IGCSE Computer Science C5

Understand the difference between the internet and the world wide web

Internet: The infrastructure — a global network of interconnected devices
WWW: A collection of websites and web pages accessed using the internet

Understand what is meant by a uniform resource locator (URL)

A text-based address for a web page and includes:
​​- The protocol (e.g. https://)

• The domain name (e.g. example.com)
• The file or web page path (e.g. /folder/page.html)

Describe the purpose and operation of hypertext transfer protocol (HTTP) and hypertext transfer protocol secure (HTTPS)

HTTP:

• Used to transfer web pages over the internet,

• not encrypted
  HTTPS:

• Same as HTTP, but includes encryption for secure communication

• , Encrypted using SSL/TLS

Explain the purpose and functions of a web browser

Main purpose:

• To render hypertext markup language (HTML)

• Display web pages
  Functions:

• Storing bookmarks and favourites,

• Recording user history,

• Allowing use of multiple tabs,

• Storing cookies, Providing navigation tools,

• Providing an address bar

Describe how web pages are located, retrieved and displayed on a device when a user enters a URL

1) Web browser: Sends the request for the web page
2) IP addresses: Used to identify the destination server
3) DNS (Domain Name Server): Converts the domain name to an IP address
4) Web server: Receives the request and sends back the requested web page
5) HTML: The page content is written in HTML, which is rendered by the browser

Explain what is meant by cookies and how they are used, including session cookies and persistent cookies

Session Cookie: Temporary; deleted when the browser is closed
Persistent Cookie: Stored for longer periods; remains after browser is closed

Explain the purposes of cookies

• Saving personal details (e.g. names, preferences)

• Tracking user preferences,

• Holding items in an online shopping cart,

• Storing login details for automatic sign-in

Understand the concept of a digital currency and how digital currencies are used

Is a currency that only exists electronically

Used for:

• Online transactions,

• decentralized payments,

• fast cross-border transfers

Understand the process of blockchain and how it is used to track digital currency transactions

Blockchain: A digital ledger consisting of a time-stamped series of records (blocks) that cannot be altered
Function: Tracks and records digital currency transactions in a secure and transparent way

Describe the processes involved in, and the aim of carrying out, a range of cyber security threats

Brute-force attack – Trying all possible combinations of passwords or encryption keys
Data interception – Capturing data as it is being transmitted
Distributed denial of service (DDoS) – Overloading a server or network with traffic to make it unavailable
Hacking – Unauthorized access to or manipulation of systems
Malware – Malicious software including: Virus, Worm, Trojan horse, Spyware, Adware, Ransomware
Pharming – Redirecting users from a legitimate website to a fake one
Phishing – Fraudulent emails or messages trying to obtain sensitive data
Social engineering – Manipulating people into giving up confidential information

Explain how a range of solutions are used to help keep data safe from security threats

Access levels: Users have different permissions based on roles
Anti-malware: Software that detects and removes malicious software (anti-virus, anti-spyware)
Authentication: Verifying identity using:
Username and password
Biometrics
Two-step verification
Automating software updates: Ensures systems are patched against the latest threats
Checking spelling and tone: Identifies phishing and suspicious communication
Checking the URL in a link: Helps spot fake or misleading websites
Firewalls: Filters incoming and outgoing traffic to block harmful connections
Privacy settings: Controls how much personal data is shared on apps and websites
Proxy servers: Intermediary servers that help filter, log, and anonymize internet traffic
SSL (Secure Socket Layer): Security protocol that encrypts data transferred between user and serv