The internet, the web and digital currency — GCSE Computer Science practice questions

Question 1

Priya video-calls her cousin in Nairobi and then reads a recipe on a cooking website. Her friend says: "Both of those use the internet, but only the recipe uses the world wide web."

Which statement best describes the difference between the internet and the world wide web?

Accepted Answer

C: The internet is the global network of connected computers and networks; the world wide web is the collection of web pages and websites accessed using the internet.. The internet is the infrastructure that links devices all over the world. The web is just one service carried by it: the pages and sites Priya opens in a browser. Her video call travels over the internet too, but it is not a web page, so it is not part of the web.

Question 2

Amira types the URL of a museum's website into her browser. What does the DNS (domain name server) do?

Accepted Answer

C: It finds the IP address that matches the domain name and sends it back to the browser.. A DNS server holds a database of domain names and their matching IP addresses. It looks up the IP address for the domain name in the URL and returns it to the browser, which then sends its request to the web server at that IP address. The web server, not the DNS, stores and sends the page.

Question 3

A crowdfunding website records every pledge made in an invented digital currency, Kelpcoin, in a blockchain. Someone changes the amount of a pledge that was recorded three weeks ago on their own copy of the blockchain.

Why does this change not succeed?

Accepted Answer

D: Each block is linked to the next one and copies of the chain are held on many computers, so the changed copy no longer matches and is rejected.. A blockchain is a decentralised ledger: copies are held on many computers, and each time-stamped block is linked to the previous block. Changing an old block breaks its link with the blocks that follow it, and the altered copy no longer matches the copies held by everyone else, so it is rejected. Blocks can only be added, never altered, by anyone.