AP CSP Day 47: Internet Structure | Cycle 2

Key Concepts

The hierarchical structure of the internet includes edge networks (homes, businesses), regional networks, and backbone networks connected by high-capacity links. Routing tables stored in routers determine the next hop for each packet based on destination IP address. AP CSP Cycle 2 internet structure questions challenge students to analyze network topology diagrams, identify bottlenecks where a single router or link carries all traffic between two parts of the network, and evaluate how adding a connection would improve fault tolerance or reduce latency. Distinguishing between local and wide-area network concerns is a deeper exam skill.

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Internet Topology: Bottlenecks and Redundancy

Bottleneck Nodes

A bottleneck in a network is a node or link through which all traffic between two regions must pass. If this single point fails, all connectivity between those regions is lost, regardless of how redundant the rest of the network is.

Mesh vs. Hub-and-Spoke

A mesh topology connects every node to multiple others, providing high redundancy. A hub-and-spoke topology connects all nodes through a central hub, which becomes a single point of failure. The internet uses a mesh topology at the backbone level for maximum resilience.

Common Trap: Assuming that a highly connected network has no single points of failure. If all connections between two regions pass through one router, that router is a single point of failure regardless of overall connection density.
Exam Tip: To find bottlenecks, look for nodes or links that appear on every path between two specific regions of the network. Remove that element mentally and check whether any nodes become unreachable.
Big Idea 4: Computing Systems & Networks
Cycle 2 • Day 47 Practice • Hard Difficulty
Focus: Internet Structure

Practice Question

The Internet was designed with no single central authority controlling all data flow. Which of the following are advantages of this decentralized design?

I. If one part of the network fails, other parts can continue functioning independently.
II. No single organization can control or censor all Internet traffic globally.
III. Every data transmission always takes the shortest possible path between source and destination.

Why This Answer?

Statement I is true: decentralization means failures are localized and don't bring down the entire network. Statement II is true: no central authority means no single point of control. Statement III is false: routing considers factors like congestion, policies, and available paths — packets may not take the shortest route.

Why Not the Others?

B) Statement II is also a genuine advantage of decentralization. C) Statement III is false — routing is dynamic and considers multiple factors. D) Statement III is false, making "all three" incorrect.

Common Mistake
Watch Out!

Students assume data always takes the optimal or shortest path. In reality, Internet routing is dynamic and influenced by congestion, network policies, cost, and available bandwidth.

AP Exam Tip

The Internet's decentralized design provides two key benefits: resilience (no single point of failure) and openness (no single point of control). Routing efficiency is not guaranteed.

Keep Practicing!

Consistent daily practice is the key to AP CSP success.

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