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CompTIA A+ Operating Systems and Troubleshooting

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Question 1

The Windows Registry is a hierarchical database that stores configuration settings for the OS, hardware, applications, and user preferences.

Answer choices

  • A. True (Correct)

  • B. False

Explanation

The Windows Registry is organized into hives: HKEY_LOCAL_MACHINE (HKLM) — hardware and system-wide settings; HKEY_CURRENT_USER (HKCU) — current user settings; HKEY_USERS (HKU) — all user profiles; HKEY_CLASSES_ROOT (HKCR) — file associations and COM objects; HKEY_CURRENT_CONFIG (HKCC) — current hardware profile. The registry is edited with regedit.exe. Corruption can cause serious system issues. Technicians should always back up the registry before editing.

Question 2

A macOS user reports their Mac runs slowly after upgrading to the latest macOS version. Activity Monitor shows kernel_task consuming 100%+ of CPU. What is the MOST accurate explanation?

Answer choices

  • A. The Mac has a virus infecting the kernel process

  • B. kernel_task is artificially throttling CPU performance to manage thermal output (Correct)

  • C. The upgrade corrupted the kernel and the OS must be reinstalled

  • D. kernel_task always runs at 100% CPU on modern Macs during boot

Explanation

kernel_task in macOS is intentionally designed to consume high CPU percentages when the CPU is running hot. By occupying CPU cycles, it prevents user applications from using the CPU, which reduces heat generation — an intentional thermal management strategy by Apple. This is not a bug or malware. Common trigger: using USB-C/Thunderbolt ports on the left side of MacBook Pros (left-side thermal zone). Solutions: use right-side USB-C ports, ensure ventilation, or clean vents. Resetting SMC (System Management Controller) may also help if temperatures seem incorrect.

Question 3

Place the following steps in the correct order for the CompTIA A+ troubleshooting methodology:

1. Document findings, actions, and outcomes

2. Identify the problem (gather information, question the user)

3. Implement the solution or escalate

4. Establish a theory of probable cause

5. Verify full system functionality and apply preventive measures

6. Test the theory to determine the cause

7. Establish a plan of action to resolve the problem

Answer choices

  • A. Document findings, actions, and outcomes

  • B. Identify the problem (gather information, question the user)

  • C. Implement the solution or escalate

  • D. Establish a theory of probable cause

  • E. Verify full system functionality and apply preventive measures

  • F. Test the theory to determine the cause

  • G. Establish a plan of action to resolve the problem

Explanation

CompTIA A+ defines a 6-step troubleshooting process: (1) Identify the problem — question users, review symptoms, check recent changes, back up data; (2) Establish a theory of probable cause — consider multiple theories starting with most obvious; (3) Test the theory — if confirmed, determine resolution; if not, re-theorize or escalate; (4) Establish a plan of action — identify steps and their impact; (5) Implement the solution or escalate; (6) Verify full functionality; (7) Document everything. Documentation is always last.

Question 4

What is the purpose of the Windows command `ipconfig /flushdns`?

Answer choices

  • A. Releases and renews the DHCP IP address lease

  • B. Clears the local DNS resolver cache stored on the computer (Correct)

  • C. Flushes the TCP connection table

  • D. Resets the Windows Firewall DNS rules

Explanation

The DNS resolver cache stores recently resolved DNS lookups to speed up subsequent requests. If a website's IP address changes but the old record is still cached, users may be unable to reach the new address. `ipconfig /flushdns` clears this cache, forcing fresh DNS lookups. `ipconfig /release` releases the DHCP lease; `ipconfig /renew` requests a new DHCP lease. `ipconfig /displaydns` shows the current cache contents. This is a common first step when troubleshooting "site not found" errors after a DNS change.

Question 5

A technician discovers a Windows 10 workstation is infected with ransomware that has encrypted user files. The computer is still running. What should the technician do FIRST?

Answer choices

  • A. Run antivirus software to remove the ransomware

  • B. Pay the ransom to get the decryption key

  • C. Immediately disconnect the computer from the network to prevent spread (Correct)

  • D. Restore files from backup before removing the malware

Explanation

Ransomware is actively dangerous while running — it may still be encrypting files and could spread laterally to network shares, other computers, and backups connected to the network. The FIRST action is always containment: physically unplug the network cable and disable Wi-Fi. After isolation: (1) Identify the ransomware variant; (2) Check for available decryptors (nomoreransom.org); (3) Do NOT pay the ransom (no guarantee of key, funds criminal activity); (4) Restore from clean offline backups; (5) Rebuild the system. Never restore from backup while malware is active — it will re-encrypt restored files.