Network Devices (College Board AP® Computer Science Principles): Revision Note
Computing systems & networks
What is a computing device?
A computing device is a physical object that can run a program (e.g., computers, tablets, smartphones, sensors, smart appliances)
A computing system is a group of computing devices and programs working together for a common purpose
Computing systems enable collaboration by allowing multiple users and devices to share resources and work together on tasks
Computing hardware and infrastructure
Hardware refers to the physical components of a computing device (processors, memory, storage, input/output devices)
Network infrastructure is the collection of hardware, software, and connections that enables devices to communicate
Devices are interconnected through wired or wireless connections, forming networks that allow data to be shared
Term | Definition | Example |
|---|---|---|
Computing device | Physical object that can run a program | Smartphone, laptop, server |
Computing system | Devices and programs working together for a purpose | School network with shared printers and storage |
Network | Interconnected devices that communicate and share data | Home Wi-Fi connecting a phone, laptop, and smart TV |
Network paths & routing
How does data travel through a network?
Data travels from a sender to a receiver along a path through the network
A path is the sequence of directly connected computing devices that data passes through from sender to receiver
Data does not always take the same path; the route can change depending on network conditions
Routing
Routing is the process of finding a path from sender to receiver through the network
Routers examine the destination of each piece of data and forward it along the most appropriate path
Multiple paths may exist between any two devices on a network, providing flexibility and reliability
Bandwidth & data transfer
What is bandwidth?
Bandwidth is the maximum amount of data that can be sent through a connection in a fixed amount of time
Bandwidth is measured in bits per second (bps), with common units including kilobits (Kbps), megabits (Mbps), and gigabits (Gbps)
Bandwidth represents the maximum capacity of a connection, not the actual speed of data transfer at any given moment
Data transfer limitations
The actual rate of data transfer may be lower than the bandwidth due to network congestion, distance, or hardware limitations
When multiple devices share the same connection, the available bandwidth is divided among them
Higher bandwidth allows more data to be transferred in less time, but does not guarantee faster transfer if other bottlenecks exist
Examiner Tips and Tricks
Bandwidth exam questions often test whether you understand that it is the maximum capacity, not the guaranteed speed; if a question describes shared or congested connections, the actual transfer rate will be lower than the bandwidth.
For the CPT, if your program sends or receives data over a network (e.g., using an API), understanding how bandwidth and routing affect performance can help you explain design decisions in your written response.
Worked Example
A school's internet connection has a bandwidth of 100 Mbps. If 50 students are streaming video simultaneously and sharing the connection equally, what is the maximum bandwidth available per student?
(A) 100 Mbps
(B) 50 Mbps
(C) 2 Mbps
(D) 5000 Mbps
[1]
Answer:
(C) 2 Mbps [1 mark]
100 Mbps divided equally among 50 students gives each student a maximum of 2 Mbps of bandwidth
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