AP Classroom Completed Assignments (10/17)

The AP Classroom Completed Assignments for this week.

4.1

  • Computers used to be very large, and take up full rooms because of how big they were
  • Computers got smaller as time progressed
  • Computers needed to connect to each other in order to work
  • Routers were created to help computers work faster and connect to each other
  • Routers also help information find its way from the sender to the receiver
  • Packets are small amounts of data sent over a network, which include data, source information, and destination information
  • Packets are sent by the sender and received by the receiver
  • Computer systems are groups of computers working together to achieve a common goal
  • Computer networks are a group of interconnected devices that send and receive data
  • Packet switching is when a message/file is broken up into packets and sent in any order, then reassembled by the receiving device
  • A path is the network between two computing devices, and is a sequence of directly connected computing devices
  • Bandwidth (measured in bits per second (BPS)) is the maximum amount of data that can be sent in a fixed amount of time on a computer network

4.2

  • OSI (Open Systems Interconnect) - The layers needed to go through to communicate (Application, Presentation, Session, Transport, Network, Data Link, Physical)
  • TCP (Transmission Control Protocol) - Establishes a common standard for how to send messages between devices on the internet (Application, Transport, Internet, Network Access)
  • There are many different protocols, standards, and etc. used in the Application/Transport levels, such as HTTP and DNS (OSI layers 3-7)
  • Internet Engineering Task Force (IETF) manages the development of internet standards via written technical discussions (Requests for Comments, RFC) in an open and collaborative process
  • Network Access Layer:
    • Pulls the 1’s and 0’s from a wire or radio wave, focused on hardware and protocols that carry 1’s or 0’s
    • Each NIC has a unique address associated with it (Media Access Control (MAC) Address), used for local hops
  • Network Access/Internet Layer Data Transmission:
    • A packet contains data that is being transmitted as well as metadata containing iniformation used for routing information
  • Internet Layer:
    • Internet was designed to be scalable/able to change in size and scale to meet new demands
    • Local Area Network (LAN) physically connects, limited by hardware and physics, 1 to hundreds of systems
    • Intranet - LANs connected by routers within an organization, hundreds to thousands of systems
    • Autonomous Systems (AS) - Large intranets linked together under the control and policies of major organizations, tens of thousands of systems
    • The internet, millions of systems made of Autonomous Systems linked together
  • Transport Layer:
    • TCP does error checking and error recovery, so it is slower
    • UDP performs error checking, but discards erroneous packets
    • Open standards and protocols enable different manufacturers and developers to build hardware/software that can communicate with the hardware/software on the rest of the internet
  • Internet/Transport Layers:
    • Reliability -
      • Reliability - Sender gets a receipt back, can be resended as needed
      • Transport Control Protocol (TCP)
      • Unreliability - Send and forget, User Datagram Protocol (UDP)
    • Purpose “Port” - Number assigned to an application or survice
    • 3 targets can be addressed using IP:
      • Unicast - A specific device, internet wifde access; TCP is used
      • Multicast - A group of devices, it is specific range of IP addresses with internet wide access, UDP is used
      • Broadcast - All devices, LAN-wide, data stops at the router, and a UDP is used
  • Application Layer:
    • Web servers - programs running on machines connected to the internet; provides web pages to clients, links to other pages using Uniform Resource Locations (URLs)
    • Domain Name Service (DNS) - Applications that translate a human readable url to an IP address, holds a database of mapping of names to IPs
  • Ethernet is the most popular way to access a network