Unit 2 AP Comp Sci Principles

Key Concepts

  1. History of the Internet

    • Why was the Internet created?

      • To establish a secure, decentralized communications network for the military. The earliest version was called ARPANET.

  2. Computing Basics

    • What is a computing device?

      • A machine that can run a program.

  3. Protocols

    • What is a protocol?

      • A standard set of rules governing how data is formatted, transmitted, and received.

    • Importance of Protocols:

      • Facilitate communication between different devices.

      • Form the basis of the internet’s functionality and scalability.

  4. Bandwidth

    • What is bandwidth?

      • The maximum amount of data that can be transmitted across a network in bits per second.

    • Effects of Bandwidth Changes:

      • Increased Bandwidth: More data transmitted simultaneously; improved speeds and streaming.

      • Decreased Bandwidth: Slower speeds and increased buffering.

  5. Fault Tolerance and Redundancy

    • What is fault tolerance?

      • The ability of a system to continue operating despite the failure of one or more components.

    • What is redundancy?

      • A strategy for achieving fault tolerance by duplicating important components in a system.

  6. Scalability

    • What is scalability?

      • The ability for a system to grow and accommodate more users or devices.

  7. Data Transmission

    • What is a path?

      • The route that data packets take from the source to the destination.

Communication Analogy

  • How do two devices communicate over the internet?

    • Sending a letter through the postal system:

      1. Sender writes a letter (data) and addresses it (with IP address).

      2. The letter goes to the local post office (router).

      3. The post office routes it through sorting centers (internet infrastructure).

      4. The letter reaches the recipient's post office and is delivered to the addressee (destination device).

Internet Protocols and Addresses

  1. IP Address

    • What is an IP address?

      • A unique numerical identifier for each device on a network.

    • Uses of IP Address:

      • Identification and location addressing for data routing.

  2. IPv4 and IPv6

    • What is IPv4?

      • The standard human-readable IP address format.

    • What is IPv6?

      • A newer, larger address format to accommodate the shortage of IPv4 addresses.

    • Benefits of IPv6:

      • Provides an almost unlimited number of IP addresses.

  3. TCP vs. UDP

    • TCP (Transmission Control Protocol):

      • Connection-oriented, reliable, ensures ordered delivery with error checking.

    • UDP (User Datagram Protocol):

      • Connectionless, faster, prioritizes speed over reliability with no guarantees.

DNS and Data Packaging

  1. How does DNS work?

    • Translates human-readable domain names into IP addresses. When a URL is entered, a DNS server is queried for the corresponding IP address.

  2. What is a packet?

    • A unit of data transmitted over a network.

    • Metadata in a packet includes:

      • Source and destination IP addresses

      • Protocol type (TCP, UDP)

      • Sequence number (for TCP)

      • Port numbers

      • Checksum for error detection

      • Time-to-live (TTL) value

  3. Web Communication Protocols

    • What protocol is used to retrieve information from a website?

      • HTTP (Hypertext Transfer Protocol) or HTTPS (HTTP Secure).

  4. HTTP Methods

    • What is a "GET" request?

      • An HTTP method to request data from a specified resource without modifying server data.

    • What is a "POST" request?

      • An HTTP method used to send data to a server to create/update a resource.

  5. Difference between HTTP and HTTPS

    • HTTPS provides a secure connection through encryption, protecting data integrity and confidentiality during transmission.