Computer Science Principles: Internet Architecture, Protocols, and Networking

Comprehensive practice flashcards covering AP Computer Science Principles topics on Internet protocols, addressing (IPv4 and IPv6), DNS, HTTP/HTTPS, routing, redundancy, computing networks, TCP, and UDP based on lecture notes.

Who is credited as the inventor of the Domain Name System (DNS)?

Paul Mockapetris.

What is the primary function of the Domain Name System (DNS)?

DNS maps human-readable domain names (such as Amazon.com) to their corresponding IP addresses on a network.

How does the Domain Name System (DNS) contribute to the scalability of the Internet?

When new servers join the Internet, they register their IP addresses with the DNS server, allowing the network to grow without requiring users to memorize new numerical IP addresses.

How does a user's device connect to a DNS server without the user memorizing the DNS server's IP address?

The user's Internet Service Provider (ISP) stores and remembers the IP address of the DNS server.

What are the intended purposes of the Top-Level Domains (TLDs) .com, .net, .edu, .org, .mil, and .gov?

.com is for for-profit business entities; .net is for network technology companies like ISPs; .edu is for American educational institutions; .org is for nonprofit organizations; .mil is restricted to U.S. military branches; and .gov is restricted to American federal governmental agencies.

What are the three hierarchical levels of the Domain Name System structure?

1) Root Level (root domain, the highest hierarchical level of the Internet), 2) Top-Level Domain Level (TLD), and 3) Subdomain Level.

What is a subdomain?

An additional section of a main domain name created to organize and navigate to different sections of the main website (e.g., drive.google.com).

What is HTML?

HTML (Hypertext Markup Language) is the standard markup language used for creating web pages.

How does the World Wide Web differ from the Internet?

The World Wide Web is a system of linked pages, programs, and files that is accessed using the Internet, whereas the Internet is the physical network of connected devices and infrastructure.

What is Hypertext Transfer Protocol (HTTP)?

HTTP is an application protocol for distributed, collaborative, hypermedia information systems that allows users to request and share pages and files on the World Wide Web.

How does a web browser display a web page using HTTP?

Web pages are delivered to the browser as plain text containing formatting directions and image locations; the browser interprets the text, formats the page, requests any required images, and places them on the page.

What is HTTPS and how does it ensure security?

HTTPS (Hypertext Transfer Protocol Secure) is the secure version of HTTP that uses encrypted communication via TLS/SSL protocols to protect data transfer between a client browser and a server.

What is a Website Security Certificate?

A digital stamp of approval issued by an industry-trusted third party known as a Certificate Authority (CA) confirming that a website is using proper encryption protocols.

What are TLS and SSL?

TLS (Transport Layer Security) and SSL (Secure Sockets Layer) are security protocols that encrypt data transmitted between a browser and a website.

What are the primary layers of abstraction on the Internet from highest to lowest?

1) World Wide Web (HTTP, HTTPS, DNS), 2) Pure Internet (TCP, UDP, IP, Routing), and 3) Physical Layer (Wires, Cables, WiFi transmitting binary sequences of 1s and 0s).

What is a router?

A specialized type of computer that forwards data packets across a network.

What is redundancy in network design?

The inclusion of extra components (such as multiple distinct paths between any two connected devices) so that a system can continue to function even if individual components fail.

What does it mean for a network to be fault tolerant?

A system is fault tolerant if it can continue to function even in the event of individual component failures.

How does network redundancy relate to fault tolerance?

The greater the redundancy in a network, the greater its fault tolerance.

Which utility command can be run in a computer terminal to trace the network path taken to reach a destination server?

traceroute (or tracert in Windows Command Prompt).

What are the five essential tasks performed by the Internet Protocol (IP)?

1) Assigning unique IP addresses to devices, 2) Splitting messages into smaller packets, 3) Labeling packets with metadata, 4) Sending packets through the network across available paths, and 5) Reassembling packets into original messages at the destination.

What is the difference between an Open Protocol and an Open Standard?

An Open Protocol is a set of publicly available rules that specify how devices communicate with each other, whereas an Open Standard is a technical standard that is publicly available and free for anyone to use.

What is metadata?

Metadata is data that describes other data, such as packet numbering, source IP address, and destination IP address included with transmitted network packets.

What are the address structure and capacity of IPv4?

IPv4 uses a 32-bit numerical address divided into four sections ranging from 0 to 255 (e.g., 172.217.9.78), providing $256^4 = 4,294,967,296$ unique addresses.

Why was IPv6 developed, and what is its capacity?

IPv6 was created because IPv4 does not have enough unique addresses for all Internet-connected devices; it uses 128 bits written as 8 groups of hexadecimal numbers, providing approximately 340 undecillion possible addresses.

How can over 13 billion devices connect to the Internet when IPv4 only provides around 4.3 billion unique addresses?

Organizations and households use a single unique external IP address for outside communication while reusing internal IP addresses within local private networks.

What are the three core 'C' requirements needed to communicate over the Internet?

Computers, Connections, and Communication Rules.

What is a computing device?

A machine that can run a program, including computers, tablets, servers, routers, and smart sensors.

What is a computing system?

A group of computing devices and programs working together for a common purpose.

What is a computing network?

A group of interconnected computing devices capable of sending or receiving data.

What is a path in a computer network?

The series of connections between computing devices on a network starting with a sender and ending with a receiver.

What is bandwidth?

The maximum amount of data that can be sent through a network connection in a fixed amount of time, usually measured in bits per second ($\text{bps}$).

What factors contribute to the calculated 'cost' of a network path?

Time, money, availability, relationships, and bandwidth.

What is Transmission Control Protocol (TCP)?

TCP is a reliable transport protocol for sending packets that performs error-checking, packet re-ordering, and acknowledgment verification to ensure all packets are received without loss or corruption.

What steps does TCP take on the sender side during data transmission?

1) TCP breaks the message into packets, 2) sets packet metadata, 3) creates a packet checklist, 4) sends packets across the Internet, 5) waits for acknowledgment, and 6) resends any unacknowledged or missing packets.

What steps does TCP take on the receiver side during data reception?

1) TCP logs received packages on a checklist, 2) sends RECEIVED confirmation messages back to the sender, 3) requests missing packets, and 4) reassembles packets in correct numerical order to reconstruct the message.

What is User Datagram Protocol (UDP)?

UDP is a lightweight transport protocol for sending packets quickly with minimal error-checking and no resending of dropped packets.

How do TCP and UDP compare in terms of tradeoffs and application use cases?

TCP prioritizes accuracy over speed by confirming receipt and retransmitting missing data, making it ideal for emails, file transfers, and web browsing; UDP prioritizes speed and low latency over completeness without retransmitting lost packets, making it ideal for video conferencing, live streaming, and online gaming.