AI & Technical question

Design a file download API. A client will send the URL of the file they want to download.

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What this question tests

Tests technical system design fundamentals: API contract, handling large files, and reliability under failure.

Clarify requirements: file size range, whether resumable downloads matter, expected concurrency.
Define the API contract: an endpoint accepting a file URL, returning a job ID or a redirect and stream.
Decide sync versus async: for large files, return a job ID immediately, let the client poll or use a webhook.
Address reliability: support range requests so downloads resume after a dropped connection, validate via checksum.
Address security: validate the source URL against an allowlist or scan before serving it back.
Define quality measurement: download success rate, average latency, resumption success rate.

Chooses an async, job-based design for large files instead of a blocking synchronous call.
Explicitly adds resumability via range requests, since that's the whole point of large-file downloads.
Adds a security check on the source URL, showing awareness of SSRF-style risk.

Designing only the happy path with no handling for interrupted or large downloads.
Ignoring security validation of an arbitrary client-supplied URL.

Chapters of the AI PM course that teach what this question tests.