# Lab OS-4: Command-Line Troubleshooting

Domain:
- 1.0 Operating Systems

Works on:
- Windows
- Linux

Does not require:
- macOS

## Goal

Build comfort entering commands and interpreting basic troubleshooting output.

## Windows Steps

Run:

```powershell
hostname
whoami
winver
ipconfig
ipconfig /all
ping 127.0.0.1
nslookup example.com
netstat -ano
sfc /scannow
ipconfig /?
```

Record:
- Computer name:
- Current user:
- Windows version/build:
- IPv4 address:
- Default gateway:
- DNS server:
- Loopback ping successful:
- DNS lookup successful:
- One active/listening port:
- SFC result:

## Linux Steps

Run:

```bash
hostname
whoami
ip addr
ping -c 4 127.0.0.1
df -h
ps aux
top
```

Press `q` to exit `top`.

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

## Safety Notes

Do not run destructive disk commands in this lab.

Know these for the exam, but do not experiment casually:
- `format`
- `diskpart`
- `robocopy` with mirror/delete options
- `chkdsk /f` or `chkdsk /r` on important disks without planning

## What You Should Learn

- `ipconfig /all` gives detailed IP configuration.
- `ping` tests reachability.
- `nslookup` tests DNS.
- `netstat -ano` shows connections, ports, and process IDs.
- `sfc /scannow` repairs protected Windows system files.
- `/?` shows command help.