What is the OSI model?
Why Interviewers Ask This
This is a classic screening question for Networking roles. Hiring managers ask it early in interviews to gauge your baseline understanding and determine if you can communicate technical concepts clearly.
Answer
The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a communication system into 7 layers, allowing different systems and vendors to communicate. From top to bottom: Layer 7 — Application (HTTP, FTP, SMTP, DNS — user-facing services), Layer 6 — Presentation (data format translation, encryption, compression), Layer 5 — Session (managing sessions/connections between applications), Layer 4 — Transport (TCP/UDP, end-to-end communication, port numbers), Layer 3 — Network (IP addressing, routing), Layer 2 — Data Link (MAC addresses, framing, switches), Layer 1 — Physical (cables, signals, bits). Mnemonic: "All People Seem To Need Data Processing" (top to bottom).
Pro Tip
Before answering, structure your response: one-line definition → real-world analogy → concrete example from a project. This makes even complex Networking answers easy to follow.