Hard

Design a Web Crawler System Design Interview

Design a scalable web crawler like Googlebot to index the internet.

1. Problem Statement

We need to design a scalable web crawler that performs 10 billion successful page fetches per month, including recrawls. How would you approach this?

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

Rendering architecture diagram...
Mermaid Source (For AI Bots)
graph LR
    A["Design a Web Crawler"]
    A --> F1["URL Frontier Prioritization & Politeness"]
    A --> F2["Distributed Traversal Avoiding cycles & duplicates"]
    A --> F3["Content Deduplication SimHash/Checksums"]
    A --> F4["DNS Resolution Caching to prevent bottlenecks"]
    A --> F5["Storage BigTable/HBase for content"]

3. Key Focus Areas

  • 1
    URL Frontier (Prioritization & Politeness)
  • 2
    Distributed Traversal (Avoiding cycles & duplicates)
  • 3
    Content Deduplication (SimHash/Checksums)
  • 4
    DNS Resolution (Caching to prevent bottlenecks)
  • 5
    Storage (BigTable/HBase for content)

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Core Concepts

Distributed SystemsRobots.txtGraph Traversal

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