HTTP protocol

HTTP protocol interviews cover versions, methods, status codes, headers, cookies, caching, compression, and connection reuse—how clients and servers actually negotiate behavior.

Subtopics: HTTP versions, methods and status codes, headers and cookies, caching and compression, and keep-alive with connection reuse.

On interviews: compare HTTP/1.1 head-of-line blocking with HTTP/2 multiplexing, pick status codes for validation vs auth failures, and explain Cache-Control trade-offs.

Common pitfalls: wrong idempotency assumptions on methods, cookies without Secure/SameSite, and caching personalized responses without Vary.

Checklist:

• Map methods to safety and idempotency.
• Use headers deliberately for auth, caching, and security.
• Design cache keys and invalidation with validators.
• Reuse connections; align timeouts with upstream pools.