10 min read Intermediate Lesson 4 of 8
Part 2 — Under the Hood

TCP vs UDP Transport Layer

At the transport layer, data delivery boils down to a fundamental choice: **Guaranteed reliability** (TCP) or **maximum speed & low latency** (UDP).

TCP vs UDP Architectural Comparison

1. TCP (Transmission Control Protocol)

Connection-oriented (3-way handshake), ordered delivery, ACKs, retransmits lost packets, congestion control (HTTP, SSH, Email).

2. UDP (User Datagram Protocol)

Connectionless fire-and-forget datagrams, zero handshake overhead, tolerates dropped packets (Live Video, Gaming, DNS, HTTP/3 QUIC).

Quick Summary

  • TCP guarantees ordered packet delivery, while UDP prioritizes speed and real-time streams.
  • Next, we explore Web Servers & Reverse Proxies.