A network is two or more devices connected so they can communicate and share data or resources.

Performance is how quickly and reliably data moves and how responsive network services feel.

Exam link: connect the factor to its effect. For example, more users sharing the same bandwidth can mean less capacity available to each user.

The model describes the computers’ roles. A “client” is the device requesting a service; a “server” is the device providing it.

Standalone computers can be connected into a LAN using network hardware and a transmission medium.

In a typical small LAN, devices use a NIC to connect by cable to a switch, or by Wi‑Fi to an access point. A router links the LAN to other networks.

The Internet is a worldwide collection of interconnected computer networks. It carries many services; the World Wide Web is one service that uses the Internet.

What happens when a website is requested?

1. You enter a URL. Its domain name identifies the website; the rest of the URL may identify a page or resource.
2. DNS (Domain Name System/Service) uses multiple Domain Name Servers in a distributed hierarchy. It looks up the domain name and returns its IP address.
3. The client device uses that IP address to contact the web server hosting the site.
4. The web server responds with the requested web page or other resource for the client to display.

Hosting and server services

• Hosting: a host stores a website’s files on a server connected to the Internet and makes them available to clients.
• Web server: provides web pages or other web resources when clients request them.
• File server: provides central file storage and retrieval to authorised clients.
• Client: requests and uses a service, such as a browser requesting a page or a computer retrieving a shared file.

Cloud computing is the provision of computing services over a network, usually the Internet, from remote servers. The service may provide storage, software or processing power.

Examples include online file storage, browser-based software and remote processing services.

A topology describes how devices and links are arranged in a network.

A star is common for a small wired LAN. A mesh is useful where resilience and alternative routes are important. Choose based on the scenario’s needs and trade-offs.

Scenario: A school needs 28 wired desktop computers in one lab, Wi‑Fi for tablets, shared lesson files and a public website. Staff in a second town also need access to the school’s network services.

1. Which network type connects computers inside the school site? Which type links the two towns?
2. Which devices and media would you use to connect the lab desktops and tablets?
3. Which network model fits shared lesson files? What would the client and server do?
4. How would a student’s browser find the public website from its domain name?
5. Would a star or mesh topology suit the lab? Give one benefit and one drawback.
6. Name one performance issue that may occur when many students use the network at once.

Devices can join a network using a physical cable or a wireless signal. Compare the benefits and drawbacks, then recommend a connection that fits the scenario.

Encryption transforms readable data into ciphertext using a key. A party with the right key can decrypt it. Encryption helps protect the confidentiality of data travelling over a network.

For example, HTTPS encrypts web traffic between a browser and a website. This helps prevent intercepted network traffic from being read easily.

Addresses help deliver data to the right destination. IP addresses support communication between networks; MAC addresses identify a network interface for delivery on a local link.

The specification does not require static/dynamic or public/private IP address categories.

A standard is an agreed technical specification. Standards provide shared rules so hardware and software from different manufacturers can interact and exchange data.

Without agreed standards, devices or programs could use incompatible signals, formats or procedures. You need to understand the purpose of standards; memorising individual standard names is not required here.

A protocol is a set of rules for transferring data. Different protocols are designed for different purposes.

Layers split network communication into manageable jobs. As data is sent, each layer adds information needed for its task; the receiving device processes the layers in reverse. This modular approach makes systems easier to design, update and troubleshoot, and lets protocols work together through agreed interfaces.

The four-layer TCP/IP model is one teaching example:

You need to understand how layers are used and their benefits. You do not need to memorise the names and functions of each TCP/IP layer, or how Ethernet, Wi-Fi and Bluetooth work internally.