The evasion angle is what separates this from a vanilla crawler design.
Start by clarifying requirements and constraints, then outline a high-level architecture covering URL frontier, fetcher, parser, and storage. Discuss detection avoidance techniques like rate limiting, user-agent rotation, and proxy management, while emphasizing ethical and legal considerations. Conclude with trade-offs and scalability.
Pro tip: Emphasize that avoiding detection is not just technical but also ethical; show awareness of robots.txt, terms of service, and potential legal issues. Propose a design that balances efficiency with respect for the target site.
Ask about scale, target site characteristics, politeness policies, and legal boundaries. Determine if the crawler is for a one-time job or continuous operation.
Outline components: URL frontier (priority queue), fetcher (HTTP client), parser (HTML/XML), deduplication, and storage. Mention distributed crawling if scale is large.
Discuss rate limiting, user-agent rotation, proxy pools, headless browsers, and CAPTCHA handling. Explain how to mimic human behavior and avoid patterns.
Analyze trade-offs between speed and stealth, cost of proxies, and complexity. Discuss how to scale horizontally while maintaining anonymity.
Highlight the importance of respecting robots.txt, terms of service, and copyright. Suggest implementing a politeness policy and obtaining permission when needed.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.