TCP/IP · DNS · HTTP/HTTPS · URL · World Wide Web · Cloud
CSZoneCambridge IGCSE Computer Science 0478
Internet vs World Wide Web
Two Different Things
The Internet: the global physical network of interconnected computers and servers. The infrastructure — wires, routers, protocols.
The World Wide Web (WWW): a collection of websites and web pages stored on servers and accessed via the internet using HTTP. A service that runs on the internet.
Other internet services: email (SMTP/POP3/IMAP), FTP, streaming, VoIP (Skype, Zoom) — not part of the WWW
TCP/IP & Protocols
The Rules of the Internet
TCP/IP: the fundamental protocol suite. TCP (Transmission Control Protocol) breaks data into packets and reassembles them; IP (Internet Protocol) addresses and routes each packet across networks.
HTTP/HTTPS: HyperText Transfer Protocol (Secure). Used by browsers to request and receive web pages. HTTPS adds SSL/TLS encryption.
FTP: file transfer; SMTP/POP3/IMAP: email; VoIP: voice over internet
DNS & URLs
Finding Websites by Name
DNS (Domain Name System): translates human-readable domain names (e.g. www.google.com) into IP addresses (e.g. 142.250.179.14) so computers can find each other.
Without DNS, you'd need to memorise IP addresses for every website
Exam Practice
Have a go at this question
Cambridge IGCSE 0478 style
Describe the role of DNS when a user types a web address into a browser.
3 marks
The browser sends the domain name to a DNS server [1]. The DNS server looks up the domain name in its database [1] and returns the corresponding IP address to the browser [1], which then uses the IP address to connect to the web server.
Key Takeaways
What to Remember
Internet: global network infrastructure; WWW: collection of websites using HTTP — different things
TCP: breaks data into packets and ensures delivery; IP: routes packets using addresses
DNS: translates domain names → IP addresses; URL: full web address including protocol