Advanced Placement (AP) Computer Science

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Enhance your readiness for the AP Computer Science exam with insightful quizzes. Deepen your understanding and master key concepts as you prepare for a successful test experience!

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Which of the following is NOT a component of the IP hourglass model?

HTTP
UDP
DNS
TCP

The correct answer is: DNS

The IP hourglass model illustrates how the Internet Protocol (IP) serves as a foundation for various other protocols and applications. At the narrowest point of the hourglass, IP sits, supporting a wide range of transport layer protocols, such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). Above IP, you find application layer protocols, including HTTP (Hypertext Transfer Protocol) and DNS (Domain Name System). The correct answer indicates that DNS, while a critical application layer protocol used to translate domain names into IP addresses, is not a foundational component like IP or the transport layer protocols TCP and UDP. Thus, DNS does not form a part of the hourglass structure that highlights how protocols depend on IP. HTTP and UDP are relevant components within the model, showcasing how different applications and transport methods build upon the foundational structure that IP provides. By understanding the hourglass model, you can better grasp the layered architecture of the Internet and how protocols interact within that framework.