Networking Fundamentals · lesson 2 of 17 · 12 min
TCP/IP model The TCP/IP model is the practical model that the internet actually uses. It has four layers that map roughly to the OSI model: Application: HTTP, DNS, SMTP, SSH — maps to OSI layers 5–7. Transport: TCP and UDP — maps to OSI layer 4. Internet: IP, ICMP — maps to OSI layer 3. Network Access (Link): Ethernet, Wi-Fi — maps to OSI layers 1–2. TCP vs. UDP TCP (Transmission Control Protocol): connection-oriented, reliable, ordered delivery. Uses a three-way handshake (SYN → SYN-ACK → ACK). Used for HTTP, SSH, email — anything where data must arrive correctly. UDP (User Datagram Protocol): connectionless, no delivery guarantee, no ordering. Faster and lower overhead. Used for DNS, video streaming, VoIP, online games — where speed matters more than perfection.
TCP vs. UDP
Try it: Which layer?
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