Internet Basics
Big Idea 4 — Computing Systems & Networks · ~8–11 questions on the AP exam
What This Lesson Covers
This is the highest-yield Internet content on the AP CSP MCQ. Click through each section, try the practice questions, and pay attention to the misconceptions — those are exactly what the wrong-answer choices test.
- Internet vs. World Wide Web (most-tested distinction in this unit)
- Packet switching & routing metadata
- Fault tolerance & redundancy
- Protocols: TCP, IP, UDP, HTTP/HTTPS, DNS
- IPv4 → IPv6 and scalability
- Bandwidth vs. latency, open standards
1. Internet vs. World Wide WebEK CSN-1.D
This is the single most-tested distinction in Big Idea 4. They are not the same thing.
The World Wide Web is a service that runs on the Internet — a system of linked pages, programs, and files accessed via web browsers using HTTP/HTTPS.
Other things that use the Internet (but are not the Web)
- Email (SMTP, IMAP)
- Video streaming and gaming services
- Messaging apps
- File transfer (FTP)
Which best describes the relationship between the Internet and the World Wide Web?
2. Packet SwitchingEK CSN-1.C
When data is sent over the Internet, it does not travel as one continuous stream along a fixed path. It is split into packets that travel independently.
How it works (and what the exam tests)
- Data is broken into small packets.
- Each packet carries routing metadata — source address, destination address, sequence number, and other control info — alongside its chunk of data.
- Packets travel independently, possibly along different paths.
- They may arrive out of order.
- The receiver reassembles them in the correct order using the sequence info.
A large file is sent from one computer to another over the Internet. Which best describes how the data travels?
In addition to the chunk of data being sent, what does each packet contain?
3. Fault Tolerance & RedundancyEK CSN-1.E
The Internet is designed to keep working when parts of it fail. Two terms you must know verbatim:
| Term | Meaning |
|---|---|
| Fault tolerance | The ability of a system to continue functioning when some of its components fail. |
| Redundancy | Including extra components (such as alternate paths) that can be used if a primary component fails. |
| Dynamic routing | Routers find new paths in real time when a path fails or becomes congested. |
Which of the following best explains why the Internet is considered fault tolerant?
4. Protocols Speed-RoundEK CSN-1.B / CSN-1.C
A protocol is an agreed-upon set of rules for how computers communicate. The exam expects you to recognize each of these by name and one-line job:
| Protocol | One-line job |
|---|---|
| IP | Addresses each device and routes packets from source to destination across networks. |
| TCP | Splits data into packets, reassembles them in order at the destination, and re-sends any that are lost. Reliable. |
| UDP | Faster, lighter alternative to TCP that doesn't guarantee order or delivery. Used for streaming/gaming where speed > reliability. |
| HTTP | The application protocol used by the World Wide Web to request and serve web pages. |
| HTTPS | HTTP plus encryption (via TLS). Protects data in transit between browser and server. |
| DNS | Translates human-readable domain names (like wikipedia.org) into IP addresses. It does not deliver the website. |
A web browser needs to find the IP address that corresponds to wikipedia.org. Which protocol performs this lookup?
Which two protocols work together to break a message into packets, route them across networks, and reassemble them in order at the destination?
5. IPv4 → IPv6 (Scalability)EK CSN-1.B
An IP address is a numerical label assigned to each device on a network. There are two versions in use:
| Version | Address space | Why it matters |
|---|---|---|
| IPv4 | ~4.3 billion addresses (32 bits) | The original. Running out of unused addresses. |
| IPv6 | ~3.4 × 1038 addresses (128 bits) | Designed to scale to vastly more connected devices. |
What is the primary reason the Internet is transitioning from IPv4 to IPv6?
6. Bandwidth vs. LatencyEK CSN-1.A
| Term | Plain-English meaning | Analogy |
|---|---|---|
| Bandwidth | Maximum amount of data that can be transmitted per unit of time (capacity). | Width of a pipe. |
| Latency | The delay between sending and receiving — how long one packet takes to arrive. | Length of the pipe. |
A network can be high-bandwidth but high-latency (lots of data eventually, but each piece takes a while to arrive) or low-bandwidth but low-latency (responses come back quickly but you can't pump much through).
A user reports that videos take a long time to start playing, even though once they begin, they play smoothly in high quality. The "long time to start" is best described as a problem of:
Heads up: MAC Addresses Are Not on the AP CSP Exam
A few of you asked about MAC addresses on the survey. Good question — but here's the deal:
MAC addresses are real and important in networking, but they are not part of the AP CSP Course and Exam Description. The exam's networking content covers IP addresses, DNS, TCP, UDP, and HTTP/HTTPS — that's it for protocols and identifiers. MAC addresses are a CompTIA/Network+ topic.
Translation: Don't spend study time on MAC addresses for this exam. Spend it on the Internet vs. WWW distinction and packet switching.
Misconception Lightning Round
These are statements that sound right but are wrong — and the wrong answer choices on the AP MCQ are built from these. Click True or False:
"HTTPS guarantees that a website is trustworthy and safe."
"An IP address uniquely and permanently identifies a specific person."
"DNS delivers the contents of a webpage to your browser."
"If a single network cable or router on the path between two computers fails, all communication between them stops."
"Bandwidth and latency are two words for the same thing."
What's NOT on the AP CSP Exam
Don't waste study time on these — they sound network-y but the AP CSP exam doesn't test them:
- OSI 7-layer model and layer numbers Out of scope
- Subnetting, CIDR notation, subnet masks Out of scope
- Specific port numbers (80, 443, 53, etc.) Out of scope
- NAT, BGP, ARP, ICMP details Out of scope
- The TLS handshake mechanics Out of scope
- Memorizing exact IPv4 dotted-decimal or IPv6 hex syntax Out of scope
- MAC addresses Out of scope
More Info — Trusted Sources to Verify or Go Deeper
Everything on this page is drawn from these sources. If you want to double-check anything or read more deeply, these are the references your teachers and the College Board treat as authoritative.
- College Board AP Central — AP CSP Course Page — Official source. The Course and Exam Description (CED) PDF lists the exact Essential Knowledge statements (the EK codes you saw in this lesson).
- AP CSP Course and Exam Description (PDF) — The official curriculum framework. Big Idea 4 (Computer Systems and Networks) is the relevant section for this lesson.
- Khan Academy — AP CSP: The Internet — Free video lessons and practice questions aligned to the AP CSP framework.
- Mobile CSP Textbook — Communication Through the Internet — Open-source textbook used by AP CSP teachers nationwide.
- Internet Society — How the Internet Works — Neutral, authoritative explainer maintained by one of the Internet's standards-setting organizations.
- ICANN — What is DNS? — From the organization that actually coordinates DNS at the global level.