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Windows Repair Lab: sfc, DISM and chkdsk
Repair an unstable PC with built-in tools: end a runaway process, fix system files with sfc and DISM, check the disk and refresh policy.
Last updated
Windows command line · Intermediate · About 12 minutes
The scenario
A designer’s PC has been crashing since an update failed halfway. Apps close without warning, the fans run flat out, and a policy change IT made yesterday hasn’t reached it.
You have an administrator Command Prompt. Use the tools Windows ships with, in the order a technician would.
A practice Windows Command Prompt that runs in your browser. It understands real commands, and nothing you type can break anything.
Your tasks
0 of 5 doneList the running processes and find the one using the most memory. (not done yet)
End that process. (not done yet)
Scan and repair the system files. The first scan can’t fix everything: repair the Windows image, then scan again. (not done yet)
Check drive C: for file system errors and schedule the repair. (not done yet)
Refresh Group Policy so yesterday’s change applies. (not done yet)
Administrator: Command PromptPractice terminal · simulated
Practice Command Prompt: real commands on a simulated Windows PC. Type help to see what it knows.
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About this lab
What you’ll practice, and where it’s tested
What you’ll practice
- Finding a process with tasklist and ending it with taskkill
- Scanning system files with sfc /scannow
- Repairing the Windows image with DISM when sfc can’t
- Checking a disk with chkdsk
- Refreshing Group Policy with gpupdate
Exams it helps with
- CompTIA A+ Core 2Domain: Software Troubleshooting
- CompTIA A+ Core 2Domain: Operating Systems
Free performance-based questions: A+ Core 2
Walkthrough
One way to complete the lab, with the reason for each step. Try it yourself first.
Show the worked solution
- 1Find the process using the memory.
tasklist - 2End it.
taskkill /IM updater.exe /F - 3Scan the system files: some can’t be repaired.
sfc /scannow - 4Repair the image those files are restored from.
DISM /Online /Cleanup-Image /RestoreHealth - 5Scan again: this time the files are repaired.
sfc /scannow - 6Check the disk and schedule the fix.
chkdsk C: /f - 7Refresh policy.
gpupdate /force
Guide
How to get the most from a lab
Type the commands yourself
Typing a command, getting it wrong and fixing it is what makes it stick. Use the hints when you’re stuck, not before.
Check the walkthrough afterwards
Every lab has a worked solution with the reason for each step. Read it even when you finished: there is often a shorter way.
Do it again from memory
Reset the lab a day later and do it without hints. If you can, you know it. If you can’t, you’ve found what to study.
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FAQs
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Is this a real Windows PC?
No. It’s a practice Command Prompt that runs in your browser. It understands the real commands the lab needs and answers the way Windows would. It isn’t a full operating system: nothing is installed, and nothing you type can break anything.
Which commands does the practice Command Prompt understand?
The ones on the A+ objectives and a technician’s daily list: ipconfig, ping, tracert, nslookup, netstat, net user, net localgroup, tasklist, taskkill, sfc, DISM, chkdsk, gpupdate, dir, cd, md, copy, move and del. Type help for the full list. PowerShell cmdlets aren’t included.
Which exams does this lab help with?
It practices skills from CompTIA A+ Core 2 (Software Troubleshooting) and CompTIA A+ Core 2 (Operating Systems).
Do I need an account?
No. The labs run in your browser and nothing is saved. Sign up only if you want OpenpassAI’s full labs and progress tracking.
