Networking Basics · 3
📦 TCP vs UDP
Two ways to send data — pick the right one⏱ ~2 min
📮Certified mail vs. dropping leaflets
TCP is like certified/registered mail — you send it, the post office tracks it, and you get a confirmation when it's delivered. If it gets lost, it's resent. UDP is like dropping thousands of flyers from a helicopter — fast, covers everything, but you don't know exactly who got one. Different jobs need different approaches.
TCP
- •✅ Guaranteed delivery
- •✅ Packets arrive in order
- •✅ Error checking & retransmission
- •✅ Flow control
- •📧 Email, web browsing, file downloads, SSH
- •🐌 Slightly slower due to handshaking
UDP
- •⚡ No delivery guarantee
- •⚡ No ordering
- •⚡ No retransmission
- •⚡ No connection setup
- •🎮 Gaming, video calls, live streams, DNS
- •🚀 Much faster — fire and forget
The TCP 3-Way Handshake
- 1.SYN — Your computer says: 'Hey server, can we talk?'
- 2.SYN-ACK — Server replies: 'Sure! I'm ready.'
- 3.ACK — Your computer confirms: 'Great, let's go!'
Only after these 3 steps does real data start flowing. This is why TCP is slower to start but much more reliable.
★ FactWhen you're on a video call (Zoom, FaceTime), UDP is used intentionally. A tiny dropped frame looks like a brief glitch — but if TCP kept pausing to retransmit it, your whole call would freeze and stutter. A little imperfection is better than a lag spike.
🔒 SecuritySYN Flood Attack: Hackers exploit the TCP handshake by sending millions of SYN requests but never completing the ACK step. The server holds thousands of half-open connections in memory until it crashes. This is one of the most common DDoS techniques.
🧠Quick Checkfirst try = +5 XP
You're building a live streaming app. Which protocol should you use for the video feed?
🎮 Practice what you learned
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