DNS: the internet's phone book
- You type www.bbc.co.uk.
- Your browser asks a DNS server for its IP address.
- If it doesn't know, it asks other DNS servers.
- The IP address comes back.
- Your browser contacts that address directly.
Internet vs web: DNS and browsers
TheoryPresent ▶
What this lesson covers
Topic 15 Networks and the internet
KS3 Computing · A network is computers joined up to share. The internet is a network of networks. Data crosses it in small numbered packets, following agreed rules called protocols.
Topic 16 The web
KS3 Computing · A web page is text written in HTML (what's on the page), styled with CSS (how it looks), sometimes with JavaScript (what it does). Your browser fetches it from a web server using a URL and HTTP.
Networks and Digital CommunicationCambridge Lower Secondary Computing 0860
You will learn to
- Explain why the internet and the web are not the same thing.
- Describe what DNS does, step by step, when you type a web address.
- Identify the protocol, domain and path in a URL.
Success criteria
- I can name one internet service that is not the web, like email.
- I can put the steps of a web request in the right order.
- I can take a URL apart and name each part.
Key words
Say each word, then read what it means. Every one is in the glossary too.
- DNS
- Domain Name System: turns website names into IP addresses.
- URL
- The full web address of something online.
- LAN / WAN
- Local Area Network: a network over a small area.
- Router
- Connects different networks and forwards packets.
- IP address
- A device's address on a network. IPv4 = 4 bytes.
- MAC address
- Fixed unique ID of a network card. 48 bits in hex.
- Packet
- A small numbered chunk of data sent across a network.
- Protocol
- A set of agreed rules for communication.
- Bandwidth / latency
- How much data a connection can carry per second.
- HTML
- Markup language for the content of web pages.
- CSS
- Language that styles how web pages look.
The explanation
Read it here, or open the study page below to go one step at a time with things to try.
Internet vs the web
- Internet = the physical network: cables, routers, satellites.
- World Wide Web = one service on it: linked pages in a browser. Email and games use the internet but aren't the web.
Reading a URL
A URL is the full address of one thing on the web: https://www.bbc.co.uk/news/technology?page=2
| Part | Example | Meaning |
|---|---|---|
| Protocol | https:// | Which rules. The s means encrypted |
| Domain | www.bbc.co.uk | Which server. DNS turns it into an IP address |
| Top-level domain | .co.uk | Country or type (.uk, .es, .com) |
| Path | /news/technology | Which page on the server |
| Query | ?page=2 | Extra information for the page |
Study it
Open the study page and go one step at a time.
Topic 15 · Year 7
Networks and the internet
A network is computers connected to share data. The internet is a network of networks. Data travels in small packets, following rules called protocols.
Topic 16 · Year 8The web
A web page is text written in HTML (what's on the page), styled with CSS (how it looks), sometimes with JavaScript (what it does). Your browser fetches it using a URL.
The steps for this lesson
- Topic 16, step 2: URLs (Take a URL apart)
Try it
Pages to explore
Check yourself
One question at a time. The reason shows after each answer.
Saved on this device.