Domain Name System

Lesson in the System Design Roadmap · Stage 8: Domain Name System

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What is Domain Name System?

A Domain Name System (DNS) translates a domain name such as www.example.com to an IP address.

DNS is hierarchical, with a few authoritative servers at the top level. Your router or ISP provides information about which DNS server(s) to contact when doing a lookup. Lower level DNS servers cache mappings, which could become stale due to DNS propagation delays. DNS results can also be cached by your browser or OS for a certain period of time, determined by the time to live (TTL).

  • NS record (name server) - Specifies the DNS servers for your domain/subdomain.
  • MX record (mail exchange) - Specifies the mail servers for accepting messages.
  • A record (address) - Points a name to an IP address.
  • CNAME (canonical) - Points a name to another name or CNAME (example.com to www.example.com) or to an A record.

Services such as CloudFlare and Route53 provide managed DNS services. Some DNS services can route traffic through various methods:

*   Prevent traffic from going to servers under maintenance
*   Balance between varying cluster sizes
*   A/B testing
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Free resources to learn Domain Name System

Domain Name System: common questions

Can I learn Domain Name System in Hindi?

This lesson is written in English. Once you sign in, open it in the interactive course and ask the AI tutor to explain Domain Name System in Hindi or Hinglish. The tutor answers from this lesson’s own text, so it stays on the syllabus, and it runs on your own Google, OpenAI or Anthropic key.

Is this Domain Name System tutorial for beginners?

It is lesson 20 of 147 in the free System Design roadmap, in stage 8, Domain Name System. If you are new to System Design, start from stage 1 and come back here in order; if you already know the earlier stages, this lesson stands on its own.

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