Explain the purpose of DNS and how it works in simple terms.

Technical
Medium
Flipkart
106.8K views

This networking question checks your understanding of how human-readable addresses are resolved to IP addresses.

Why Interviewers Ask This

DNS is the backbone of internet connectivity; candidates must know how it translates domains to IPs. Interviewers assess your grasp of distributed systems and resolution hierarchies. Understanding DNS is vital for troubleshooting connectivity issues and designing scalable network architectures.

How to Answer This Question

Start with the analogy of a phonebook mapping names to numbers. Describe the recursive query process from the browser to the root server. Mention caching at different levels to improve speed. Briefly touch upon A records and CNAMEs.

Key Points to Cover

  • Domain to IP translation
  • Hierarchical server structure
  • Caching benefits
  • Resolution process

Sample Answer

DNS acts like the internet's phonebook, translating human-friendly domain names like flipkart.com into machine-readable IP addresses. When you type a URL, your browser queries a local resolver, which contacts root servers, then TLD servers, and finally authoritative servers to find the IP. This hierarchical lookup uses caching at every step to reduce latency. Understanding this flow helps in diagnosing why a site might be unreachable or slow to load.

Common Mistakes to Avoid

  • Skipping the hierarchy explanation
  • Confusing DNS with HTTP
  • Not mentioning caching

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