comptia-a-plus-core2/notes/OS-4-windows-command-line.md

OS-4: Windows Command Line

Status: not started

Domain:

• 1.0 Operating Systems

Objective alignment:

• 1.5 Windows command-line tools
• 1.7 Windows networking basics
• 3.1 Windows troubleshooting support

What You Need To Know

Core 2 command questions usually ask, "Which command would you use?"

Think in buckets:

• Navigation: move around files and folders.
• Network: check IP address, connectivity, DNS, routes, and connections.
• Disk/file repair: check file systems and system files.
• Identity/system info: computer name, signed-in user, Windows version.
• Group Policy: update or report applied policies.
• Help: find command syntax.

Some commands are safe to run anytime. Others can change disks or files, so use them carefully.

Memory Tricks

• ipconfig = IP configuration.
• ping = "Are you alive?"
• tracert = trace route.
• nslookup = name server lookup.
• netstat = network statistics.
• chkdsk = check disk.
• sfc = system file checker.
• gpupdate = Group Policy update.
• gpresult = Group Policy result.
• /? = "How do I use this?"

Commands To Enter

Enter these on Windows PowerShell or Command Prompt.

Navigation

dir

What it does:

• Lists files and folders in the current directory.
• Similar Linux command: ls.

cd

What it does:

• Shows or changes the current directory.
• cd .. moves up one folder.

mkdir test-folder

What it does:

• Creates a folder named test-folder.
• md does the same thing.

rmdir test-folder

What it does:

• Removes an empty folder.
• rd does the same thing.

Network

ipconfig

What it does:

• Shows IP address, subnet mask, and default gateway for network adapters.

ipconfig /all

What it does:

• Shows detailed adapter info, including MAC address, DNS servers, DHCP status, and lease details.

ping 127.0.0.1

What it does:

• Tests the local TCP/IP stack using the loopback address.
• If this fails, the local networking stack has a problem.

ping 8.8.8.8

What it does:

• Tests basic IP connectivity to an external address.
• If this works but names do not, suspect DNS.

nslookup example.com

What it does:

• Queries DNS for a hostname.
• Useful when websites fail by name but IP connectivity works.

tracert example.com

What it does:

• Shows the router hops toward a destination.
• Useful for finding where a path may stop.

pathping example.com

What it does:

• Combines route tracing with packet-loss statistics.
• Takes longer than tracert.

netstat -ano

What it does:

• Shows active connections and listening ports.
• -a shows all connections/listeners.
• -n keeps addresses numeric.
• -o shows process IDs.

Disk and File Repair

chkdsk

What it does:

• Checks the disk file system status.

chkdsk /f

What it does:

• Fixes logical file system errors.
• May need to run at startup if the drive is locked.

chkdsk /r

What it does:

• Looks for bad sectors and recovers readable information.
• Includes /f.
• Can take a long time.

sfc /scannow

What it does:

• Scans protected Windows system files and repairs them when possible.

Identity and System Info

hostname

What it does:

• Shows the computer name.

whoami

What it does:

• Shows the current user.

whoami /all

What it does:

• Shows current user, groups, privileges, and security identifier details.

winver

What it does:

• Opens the Windows version/build dialog.

Group Policy

gpupdate /force

What it does:

• Forces a Group Policy refresh.
• Most relevant on domain-joined business systems.

gpresult /r

What it does:

• Shows Resultant Set of Policy summary for the user/computer.
• Use it to verify what policies applied.

Help

ipconfig /?

What it does:

• Shows help and syntax for ipconfig.
• Most Windows commands support /?.

help dir

What it does:

• Shows help for the dir command.

Commands To Know But Treat Carefully

format

What it does:

• Formats a volume.
• Warning: this can erase data.

diskpart

What it does:

• Opens a powerful disk partitioning tool.
• Warning: incorrect commands can erase partitions or make a system unbootable.

robocopy

What it does:

• Copies files and folders robustly.
• Useful for backups and migrations.
• Be careful with mirror options because they can delete destination files.

Linux Comparison Commands

ls
pwd
cd
mkdir test-folder
rmdir test-folder
ip addr
ping 127.0.0.1
traceroute example.com
dig example.com
df -h
du -h
ps aux
top

Why this matters:

• Linux command practice helps you understand the same troubleshooting ideas across operating systems.
• Exact commands differ, but the goal is often the same: identify the system, check network state, inspect storage, and view running processes.

Mini Lab

Goal:

• Practice safe command-line troubleshooting.

Windows:

1. Run hostname.
2. Run whoami.
3. Run winver.
4. Run ipconfig.
5. Run ipconfig /all.
6. Run ping 127.0.0.1.
7. Run nslookup example.com.
8. Run netstat -ano.
9. Run sfc /scannow.
10. Run ipconfig /?.

Record:

• Computer name:
• Current user:
• IPv4 address:
• Default gateway:
• DNS server:
• Did loopback ping work?
• Did DNS lookup work?
• One listening port from netstat -ano:

Linux:

1. Run hostname.
2. Run whoami.
3. Run ip addr.
4. Run ping -c 4 127.0.0.1.
5. Run df -h.
6. Run ps aux.
7. Run top, then press q.

Record:

• Hostname:
• Current user:
• IP address:
• Root filesystem free space:
• One running process:

Quick Check Before Quiz

You are ready for the OS-4 quiz when you can answer these without looking:

• Which command shows full Windows IP configuration?
• Which command tests DNS name resolution?
• Which command shows active connections and process IDs?
• Which command repairs protected Windows system files?
• Which command forces Group Policy refresh?
• Which commands can erase data if misused?