API Integration and Networking Questions

Making and managing network requests to external services and third party APIs, including HTTP fundamentals and REST principles. Topics include constructing requests, headers and authentication schemes such as token handling and refresh flows, parsing and serializing JSON, handling HTTP status codes, network error handling, timeout and retry strategies, backoff, offline and caching strategies, security concerns such as HTTPS and certificate pinning, and familiarity with common networking libraries on different platforms. Candidates should demonstrate the ability to integrate external APIs reliably and securely and to reason about networking trade offs.

EasyTechnical

46 practiced

Describe the HTTP status code classes (2xx, 3xx, 4xx, 5xx). For each class provide concrete examples of how a mobile client should react: what UI to show, when to retry automatically, how to handle redirects, and how to handle authentication-related codes (401/403). Explain how to implement a generic response handler in a mobile networking layer that categorizes actions by status class.

MediumTechnical

33 practiced

Write Kotlin code (Android) that implements an exponential backoff retry mechanism with jitter for network requests. The function should accept initialDelayMs, maxDelayMs, maxAttempts, and a suspend lambda that executes the network call and returns a Boolean indicating success. Ensure the implementation is cancelable and does not block the main thread (use coroutines).

HardTechnical

46 practiced

Design secure flows for exchanging temporary credentials between a mobile app and your backend. Compare OAuth2 Authorization Code with PKCE, device code flow, mutual TLS (mTLS), and proof-of-possession tokens. State which approach you'd pick for a consumer mobile app needing offline refresh and justify your choice.

MediumTechnical

44 practiced

You are receiving reports of intermittent network failures affecting a subset of Android devices in the wild. Describe a step-by-step triage and debugging plan: how to reproduce the issue, what logs and telemetry to gather, how to use device farms or packet captures, how to isolate whether it is client, carrier, or server related, and mitigations you could ship quickly.

EasyTechnical

63 practiced

In Swift (5+), design Codable structs to represent a User with fields: id (Int), name (String), email (String or null), and metadata.last_login (ISO 8601 string). Show how you'd fetch and decode this User using URLSession, handle a missing/null email gracefully, and call a completion handler on the main thread with proper error handling.

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