[Day 1] 1. Overview and Revision

Purpose of the Lab

• Goal: Improve troubleshooting skills. No spoon-feeding will be entertained.
• Important Guidelines:
  1. Use private browsing to avoid cache storage issues.
  2. Uninstall any antivirus temporarily if required (be cautious while testing).
  3. Enable file extensions in Windows to easily identify file types.

Key Resource

• Search: "How to Ask Smart Questions" by Eric Steven Raymond (catb.org).
  • This resource teaches effective ways to ask questions and troubleshoot like a professional.

Learning Tip

• Visualization: Always relate technical concepts to real-life scenarios for better understanding.

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IP Address Classes

Classes of IP Addresses:

| Class | Range | Subnet Mask | Purpose | | ----- | --------------------------- | ------------- | ---------------------------- | | A | 1.0.0.0 - 126.255.255.255 | 255.0.0.0 | Large networks (e.g., ISPs) | | B | 128.0.0.0 - 191.255.255.255 | 255.255.0.0 | Medium-sized networks | | C | 192.0.0.0 - 223.255.255.0 | 255.255.255.0 | Small networks (e.g., homes) | | D | 224.0.0.0 - 239.255.255.255 | N/A | Multicasting | | E | 240.0.0.0 - 255.255.255.255 | N/A | Experimental/Reserved |

Types of IP Addresses:

• Public IPs: Accessible from the internet.
• Private IPs: Used within local networks. Common ranges:
  • Class A: 10.0.0.0 - 10.255.255.255
  • Class B: 172.16.0.0 - 172.31.255.255
  • Class C: 192.168.0.0 - 192.168.255.255

Special IPs:

• Loopback:
  • Range: 127.0.0.0 - 127.255.255.255
  • Used for testing and diagnostics (e.g.,
    Copy

    ping 127.0.0.1

    ).
• APIPA:
  • Range: 169.254.0.0 - 169.254.255.255
  • Assigned when a device cannot get an IP via DHCP.
• Reserved:
  • Class A addresses starting with
    Copy

    0

    (e.g.,
    Copy

    0.0.0.0

    ) are reserved.

IP Assignment Methods:

• Static: Manually assigned by an administrator.
• Dynamic: Automatically assigned by a DHCP server.

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What Happens When You Browse the Internet?

1. Visibility on the Internet:
   • Your actions online are visible to everyone, including potential attackers.
   • Bots vs. Humans:
     • A significant portion of internet traffic is generated by bots, not humans.
2. Bot Statistics (2017):
   • 48.2% of traffic: Human activity.
   • 51.8% of traffic: Bots.
   • This highlights that the internet is dominated by automated programs.
3. Protection Perspective:
   • Protecting yourself online often means guarding against bots, not just human attackers.

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The Internet: A Double-Edged Sword

• World Wide Web (WWW): Often likened to the "Wild Wild West" due to its vast, unregulated nature.
• Always be cautious and take steps to ensure your security.

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