Big Idea 4 Unit Test: Computing Systems and Networks
📝 10 questions🎯 AP exam difficulty✅ Auto-scored
📋 Unit Test instructions
This unit test covers all of Big Idea 4: the Internet, fault tolerance, and parallel and distributed computing.
Answer all 10 questions, then press Submit test. You will see your score, which questions you missed, and the correct answer with an explanation. Passing is 70%, the AP benchmark. You can retake it.
0 of 10 answered
Question 1 of 10Internet vs Web
A student claims, "The Internet and the World Wide Web are two names for the same thing." Which statement most accurately corrects or supports this claim?
Answer: D. Correct. The Internet is the underlying network of networks; the Web is just one application (hyperlinked pages) built on top of it, along with services like email.
Question 2 of 10Protocols
Two computers made by different companies, running different operating systems, exchange data reliably across the Internet. According to the AP CSP framework, what makes this possible?
Answer: C. Correct. Protocols are agreed-upon rules; IP handles addressing and routing while TCP provides reliable, ordered delivery, so any devices that follow them can communicate.
Question 3 of 10Packets and routing
A large file is sent from one computer to another across the Internet. Which statement best describes how the data travels?
Answer: B. Correct. Data is broken into packets that route independently, may arrive out of order, and are reassembled using sequencing information at the destination.
Question 4 of 10Bandwidth
A network advertisement says a connection has "high bandwidth." In AP CSP terms, what does bandwidth measure?
Answer: B. Correct. Bandwidth is the maximum amount of data sent per unit of time (a rate, often bits per second), not the travel time of a single bit.
Question 5 of 10Redundancy
Which statements about redundancy in a network are correct?
I. Providing multiple paths between devices makes the network more fault tolerant
II. If one path or router fails, packets can be rerouted along another path
III. Adding redundancy always lowers the total cost of building the network
Answer: D. Correct. Redundancy (multiple paths) improves fault tolerance and lets packets reroute when a path fails, but it generally increases cost rather than lowering it, so III is false.
Question 6 of 10Fault tolerance
A network is designed so that data between two cities can travel over several independent paths. One night a major router on the usual path goes down, yet messages still get through. Which idea does this best illustrate?
Answer: A. Correct. Redundant, independent paths let packets reroute around the failed router, which is exactly what makes the network fault tolerant.
Question 7 of 10Single point of failure
In a certain network, every message between the east and west regions must pass through one central router with no alternate path. What is the most accurate assessment of this design?
Answer: C. Correct. With no alternate path, that one router is a single point of failure, and its outage severs communication between the regions.
Question 8 of 10Sequential vs parallel
Which statement correctly distinguishes sequential, parallel, and distributed computing?
Answer: A. Correct. Sequential runs one step at a time, parallel performs operations simultaneously (often on multiple processors), and distributed spreads a problem across multiple networked computers.
Question 9 of 10Speedup calculation
A task takes 60 seconds to run sequentially. It consists of a 20-second portion that cannot be parallelized and a 40-second portion that can be split perfectly across processors. With enough processors, the parallel portion is reduced to 10 seconds. What is the speedup of the parallel solution compared with the sequential solution?
Answer: B. Correct. Speedup = sequential time / parallel time = 60 / (20 + 10) = 60 / 30 = 2.0. The unavoidable sequential part limits the speedup.
Question 10 of 10Limits of parallelism
A program has a part that must run sequentially and a part that can be parallelized. As a team adds more and more processors, they notice the speedup improves less and less with each additional processor. What is the best explanation?
Answer: A. Correct. Only the parallel portion benefits from more processors; the fixed sequential part remains, so speedup approaches a limit and gains diminish (diminishing returns).
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