One of the most important networking concepts on the CompTIA A+ exam is understanding the difference between TCP and UDP.
Both are transport layer protocols, but they behave very differently.
TCP (Transmission Control Protocol) is reliable and connection-based.
Think of TCP like sending a certified letter — you get confirmation it arrived.
UDP (User Datagram Protocol) is fast and connectionless.
Think of UDP like shouting across a room — fast, but no confirmation.
| Feature | TCP | UDP |
|---|---|---|
| Connection | Connection-based | Connectionless |
| Reliability | Guaranteed delivery | No guarantee |
| Speed | Slower | Faster |
| Error Checking | Yes | Minimal |
Use TCP when accuracy matters (web browsing, file transfers).
Use UDP when speed matters (gaming, streaming, VoIP).
If the question mentions reliability or guaranteed delivery → Think TCP.
If the question mentions speed, streaming, or live communication → Think UDP.