IP Addressing

Addressing & Subnetting

IPv4 & CIDR (Classless Inter-Domain Routing)

• Structure: 32-bit address. IPv4 vs IPv6 (Google).
• CIDR Notation: IP/PrefixLength (e.g., 192.0.2.0/24). What is CIDR? (DigitalOcean).
  • Prefix: Identifies the network.
  • Suffix: Identifies the host.
• Subnetting: Breaking a large block into smaller networks for efficiency and security.
  • /32: Single IP (Host).
  • /24: 256 IPs (Standard LAN).
  • /0: The entire internet (0.0.0.0/0 = Default Route).

Private Address Space (RFC 1918)

Non-routable on the public internet. Used within LANs/VPCs.

• 10.0.0.0/8
• 172.16.0.0/12
• 192.168.0.0/16

NAT (Network Address Translation)

Required to bridge Private and Public space due to IPv4 exhaustion. What is NAT? (Cisco).

• SNAT (Source NAT): Internal hosts accessing the internet. Router replaces Source IP with Public IP.
• DNAT (Destination NAT): External traffic accessing internal service (Port Forwarding).
• CGNAT (Carrier-Grade NAT): ISPs sharing public IPs among many customers.

IPv6

• Structure: 128-bit address (Hexadecimal).
• No NAT: Designed for end-to-end connectivity. Every device gets a global unicast address.
• Dual Stack: Running IPv4 and IPv6 simultaneously during transition.