Networking fundamentals underpin every distributed system and web application. Senior engineers are expected to understand not just what TCP does, but how the three-way handshake works, why Nagle’s algorithm exists, and what actually happens when you type a URL into a browser.
These 13 questions cover the networking concepts most relevant to backend and full-stack interviews: protocol differences, connection lifecycle, DNS resolution, TLS handshakes, and HTTP/2 improvements. Understanding these deeply helps you debug production issues and make informed architectural decisions.
The TCP three-way handshake establishes a reliable, ordered connection between a client and server before any application data is exchanged.
Read full answer →TLS (Transport Layer Security) provides authentication, confidentiality, and integrity for network connections.
Read full answer →TCP and UDP are both transport layer protocols that sit on top of IP, but they make fundamentally different trade-offs between reliability and performance.
Read full answer →HTTP (Hypertext Transfer Protocol) is the application-layer protocol for transferring web resources — HTML, JSON, images, etc.
Read full answer →WebSockets are a protocol (RFC 6455) that provides full-duplex, persistent communication over a single TCP connection.
Read full answer →REST (Representational State Transfer) and gRPC are both approaches for building networked APIs, but they make fundamentally different tradeoffs optimized for different contexts.
Read full answer →The OSI (Open Systems Interconnection) model is a conceptual framework that divides network communication into 7 ordered layers, each providing services to the layer above and consuming services from the layer below.
Read full answer →CORS (Cross-Origin Resource Sharing) is a browser security mechanism that controls whether JavaScript running on one origin (scheme + host + port) can make HTTP requests to a different origin.
Read full answer →HTTP has evolved through three major versions, each addressing the performance limitations of its predecessor.
Read full answer →An HTTP/1.1 request is a plaintext message with four structural parts: **1.
Read full answer →HTTP status codes are three-digit integers grouped into five classes by their leading digit.
Read full answer →An HTTP method is **idempotent** if making the same request N times produces the same server state as making it once.
Read full answer →REST and GraphQL are both API paradigms, but they optimise for different constraints.
Read full answer →Focus on understanding concepts deeply enough to explain them in your own words. For each topic, practice articulating the trade-offs and real-world applications — interviewers care about practical judgment, not textbook definitions.
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