How a web page reaches you
Typing an address starts a chain of requests. Understanding that chain makes both faults and online safety much easier to reason about.
Part of your national curriculum
- Computer systems and networks: Understand the hardware and software components that make up computer systems, and how they communicate with one another and with other systems
- Computer systems and networks: Understand how computer networks, including the internet, can provide multiple services such as the World Wide Web
- Creativity and digital literacy: Understand a range of ways to use technology safely, respectfully, responsibly and securely, including protecting online identity and privacy
- Creativity and digital literacy: Recognise inappropriate content, contact and conduct, and know how to report concerns
Lesson overview
What you'll learn in this lesson
Describe how data travels across the internet
Key learning points
- • Names to numbers
- • Packets and responses
This lesson at a glance
- 20 minutes
- 10 parts to scroll through
- 3 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 10
Watch first
How a web page reaches you
An English teaching video on this topic from CPD College. Watch it, then scroll down for the lesson.
In a nutshell
Describe how data travels across the internet
Explore the idea
Part 2 of 10
Learn
Names to numbers
A domain name is looked up by DNS and turned into an IP address — the internet's equivalent of a postcode for the server.
Explore the idea
Part 3 of 10
Learn
Packets and responses
Your request is split into packets, routed separately, and reassembled. The server replies with HTML, CSS and images that the browser renders.
Quick check
Part 4 of 10
Quick check
DNS turns a domain name into…
Quick check
Part 5 of 10
Quick check
Data crosses the internet in…
Quick check
Part 6 of 10
Quick check
The browser's job is to…
Challenge round
Part 7 of 10
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Challenge round
Part 8 of 10
Game · Fill the gaps
Finish the sentences
Choose the word that belongs in each gap.
A domain name is looked up by DNS and turned into an IP address — the ____'s equivalent of a postcode for the server.
Your request is split into ____, routed separately, and reassembled.
Mastery quiz
Part 9 of 10
Marked quiz
End of lesson quiz: How a web page reaches you
3 questions, marked with the reasoning shown. No timer.
1. DNS turns a domain name into…
2. Data crosses the internet in…
3. The browser's job is to…
Lesson round-up
Part 10 of 10
Lesson round-up
Ready when you are
Quiz score
Not sat
Games
Not played
Points this lesson
0
Best run
0 in a row
Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?
Ask LunaDo the work
Your written work for this lesson
This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.
How a supermarket checkout knows the price
When a barcode is scanned, the checkout does not store the price itself. It sends the barcode number to a database and reads back a record: product name, price, whether it needs an age check. The record is the single place the price lives, so changing one row changes every till in the shop at once.
Problems come from bad data, not bad scanners. If two products share a barcode, or a price update reaches the shop overnight but the till holds an old copy in its cache, customers are charged the wrong amount. Shops check this with test transactions: scan a known item, expect a known price, record what actually happened.
Good systems also log every scan. If a customer complains, the log shows exactly which record was used and when.
Written for Good Learning Co.
Reading questions
- Write in your own words what the checkout sends and what it receives back.
- Explain one way bad data could cause a wrong price, and how logging helps find it.
- Design a test table with four tests for a new checkout, with expected and actual results.
Reading and notes
ReadingRead the lesson text again and note the key terms and how each one is used, in your own words — as you would for revision.
Half a page of notes
Extended writing
WritingExplain a real system that uses this idea — how it works, where it can go wrong, and how you would make it safer or better.
250–350 words
Algorithm on paper
DiagramWrite your steps out as pseudocode or a flowchart before you type anything, then photograph it.
1 flowchart or 10 lines
Code write-up
WritingCopy your code in, then explain underneath what each part does and what you had to fix.
Code + 5 sentences
Test table
Working outMake a test table: what you tried, what you expected, what actually happened.
4–6 tests
Saved as you type.
Part 1 of 10 · Watch & discover
How this is going
- Not looked at yet
Understand the hardware and software components that make up computer systems, and how they communicate with one another and with other systems
- Not looked at yet
Understand how computer networks, including the internet, can provide multiple services such as the World Wide Web
- Not looked at yet
Understand a range of ways to use technology safely, respectfully, responsibly and securely, including protecting online identity and privacy
- Not looked at yet
Recognise inappropriate content, contact and conduct, and know how to report concerns