What is DNS

Imagine if you had to remember the IP addresses of all the well-known websites that you visit frequently over the Internet. This means that you had to remember 104.18.3.119 to visit www.educative.io. Of course, this would not be possible/feasible because we often visit many websites in a day, and also IPs of websites can change over time.

The Domain Name System (DNS) solves this problem precisely. It is the Internet’s naming service that maps human-friendly names (like www.educative.io) to machine-readable names (like 104.18.3.119). DNS is implemented in the form of a distributed database for the following reasons:

  • Avoid becoming a Single Point Of Failure (SPOF).
  • Achieve low query latency so users can get responses from nearby servers.
  • Get a higher degree of flexibility during maintenance and updates/upgrades (for example using a different DNS name server if one is down, or DNS replying IPs to a different machine).

The slides below show the high-level flow of getting an IP for a website using DNS.

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