AP CSP Practice: Internet & Fault Tolerance

Big Idea 4: Computing Systems and Networks
Day 5 Practice • AP CSP Daily Question
🎯 Focus: Internet and Fault Tolerance

Practice Question

The internet was designed to be fault-tolerant so that communication could continue even when parts of the network fail.
Which of the following is the PRIMARY reason the internet is fault-tolerant?
What This Tests: Big Idea 4 covers how the internet works, including its design as a fault-tolerant network that can route around failures.

Why B is Correct

The internet is fault-tolerant because of redundancy—there are multiple paths between any two devices. If one route fails, data can travel through alternative paths.

Key concepts:

  • Redundant paths: Multiple routes exist between points
  • Packet switching: Data is broken into packets that can take different routes
  • Dynamic routing: Routers automatically find working paths
  • Decentralized design: No single point of failure

Visualizing Redundancy

        [Router A]----[Router B]
        /      \      /      \
 [You]--        ----          --[Website]
        \      /      \      /
        [Router C]----[Router D]

If Router A fails, your data can still reach
the website through Router C → D → B

Common Mistakes

Mistake: Answer A - Encryption

Encryption protects data privacy and security, but it doesn't make the network fault-tolerant. A secure message still can't be delivered if there's no working path.

Mistake: Answer C - Central server

A single central server would be the OPPOSITE of fault-tolerant! If that server failed, the entire network would stop working. The internet is deliberately decentralized.

Mistake: Answer D - Guaranteed uptime

ISPs cannot guarantee uptime because failures happen. Fault tolerance means the system can work around failures, not prevent them entirely.

💡 AP Exam Tip

Remember the key internet design principles: redundancy (multiple paths), packet switching (data split into pieces), and decentralization (no single point of control). These all contribute to fault tolerance.

Difficulty: Easy • Time: 1-2 minutes • Topic: 4.1 The Internet

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