AP CSP Day 20: Internet Protocols

Key Concepts

Protocols are agreed-upon rules that govern how devices communicate over a network. TCP (Transmission Control Protocol) ensures reliable, ordered delivery by requiring acknowledgment of received packets, while UDP sends packets without confirmation for speed-critical applications. HTTP and HTTPS handle web page requests, with HTTPS adding encryption for security. AP CSP exam questions test whether students can match protocols to their purposes and understand that the internet's layered protocol stack allows devices from different manufacturers to communicate seamlessly.

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Internet Protocols

What Is a Protocol?

A protocol is a set of agreed-upon rules that allow devices to communicate. Without protocols, a device from one manufacturer could not communicate with a device from another, because they would have no shared language or format.

Key Protocols to Know

HTTP transfers web pages (unencrypted). HTTPS adds encryption for security. TCP ensures reliable, ordered packet delivery with acknowledgment. UDP prioritizes speed over reliability. DNS translates domain names like 'google.com' into IP addresses.

Common Trap: Thinking HTTPS encrypts everything about a connection. HTTPS encrypts the content of messages but not the IP addresses of sender and receiver, which remain visible to network observers.
Exam Tip: Know the purpose of each major protocol and the tradeoff it makes. TCP: reliable but slower. UDP: fast but no guarantee of delivery. HTTPS: secure but computationally more expensive than HTTP.
Big Idea 4: Computing Systems & Networks
Cycle 1 • Day 20 Practice • Medium Difficulty
Focus: Internet Protocols

Practice Question

Which of the following best describes the role of TCP (Transmission Control Protocol) in Internet communication?

Why This Answer?

TCP provides reliable, ordered delivery of data. It numbers packets with sequence information, verifies receipt through acknowledgments, and requests retransmission of any lost or corrupted packets.

Why Not the Others?

A) IP addresses are managed by protocols like DHCP and the IP protocol itself, not TCP. C) Encryption is provided by TLS/SSL, which operates on top of TCP. B) Physical cable routing is an infrastructure concern, not a protocol function.

Common Mistake
Watch Out!

Students confuse the roles of TCP and IP. TCP handles reliable delivery and ordering. IP handles addressing and routing. They work together as TCP/IP.

AP Exam Tip

Remember the division of labor: TCP = reliable, ordered delivery. IP = addressing and routing. They are separate protocols that work together.

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