Networking Fundamentals

The protocols and infrastructure connecting systems: routing, switching, VPNs, and load balancing.

Concepts

The layered models networking is reasoned about in — physical up to application — and where common protocols and problems live.

How traffic gets forwarded within a local network (switching) versus across different networks (routing).

Encapsulating traffic inside another protocol to create a private, often encrypted path across an untrusted network.

Distributing traffic across multiple backend instances — algorithms, health checks, and layer 4 vs layer 7 balancing.

How devices get an IP address automatically, and how domain names get resolved into one.

Systematically isolating where in the stack a connectivity problem actually lives, instead of guessing.