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🔗 How Does the Internet Find Websites? — DNS Explained

Type a domain name and watch the DNS resolution process — from browser cache to root server to IP address.

Designed with the WJEC specification in mind
CS GCSE §1.3.1DigiTech GCSE §1.2.1

🤔 What is DNS?

DNS (Domain Name System) is like the internet's phone book. When you type "www.google.com", your computer needs to find the actual address (IP address) where Google lives on the internet.

🍕 Analogy: It's like asking for directions to "Tesco" — first you need to know which specific Tesco (the address), not just the name!
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Enter a domain name

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DNS Record Types

A
Maps domain → IPv4 address
AAAA
Maps domain → IPv6 address
CNAME
Alias to another domain name
MX
Mail server for the domain
NS
Nameserver for the domain
TXT
Text data (SPF, verification)
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Key Concepts

DNS (Domain Name System) translates human-readable domain names into IP addresses that computers use to communicate.

Recursive vs Iterative: Your ISP's resolver does the hard work (recursive) — it asks root, TLD, and authoritative servers in turn (iterative queries) and caches the results.

TTL (Time To Live) — how long a DNS record can be cached before it must be looked up again.

DNS Hierarchy: Root servers (.) → TLD servers (.com, .uk) → Authoritative servers (google.com)

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Exam Tips

  • GCSE: Know that DNS translates domain names to IP addresses and be able to explain why this is necessary
  • A-Level: Understand the DNS hierarchy: root → TLD → authoritative servers
  • Key point: DNS caching speeds up subsequent requests for the same domain
  • Remember: A records map to IPv4, AAAA to IPv6, CNAME creates aliases