How does the internet turn a web address you type into a connection to the right server?
The structure of the internet, the Domain Name System (DNS), URLs and IP and MAC addressing, the difference between the internet and the world wide web, and the protocols HTTP, HTTPS, FTP and the client-server model of the web.
An OCR H446 answer on the structure of the internet: the Domain Name System, URLs, IP and MAC addressing, the distinction between the internet and the world wide web, and the protocols HTTP, HTTPS and FTP within the client-server model of the web.
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What this dot point is asking
OCR wants the structure of the internet, how DNS resolves a domain name to an IP address, the parts of a URL, the difference between IP and MAC addresses, the distinction between the internet and the world wide web, and the web protocols (HTTP, HTTPS, FTP) within the client-server model. Expect a "describe the role of DNS" question and an "IP versus MAC" question.
The answer
The internet versus the world wide web
URLs, DNS and addressing
Web protocols and the client-server model
Examples in context
Typing a bank's address uses HTTPS so the login is encrypted; the padlock confirms the secure connection. DNS caching is why a site you have visited loads its address faster. Changing a website's hosting (a new IP address) is invisible to users because the domain name and DNS hide it. A switch uses MAC addresses to deliver a frame inside your home; a router uses IP addresses to send packets out to the server. OCR links this to the TCP/IP stack and to web development (the HTML the server returns).
Try this
Q1. State the difference between the internet and the world wide web. [2 marks]
- Cue. The internet is the global network of interconnected networks (infrastructure); the web is a service of linked pages and resources accessed over it.
Q2. State what DNS translates a domain name into. [1 mark]
- Cue. The numeric IP address of the server.
Q3. Explain why HTTPS rather than HTTP is used for online banking. [2 marks]
- Cue. HTTPS encrypts the data in transit, so login details and transactions cannot be read or altered by an interceptor, unlike plain HTTP.
Exam-style practice questions
Practice questions written in the style of OCR exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
OCR 20205 marksDescribe the role of the Domain Name System (DNS) when a user types a URL into a browser, and explain why DNS is needed.Show worked answer →
Role (up to 3): the DNS translates the human-readable domain name in the URL (for example www.example.com) into the numeric IP address of the server. The browser sends the domain to a DNS resolver, which queries the hierarchy of DNS name servers (root, top-level domain, then authoritative) until the matching IP address is returned; the browser then connects to that IP address.
Why needed (up to 2): people remember names far more easily than numeric IP addresses, and IP addresses can change while the domain name stays the same. DNS provides this name-to-address lookup so users need not know or track IP addresses. Markers reward "translates domain name to IP address" plus the human-memorability/decoupling reason.
OCR 20224 marksExplain the difference between an IP address and a MAC address, and state where each is used.Show worked answer →
IP address (2 marks): a logical address assigned to a device on a network, used at the internet layer to route packets between networks across the internet; it can change (for example when a device joins a new network or via DHCP).
MAC address (2 marks): a physical address built into the network interface card by the manufacturer, normally fixed, used at the link layer to identify a device on the local network so a switch can deliver a frame. Markers reward logical/routable versus physical/fixed and internet-layer versus link-layer use. A common error is treating the two as interchangeable.
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