AP Computer Science P Unit 4 Cheatsheet: Computer Systems and Networks

Computing device: Physical artifact that runs a program (computers, tablets, servers, routers, smart sensors).

Computing system: Group of computing devices and programs working together for a common purpose.

Computer network: Interconnected computing devices capable of sending or receiving data.

Path: Sequence of directly connected devices from sender to receiver.

Routing: Process of finding a path from sender to receiver.

Bandwidth: Maximum amount of data sent in a fixed time, measured in bits per second.

Fault tolerance: System can support failures and continue functioning.

Redundancy: Inclusion of extra components to mitigate failure if others fail.

Network redundancy example: Multiple paths between any two connected devices.

How it works: If a device or connection fails, data is rerouted via an alternative path.

Trade-off: Redundancy requires additional resources but provides reliability and scalability benefits.

Why it matters: Complex systems fail unexpectedly and often in groups; fault tolerance allows continued network use.

Redundancy identification: Look for multiple paths, backup components, or alternative routes. This is redundancy.

Fault tolerance vs. redundancy: Redundancy is the mechanism; fault tolerance is the result (system keeps working).

Failure scenarios: If asked how a system handles a failed device, answer: data reroutes via alternate path (if available).

Cost-benefit: Redundancy requires extra resources but improves reliability by providing fault tolerance. Be ready to explain this trade-off.