Networking Fundamentals

Internet Protocol (IP)

The Internet Protocol is the cornerstone of the TCP/IP architecture. It is a connectionless, best-effort protocol used to deliver packets between hosts on different networks.

Main tasks

Addressing — assigning unique addresses to hosts
Fragmentation — splitting packets when necessary to traverse smaller MTUs

IP versions

IPv4 — 32-bit addresses (e.g., 192.168.1.1)
IPv6 — 128-bit addresses (e.g., 2001:db8::1)

Private vs Public Addresses

Public — globally routable, assigned by ISPs
Private (RFC 1918) — not routable on Internet:
- 10.0.0.0/8
- 172.16.0.0/12
- 192.168.0.0/16

IP Address Classes

IP addresses from 0.0.0.0 to 255.255.255.255 are classified into 5 classes based on the first octet value:

Class	Range	Private IP Address
Class A	0 - 127	10.0.0.0 - 10.255.255.255
Class B	128 - 191	172.16.0.0 - 172.31.255.255
Class C	192 - 223	192.168.0.0 - 192.168.255.255
Class D	224 - 239	Multicast Addresses
Class E	240 - 255	Experimental Addresses