DNS - Domain Name System

less than 1 minute read

Translates human-readable domain names to machine-readable IP Addresses.

Browser asks DNS resolver for the IP address. It could be

  • ISP
  • Service like CloudFlare 1.1.1.
  • Google 8.8.8.8

If DNS resolver does not have the IP address in its cache, it asks the respective Authoritative nameservers

How does DNS resolver finds the authoritative name server?

3 levels of Authoritative name servers

  • Root nameservers
  • Top Level Domain (TLD) NameServer
  • Authoritative nameservers
User's Computer
      |
      v
+-------------------+
| DNS Resolver      |
| (1) Cache         |
+-------------------+
      |
      v
+-------------------+
| Root Name Server  |
| (2) Refers to .com|
+-------------------+
      |
      v
+-------------------+
| TLD Name Server   |
| (3) Refers to     |
|     example.com   |
+-------------------+
      |
      v
+-------------------+
| Authoritative     |
| Name Server       |
| (4) Provides IP   |
|     address       |
+-------------------+
      |
      v
User's Computer
(5) Receives IP Address
      |
      v
+-------------------+
| Establishes       |
| Connection to     |
| www.example.com   |
+-------------------+

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