The OSI model: understanding its seven layers

The seven OSI layers

1. Physical — transmitting bits over a physical medium.

2. Data Link — frames, MAC addresses and switching.

3. Network — IP addressing and routing.

4. Transport — TCP/UDP and ports.

5. Session — managing sessions.

6. Presentation — data representation and encryption-related functions.

7. Application — network services used by applications.

Remember

A typical switch operates at Layer 2 and a router at Layer 3. Multilayer devices can perform functions across layers.

Practice

Explain how DNS, TCP or QUIC, TLS and IP relate when a browser opens an HTTPS website.