API and Web Service Troubleshooting Questions

Knowledge of how web services and application programming interfaces operate and methods to debug common failures. Candidates should understand request and response flows, status codes and error semantics in Hypertext Transfer Protocol and its secure variant, representational state transfer principles, authentication and authorization failures, rate limiting and throttling, serialization and deserialization problems, and performance factors such as timeouts and retries. The topic includes practical use of tools to exercise endpoints, inspect headers and payloads, correlate API logs and traces, and isolate whether an issue is client side, network related, or server side.