IPv4 Addressing & Networking Fundamentals Link to heading

IPv4 Addressing Link to heading

An IPv4 address (e.g., 192.168.1.10) is composed of 32 bits divided into four octets (8 bits each).

  • Each octet ranges from 0–255 (256 possible values).
  • Structured with a network portion and a host portion.
  • Example: 192.168.1.10 → 192.168.1 = network, 10 = host.

Analogy:
Network = colony in a city
Host = individual houses within that colony

Key Facts:

  • IPv4 = 32 bits → 4 octets
  • 8 bits × 4 = 32 bits = 4 bytes
  • Each octet = 8 bits, range 0–255

Number Conversions Link to heading

Understanding number systems is essential for networking.

Conversion Types Link to heading

  • Binary ↔ Decimal
  • Binary ↔ Hexadecimal
  • Decimal ↔ Hexadecimal

Number System Bases Link to heading

  • Binary (Base 2): Digits 0, 1
  • Decimal (Base 10): Digits 0–9
  • Hexadecimal (Base 16): Digits 0–9, A–F
  • Octal (Base 8): Digits 0–7

Common Powers of 2:
2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, …

Subnetting Basics Link to heading

Subnetting = dividing a larger network into smaller sub-networks.

Benefits:

  • Enhanced security
  • Improved performance (less broadcast traffic)
  • Easier management & troubleshooting

CIDR Notation Link to heading

Compact subnet representation.
Example: 192.168.1.0/24 → 24 bits for network, 8 bits for hosts (256 addresses).

CIDR improves IP management by reducing address waste.

IP Address Classes Link to heading

Traditional classification based on leading bits:

  • Class A

    • Range: 1.0.0.0 – 126.255.255.255
    • Network bits: 8, Host bits: 24
    • Usage: Large enterprises, government
    • Note: 127.0.0.1 reserved for loopback

  • Class B

    • Range: 128.0.0.0 – 191.255.255.255
    • Network bits: 16, Host bits: 16
    • Usage: Universities, medium networks

  • Class C

    • Range: 192.0.0.0 – 223.255.255.255
    • Network bits: 24, Host bits: 8
    • Usage: Small businesses, home networks

  • Class D

    • Range: 224.0.0.0 – 239.255.255.255
    • Usage: Multicast (e.g., streaming)

  • Class E

    • Range: 240.0.0.0 – 255.255.255.255
    • Usage: Experimental/research

Types of IP Addresses Link to heading

  • Public IP: Globally routable, external communication
  • Private IP: Local networks (LAN), not routable externally
  • Static IP: Manually assigned, constant
  • Dynamic IP: Assigned via DHCP, changes over time

Example Communication:

  • Source: 192.168.1.10 (private/internal)
  • Destination: 45.77.146.37 (public/external)

IPv6 Link to heading

Developed to solve IPv4 exhaustion.

  • Uses 128-bit addressing → vastly larger pool of addresses.

MAC Address (Media Access Control) Link to heading

  • Hardware-level unique identifier for NICs.
  • Represented in hexadecimal (e.g., 00:1A:2B:3C:4D:5E).
  • Hard-coded into device hardware, permanent.

Real SOC Scenario Link to heading

A SOC analyst may detect multiple devices showing the same MAC address.

Possible Causes:

  • MAC spoofing (attacker forging MAC)
  • MITM attack (intercepting/altering communications)

Action:
Immediate investigation required to identify root cause and mitigate threats.