Mobile Networking and API Integration Questions

Covers the design and implementation of network communication between mobile clients and backend services. Core protocol knowledge including Hypertext Transfer Protocol and secure Hypertext Transfer Protocol, representational state transfer principles, request and response serialization such as JavaScript Object Notation and protocol buffers, and API patterns suitable for mobile consumption. Platform specific implementation details including Apple iOS networking stacks and libraries such as URLSession, Android libraries such as OkHttp and Retrofit, and cross platform considerations. Reliability and resilience topics including network connectivity change handling, connection pooling, retry strategies and exponential backoff, timeout management, interceptors and middleware, circuit breaker and rate limiting patterns, and error classification and recovery. Performance and efficiency topics including request batching, compression, payload size reduction, caching strategies, cache invalidation, offline first approaches, local data storage and synchronization, conflict resolution strategies, and optimization for bandwidth constrained networks. Security and authentication including Transport Layer Security and certificate pinning, secure sockets layer considerations, token based authentication and refresh flows including Open Authorization and JSON Web Tokens, secure storage of credentials, and certificate and key management. Testing, debugging and observability including network mocking and stubbing, integration testing strategies, logging and telemetry for network flows, monitoring for latency and error rates, and handling of streaming and real time channels such as WebSocket and long polling when applicable.

EasyTechnical

28 practiced

Explain the differences between HTTP and HTTPS and why mobile applications should default to HTTPS for all network calls. In your explanation include threats TLS prevents (e.g., MITM, tampering), how HTTPS affects caching, certificate validation basics, and the operational implications for mobile (e.g., captive portals, enterprise proxies).

HardTechnical

23 practiced

Design how to share networking and retry logic between an iOS app using URLSession and an Android app using OkHttp. Identify which components (models, serialization, retry policy, backoff algorithms) can be shared via Kotlin Multiplatform or shared libraries, and which must remain platform-specific (background tasks, native push integration). Provide API boundaries and an example of the public interface.

EasyTechnical

27 practiced

In Swift, implement a simple networking function fetchUser(id: String) async throws -> User that performs a GET to /users/{id} using URLSession. Requirements: use Codable for response decoding, set a 30s timeout, handle HTTP status codes (200 success, others throw), and propagate network errors cleanly. Outline error types you would return.

HardTechnical

25 practiced

How would you ensure idempotency and deduplication for server-side operations that may be retried by mobile clients? Discuss idempotency keys, server-side token storage and garbage collection, idempotent HTTP methods, and trade-offs such as storage costs versus correctness.

EasyTechnical

28 practiced

Describe practical strategies a mobile app should use to handle changes in network connectivity (online, offline, flaky networks) on both iOS and Android. Include how you would surface state to the UI, queue or pause requests, retry policies, and when to fall back to local data.

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