Exploring the TCP/IP Model

TCP/IP was born out of a research project funded by ARPA in the 1960s. Its aim was to create a resilient, decentralized network, which led to the creation of ARPANET, the predecessor of the modern internet.

TCP/IP model consists of four layers: Application, Transport, Internet, and Network Interface. This layered approach allows for modular troubleshooting, development, and the abstraction of communications processes.

TCP ensures reliable and ordered data transmission, while UDP is faster, simpler but less reliable. Surprisingly, DNS queries typically use UDP, favoring speed over guaranteed delivery.

IPv4's 32-bit address space seemed huge in the 1980s but became insufficient due to rapid internet expansion. This led to the development of IPv6 with a massive 128-bit address space.

Sockets are the end-points in a network communication session. Uncommonly known, the term 'socket' was coined as an analogy to electrical sockets, symbolizing the endpoint for a connection.

Each TCP/IP connection has a unique combination of IP address and port number. Interestingly, port numbers below 1024 are reserved for well-known services, like HTTP (80) and FTP (21).

TCP/IP was designed to survive nuclear attacks, with no central authority, allowing communication even if parts of the network were destroyed. This robustness is a cornerstone of today's global internet reliability.