Ten billion pages in five days, politely, without losing progress: fetchers and parsers, domain locks, bandwidth math, deduplication and a crawl that stays fresh. One-hour boards for junior, senior and staff.
Data engineers building storage, streaming and processing systems.
Your approach: Use diagrams or prose for data contracts, state ownership, throughput, ordering and recovery where the brief requires them.
Design a Web Crawler. Ten billion pages in five days, politely, without losing progress: fetchers and parsers, domain locks, bandwidth math, deduplication and a crawl that stays fresh. One-hour boards for junior, senior and staff. Work from the scoping questions below. State assumptions for any unspecified load, guarantee or target, then trace your design end to end. Explain one difficult case and a credible alternative; the worked example is a reference, not a required implementation.
Resolve the scoping questions for a Web Crawler. Separate stated behavior from assumptions, and identify what is outside your design.
Declare relevant volume, latency, freshness, quality or cost targets with units. Show calculations or an evaluation plan that can test them; unspecified targets are your assumptions, not hidden pass criteria.
Explain how your guarantees hold in a difficult case relevant to this subject. Address: Priority? One pass or continuous?
Identify users, required behavior and exclusions. Answer: How much, how fast? What is the output?
Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: Politeness? What is skipped?
Estimate the dominant workload and resource demand with units and explicit assumptions. For a learned system, also state how quality is measured and what data is available.
Draw or describe the responsibilities needed for a Web Crawler. Trace a representative request, event or job from its input to a visible result; identify durable state owners.
Walk through a difficult case step by step, including detection and recovery. Consider: Duplicates? Do we choose the seeds? Priority? One pass or continuous?
Compare a credible alternative using your chosen workload and guarantees. Explain a remaining risk, a signal to watch and when you would change the design.