🖥️ 1️⃣ Network Setup & Checks on Computers

Network setup and checks are extremely important for troubleshooting, labs, and exams such as CCST and basic networking. This section starts with Windows and then maps the same concepts to Linux and macOS.

🪟 A) Windows

🔹 How to Check Network Connection (GUI Method)

1. Open Settings
2. Go to Network & Internet

You can immediately see:

• Connected / Not connected
• Connection type (Wi-Fi or Ethernet)

Click Properties (Wi-Fi or Ethernet) to view:

• IPv4 address
• Subnet mask
• Default gateway
• DNS servers
• Network profile (Public / Private)

🔹 Command-Line Checks (VERY IMPORTANT)

Exams and real troubleshooting mostly use the command line.

Open Command Prompt:
Win + R → cmd → Enter

1️⃣ ipconfig

    ipconfig
      

What it shows:

• IPv4 address
• Subnet mask
• Default gateway

    IPv4 Address . . . : 192.168.1.10
    Subnet Mask  . . . : 255.255.255.0
    Default Gateway . : 192.168.1.1
      

🔴 Special Case: 169.254.x.x

    IPv4 Address : 169.254.12.45
      

Meaning:

• APIPA address
• DHCP server not reachable
• No Internet
• No default gateway

2️⃣ ping google.com

    ping google.com
      

What it checks:

• Internet connectivity
• DNS resolution
• Packet delivery

Successful result:

    Reply from xxx.xxx.xxx.xxx
      

If it fails:

• No Internet
• DNS issue
• Gateway unreachable

3️⃣ tracert google.com

    tracert google.com
      

What it shows:

• Path taken by packets
• Routers between PC and destination

    PC → Router → ISP → Internet → Google
      

🔧 Common Windows Network Problems (Exam Gold)

❌ Problem 1: No IP Address

    ipconfig → No IPv4 address
      

Possible causes:

• DHCP server down
• Ethernet cable unplugged
• Wi-Fi not connected

❌ Problem 2: 169.254.x.x

Meaning:

• DHCP request failed
• System self-assigned IP

Fix:

    ipconfig /release
    ipconfig /renew
      

❌ Problem 3: Ping Fails

    ping google.com → Request timed out
      

Possible reasons:

• Default gateway missing
• DNS issue
• Firewall blocking

Test gateway:

    ping 192.168.1.1
      

🧠 Windows Troubleshooting Flow (Exam Ready)

    Check cable / Wi-Fi
            ↓
    ipconfig
            ↓
    Valid IP?
      Yes → ping gateway
      No  → DHCP issue
            ↓
    ping google.com
            ↓
    Internet OK / Not OK
      

🐧 B) Linux (Quick Mapping)

🔹 Check IP Address

    ip a
      

    ifconfig
      

🔹 Check Internet

    ping google.com
      

🔹 Check Route

    traceroute google.com
      

🍎 C) macOS (Quick Mapping)

🔹 GUI Method

System Settings → Network → Wi-Fi / Ethernet

🔹 Terminal Commands

    ifconfig
    ping google.com
    traceroute google.com
      

🧠 FINAL EXAM TIPS (VERY IMPORTANT)

• ipconfig → IP & DHCP check
• ping → Connectivity test
• tracert → Path analysis

📱 2️⃣ Network Setup & Checks on Mobile Devices

Mobile devices are wireless-first endpoint devices. Unlike computers, they rely heavily on Wi-Fi and cellular networks, so checks are simpler but extremely important for troubleshooting and exams.

🤖 A) Android

🔹 Wi-Fi Setup (Step-by-Step)

Path: Settings → Wi-Fi

1. Turn Wi-Fi ON
2. Select the SSID (network name)
3. Enter the password
4. Tap Connect

After connection, check:

• Status → Connected
• Signal strength (📶)
• “Connected, internet available”

Tap the connected network to view:

• IP address
• Gateway
• DNS
• Link speed

🔹 Mobile Data Check (Cellular Internet)

Path: Settings → Network & Internet → Mobile Network

Verify:

• Mobile Data = ON
• Signal bars visible
• Network type: 4G / LTE / 5G

🔹 Android Troubleshooting (VERY IMPORTANT)

✔ 1️⃣ Toggle Airplane Mode

    Turn ON → wait 10 seconds → Turn OFF
      

Fixes:

• Network refresh
• Signal re-registration

✔ 2️⃣ Forget & Reconnect Wi-Fi

Settings → Wi-Fi → Tap Network → Forget
Reconnect by entering the password again.

