Device drivers are software that allow the operating system to communicate with hardware. CompTIA A+ 220-1102 tests driver installation, updates, rollback, and troubleshooting driver conflicts. Driver problems cause device failures, system instability, BSODs, and performance issues — knowing how to manage drivers is a daily technician skill.
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What drivers do: each hardware device (GPU, NIC, sound card, printer, USB device) needs a driver — software that translates OS commands into hardware-specific instructions. Without a driver: device doesn't work (Device Manager shows yellow warning or device is absent). With wrong driver: device may appear partially functional or cause instability.
Driver sources: Windows Update — automatically delivers drivers for most common devices (plug and play). Manufacturer website — provides the most current and feature-complete drivers (best for GPU, NIC, printers). Installation media (disc) — often outdated, download from web instead. Third-party driver update software — generally not recommended (can install wrong drivers). Always prefer manufacturer directly over generic Windows drivers for best performance.
Installing drivers: download the driver installer from the manufacturer. Run the installer — it typically installs the driver and management software. After reboot, verify the device appears in Device Manager without warnings. For GPU specifically: run DDU (Display Driver Uninstaller) in safe mode before switching GPU brands or performing clean driver installation.
Updating drivers: Windows Update (automatic) — convenient. Device Manager → right-click device → Update driver → Search automatically. Manufacturer download → install newer version. After Windows major update, some drivers may need reinstallation if the update replaced them with generic versions.
Device Manager: the primary tool for driver troubleshooting. Yellow exclamation (!) = driver error or conflict. Red X = device disabled. No icon = device not detected. Right-click device → Properties → Details tab → check Device status message. Right-click device → Update driver, Disable device, Uninstall device. View hidden devices: View → Show hidden devices.
Driver rollback: after a driver update causes problems, right-click device in Device Manager → Properties → Driver tab → Roll Back Driver (only available if a previous driver exists). This reverts to the prior driver version. Useful when Windows Update installs a problematic driver update that breaks functionality.
Signed vs unsigned drivers: signed drivers have a digital signature from Microsoft verifying they haven't been tampered with. Windows 64-bit requires signed drivers by default — installing an unsigned driver triggers a warning and may be blocked. Unsigned drivers can cause instability. To test with an unsigned driver: boot with driver signature enforcement disabled (advanced startup options).
BSOD from driver: Blue Screen with 'DRIVER_IRQL_NOT_LESS_OR_EQUAL', 'DRIVER_POWER_STATE_FAILURE', or similar stop codes indicate driver problems. Boot to safe mode (loads minimal drivers) to uninstall the problematic driver. Use Event Viewer to examine crash details. Windows creates a minidump file at each BSOD — analyze with WinDbg for the specific driver that caused the crash.
Updating all drivers to the latest version always improves system performance
Driver updates can introduce new bugs or regressions — 'if it's not broken, don't fix it' applies to drivers. Update drivers when: there's a specific bug fix you need, you're experiencing an existing problem the update addresses, or a security vulnerability is patched. Blindly updating all drivers can destabilize a working system. GPU drivers are the main exception — current GPU drivers often include performance improvements for recent games
These questions are representative of what you will see on A+ exams. The correct answer and explanation are shown immediately below each question.
After Windows Update ran overnight, a user's USB audio interface no longer works. Device Manager shows a yellow warning on the audio device. What is the best first action?
Explanation: Windows Update replaced the working audio driver with a generic or newer version that doesn't work correctly — a very common scenario. Roll Back Driver reverts to the previous known-working driver. In Device Manager: right-click the audio device → Properties → Driver tab → Roll Back Driver. If Roll Back Driver is grayed out, download and manually install the previous version from the manufacturer's website. Rolling back is the most targeted and least disruptive fix for a post-update device failure.
After uninstalling or rolling back a problematic driver, Windows Update may reinstall it automatically. To prevent this: Settings → System → Advanced System Settings → Hardware tab → Device Installation Settings → 'No (your device might not work as expected)' — this disables automatic driver installation via Windows Update. Alternatively, use the 'Show or hide updates' troubleshooter from Microsoft's website to specifically hide the problematic update from being installed. This is a temporary workaround until a fixed driver version is available from the manufacturer.
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