Question 1

What are HTTP status codes?

Accepted Answer

HTTP status codes are 3-digit numbers returned by servers to indicate request outcome. Categories: 1xx informational, 2xx success, 3xx redirect, 4xx client error, 5xx server error. Common codes: 200 OK, 404 Not Found, 500 Internal Server Error. Codes tell browsers and clients how to handle responses.

Question 2

What is the difference between 401 and 403?

Accepted Answer

401 Unauthorized: authentication required or failed - user needs to log in or provide valid credentials. 403 Forbidden: authenticated but not authorized - user lacks permission to access resource even with valid credentials. 401 = 'Who are you?', 403 = 'I know who you are, but you can't access this.'

Question 3

What causes 500 Internal Server Error?

Accepted Answer

500 is generic server error. Common causes: code exceptions, database connection failures, timeout errors, configuration issues, memory limits exceeded, syntax errors in server code. Debugging: check server logs for stack traces, verify database connections, test code locally, review recent changes, check error handling.

Question 4

What does 429 Too Many Requests mean?

Accepted Answer

429 indicates rate limiting: client sent too many requests in given time period. API responses include Retry-After header. Causes: aggressive polling, loop without delay, missing caching, distributed systems hitting same endpoint. Solutions: implement backoff, add delays, use caching, respect rate limits.

Question 5

How do I fix 404 Not Found errors?

Accepted Answer

404 troubleshooting: verify URL spelling, check resource exists, confirm routing configuration, verify file permissions, check case sensitivity, ensure server is running, verify API endpoint path matches documentation. For APIs: check endpoint definition, verify resource ID exists. For websites: check link validity, verify page published.

HTTP Status Code Reference

HTTP Status Codes (21 shown)

Status Code Categories

Common Troubleshooting

Developer Use Cases