Fixes:

• Wrong password issues
• Cached network errors

✔ 3️⃣ Reset Network Settings (Last Option)

Settings → System → Reset Options → Reset Wi-Fi, Mobile & Bluetooth

🔴 Common Android Network Issues (Exam Gold)

🍏 B) iOS (iPhone / iPad)

🔹 Wi-Fi Setup

Path: Settings → Wi-Fi

1. Turn Wi-Fi ON
2. Select the network
3. Enter the password

Tap the (i) icon to view:

• IP address
• Router
• DNS

🔹 Cellular (Mobile Data) Check

Path: Settings → Mobile Data → ON

Verify:

• Mobile Data enabled
• Signal bars visible
• 4G / 5G indicator near signal

🔹 Common iOS Fix (MOST IMPORTANT)

Reset Network Settings

    Settings → General
    → Transfer or Reset iPhone
    → Reset
    → Reset Network Settings
      

🧠 Mobile Networking Characteristics (Extra Knowledge)

🛠️ 3️⃣ Networking Utilities

Networking utilities are basic diagnostic tools used to identify where a network problem exists—device, gateway, DNS, route, or service.

🔹 1️⃣ ping — Reachability Test

What ping does:

• Checks if a destination is reachable
• Tests basic connectivity
• Measures latency (delay)

    ping 8.8.8.8
      

What it confirms:

• Network path exists
• Packets can travel and return
• Round-trip time in milliseconds

How it works:

• Sends ICMP Echo Request
• Receives ICMP Echo Reply

🔴 If ping fails

🔹 2️⃣ tracert / traceroute — Path Discovery

What it does:

• Shows each router (hop) packets pass through
• Helps find where the connection breaks

Commands:

    Windows:
    tracert google.com
      

    Linux / macOS:
    traceroute google.com
      

What it shows:

    PC → Router → ISP → Internet → Destination
      

• Each line represents one hop

When to use:

• Slow internet
• Ping works but site not loading
• To identify ISP or routing problems

🔹 3️⃣ nslookup — DNS Troubleshooting

What nslookup does:

• Converts domain name to IP address
• Verifies DNS server functionality

    nslookup google.com
      

Successful output shows:

• DNS server address
• Resolved IP address

🔴 If it fails

🔹 4️⃣ ipconfig / ifconfig — IP Configuration

What it shows:

• IP address
• Subnet mask
• Default gateway
• DNS servers

    Windows:
    ipconfig
      

    Linux / macOS:
    ifconfig
    or
    ip a
      

🔴 Special Case (Exam Favorite)

    169.254.x.x
      

Meaning:

• DHCP failed
• Self-assigned APIPA address

DHCP renew (Windows):

    ipconfig /release
    ipconfig /renew
      

🔹 5️⃣ netstat — Connections & Ports

What netstat does:

• Shows active network connections
• Displays listening ports
• Identifies protocols (TCP / UDP)

    netstat
      

Common useful option:

    netstat -an
      

Helps identify:

• Running services
• Open ports (security checks)
• Suspicious connections

🧠 How to Use Utilities Together (Real Troubleshooting Flow)

    ipconfig        → Check IP
         ↓
    ping gateway    → Local network
         ↓
    ping 8.8.8.8   → Internet reachability
         ↓
    nslookup site   → DNS check
         ↓
    tracert site    → Path issue
      

📶 4️⃣ Wireless Settings (SSID, Authentication, WPA)

Wireless settings decide who can connect, how securely, and how well a Wi-Fi network performs. This topic is very important for exams and real-world networks.

📡 A) SSID (Service Set Identifier)

🔹 What is SSID?

An SSID is simply the name of a Wi-Fi network. It is what you see when your phone or laptop scans for available Wi-Fi.

Examples:

• Home_WiFi
• Office_5G
• Campus_WLAN

🔹 Hidden SSID

What is a Hidden SSID?

• Wi-Fi name is not broadcast
• Network does not appear in Wi-Fi list
• User must manually enter SSID and password

Used in:

• Offices
• Labs
• Small security setups

🔐 B) Authentication

🔹 What is Authentication?

Authentication is the process of verifying who is allowed to connect to a Wi-Fi network.

🔹 Common Authentication Types (Exam Ready)

🔹 WPA-PSK (Personal)

WPA-PSK uses a shared password and is commonly used in homes and small offices.

🔹 Enterprise Authentication

Enterprise authentication uses a username and password (or certificates) along with a RADIUS server.

• Corporates
• Universities

🔒 C) WPA Modes (VERY IMPORTANT)

🔹 WPA (Old)

• Weak encryption
• Easily crackable
• Not recommended

🔹 WPA2 (Most Common)

• Uses AES encryption
• Secure and stable
• Still widely used

🔹 WPA3 (Best & Modern)

• Strongest encryption
• Protection against brute-force attacks
• Safer on public Wi-Fi

📊 WPA Comparison (Exam Ready)

⚡ Common Wireless Problems & Fixes