during a repair. After reassembly, the processor rapidly heats up under load and reports thermal throttling. The fan reaches full speed, but the heatsink shows little temperature rise. Opening the case makes no appreciable difference. Where should the technician focus the inspection?
Correct answer: C - CPU-to-heatsink contact and thermal compound.
An M.2 replacement SSD is not detected. It is fully seated in the 2280 mounting position, but its label identifies it as SATA. The laptop's service manual lists this socket as PCIe/NVMe-only. Select the change that resolves the mismatch.
Correct answer: D - Install an NVMe module of a supported physical size.
A 64-GB USB drive has 50 GB free, but copying a single 7-GB disk image to it fails; smaller files copy successfully. The FAT32 drive must remain writable from both Windows and macOS. The Mac's installed tools read NTFS but cannot write it. After preserving the existing files, which change meets these needs?
Correct answer: A - Reformat the drive as exFAT.
After several weeks without use, an inkjet printer produces missing horizontal lines. A nozzle check started from its control panel shows gaps in the black pattern; the paper path is clear and there is no fault message. What is the appropriate first maintenance step?
Correct answer: A - Run the printhead-cleaning routine, then repeat the nozzle check.
UPS label: 1,000 VA / 600 W. Measured steady load: 720 VA / 650 W. Status: overload. Which rating accounts for the overload indication?
Correct answer: B - The watt rating: 650 W exceeds the unit's 600-W capacity.
A laptop's battery drains during an 80-W workload while a USB-C dock supplies its specified 45 W. Data and video work normally. Under the same workload, the laptop charges when its approved 90-W adapter supplies power. Which remedy addresses the demonstrated limitation?
Correct answer: D - Use a compatible 90 W charging path.
A desktop develops intermittent crashes. Its board supports either memory slot for single-module operation. Two identically specified modules produce these preboot diagnostic results: Module A: fails in slot 1 and slot 2. Module B: passes in slot 1 and slot 2. Which component should the technician replace on this evidence?
Correct answer: B - Module A, followed by another diagnostic run.
A Windows 10 PC previously started through Windows Boot Manager in UEFI mode from a GPT disk. After a firmware update, it reports no bootable device. Firmware still detects the SSD, but its boot mode is now Legacy-only; the drive's partitions are unchanged. How can the technician restore the original startup path?
Correct answer: B - Restore UEFI boot and select Windows Boot Manager.
The CST exam also covers these domains. Drill them in the full free practice test:
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