Networking

Networking and OSI Model - Interview Preparations

This page is a compact interview prep sheet for networking fundamentals.

OSI Model

• Layer 1: Physical
• Layer 2: Data Link
• Layer 3: Network
• Layer 4: Transport
• Layer 5: Session
• Layer 6: Presentation
• Layer 7: Application

TCP vs UDP

• TCP is connection-oriented and reliable.
• UDP is connectionless and lower overhead.
• TCP is preferred for correctness and ordered delivery.
• UDP is preferred when latency matters more than retries.

Useful Topics

• IP addressing and subnetting.
• DNS lookup flow.
• Routing and default gateways.
• NAT and firewalls.
• TLS handshake basics.

Common Questions

• What happens when you type a URL in a browser?
• How does a TCP handshake work?
• What is the difference between a switch and a router?
• How do DNS and caching affect request latency?

Practical Notes

• Describe network flows step by step.
• Mention both protocol and purpose in answers.
• Tie theory back to real debugging: DNS, routing, ports, and TLS.