The Internet and the World Wide Web

AQA 4.7.3 — The Internet and the World Wide Web

Retrieval: Protocols and Standards named HTTP and TCP/IP without fully explaining what they're actually working together to deliver. This lesson puts the whole picture together — what happens, step by step, when a web page loads at all.

Key vocabulary

• Internet — the vast, global network of interconnected networks and infrastructure itself.
• World Wide Web (WWW) — one specific service that runs on top of the Internet: a system of linked documents (web pages) accessed via browsers.
• DNS (Domain Name System) — translates human-readable domain names (e.g. itskillforge.co.uk) into the numeric IP addresses computers actually use to find each other.
• Web server — a computer that stores web pages and sends them out in response to requests.

Understand — the Internet is infrastructure; the Web is one service on it

The Internet is the underlying global network of cables, routers and infrastructure — it existed, and was used for things like email, before the Web did. The World Wide Web is one specific service built on top of that infrastructure: linked pages, accessed by a browser using HTTP. Email, file transfer and video calling are all separate services that also run over the same underlying Internet — the Web is just the most visible one.

Visualise — what happens when a URL is typed in

1. Browser needs the IP address for "itskillforge.co.uk"
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2. DNS lookup: domain name ──▶ IP address (e.g. 192.0.2.10)
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3. Browser sends an HTTP request to that IP address
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4. The web server at that address processes the request
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5. The web server sends the web page's content back
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6. The browser receives it and renders it on screen

Apply to scenario — trace the process

A student types www.itskillforge.co.uk into their browser and presses enter. Using the steps above, trace exactly what has to happen, in order, before any content appears on their screen at all.

(1: the browser doesn't know the numeric IP address for that domain name yet, so it performs a DNS lookup. 2: DNS returns the correct IP address. 3: the browser sends an HTTP request to the web server at that IP address. 4: the web server locates the requested page. 5: the web server sends the page's content back. 6: the browser renders it on screen.)

Analyse — what breaks, and where

For each fault, analyse which specific stage of the process above has failed:

1. The browser shows "This site can't be reached — DNS address could not be found."
2. The browser shows "This site can't be reached — connection timed out," even though the domain name resolved to a valid-looking IP address.
3. The page loads, but shows a "500 Internal Server Error" message instead of the expected content.

(1: the DNS lookup stage — the domain name couldn't be translated into an IP address at all. 2: the HTTP request stage — the browser knows where to send the request, but the web server isn't responding. 3: the web server received and processed the request, but encountered an error while generating the response — the earlier stages all worked correctly.)

Evaluate — why DNS is distributed, not one central list

A single, central master list mapping every domain name in the world to its IP address would be a catastrophic single point of failure, and could never be updated fast enough for the whole world at once. Evaluate why a distributed, hierarchical system of many DNS servers, each responsible for part of the lookup and caching answers temporarily, is a more resilient design than one central list — what specifically would go wrong with a single central list that the distributed approach avoids?

Common mistake

Treating "the Internet" and "the Web" as identical terms. Using a messaging app, sending an email, or making a video call all use the Internet's underlying infrastructure without using the World Wide Web at all — the Web is one service among several, not a synonym for the whole Internet.

Looking ahead: the next lesson (Network Security) asks what can go wrong at any of the stages traced above if someone deliberately tries to intercept, redirect or disrupt this process — and how networks defend against exactly that.