[CS Technical Interview 3] Network That Opens Up Communication

How does the Internet work, and how do browsers fetch web pages? A core CS (computer-science) lecture, organizing network concepts along the OSI 7-layer model, to enable self-explanation of this question. Structured for intuitive understanding through diagrams and flow-centric explanations, and it organizes concepts frequently appearing in technical interviews—such as Transport Layer (TCP/UDP), IP Address, NAT, HTTPS—by linking them to actual questions.