Resources:

• https://quizlet.com/543838698/unit-2-ap-computer-science-principles-flash-cards/

• www.code.org

• Lindsey Thorn

• https://quizlet.com/594655681/unit-2-assessment-flash-cards/?funnelUUID=b83df967-dc69-47fd-ae7e-f533f15ad265

Lesson 1: Welcome to the Internet

• Internet Simulator (in this lesson)

  • Similar to the Internet

    • Send Info to others

    • Has a Network

    • Only allows us to contact one person

  • Different to the Internet

    • Can only send text

      Takes a little time to send

What is the Internet? (Video Notes)

• Vint Cerf + Bob Kahn created the Internet

  • result of another experiment called the Arpanent

    • Paul Baren was trying to figure out how to build a communications system that might actually survive a nuclear attack

      

• Baren thought of breaking the messages into blocks and sending the message as quickly as he could through the mess network (Distributed model)

• The Internet is made up of many independently operated networks

  • no one owns the internet

  • no central control

  • fully distributed

  • any device can communicate w any device

    

Major Issues In Society (because of the internet) ==> add tech behind it

• Net Neutrality:

  • principle advocating for all internet traffic to be treated equally => free access to all internet information

    • no discrimination or different charges based on the user, content, site, or platform

  • keeping the digital playing field level for everyone

    • from startups to tech giants

  • prohibits internet service providers from blocking, throttling, or engaging in paid prioritization of lawful content

• Internet Censorship:

  • blocking certain websites because they do not align w a value (could be political)

• Digital Divide:

  • the gap between those who have access to technology, the internet and digital literacy training and those who do not

Lesson 2: Building a Network

• The process of data finding a path from sender to receiver is considered routing.

• When data is routed across a network, how fast the msg arrives is determined by bandwidth.

  • Bandwidth: is the maximum amount of data that can be sent in a fixed amount of time, usually measured in bits per second

    • message arrives quickly: maybe because of high bandwidth (many bits can be sent per second)

    • message arrives slowly: could be due to low bandwidth

• Computing Device: a machine that can run a program, including computers, tablets, servers, routers, and smart sensors (usually singular)

  

  Computing System: a group of computing devices and programs working together for a common purpose

  

  Computing Network: a group of interconnected computing devices capable of sending or receiving data.

  

Lesson 3: Need For Addressing

IP Address + DNS Video Notes

• Connection Chain

  • you → your device →your internet service provider → billions of devices

• Protocol: a well-known set of rules + standards used to communicate between machines

• The Internet has a design philosophy

  • able to absorb + adapt to new internet communication tech

• IP Address (internet protocol)

  • All the different devices on the internet have a unique address

  • address on internet = a number

  • Structure:

• That version of IP Address is called: IPv4

  • makes over 4 billion unique addresses

• 4 Billion is not enough, into the transition to IPv6

  • allows for longer IP addresses

    

  • creates over 340 undecillion unique address

• DNS (Domain Name System)

  • turns domain names into IP addresses, which browsers use to load internet pages.

• DNS servers are connected in a Distributed Hierachy,

• DNA is meant to be open and public communication protocol

  • soooo…lots of cyberattacks

    • DNS Spoofing

    • hacker changes IP address and sends person to hacker website :(((((

    • people use fake websites as real => more problems yay

Lesson 4: Routers and Redundancy

• IP = open protocol that all devices use.

• ensures that all devices can connect to one another simply by knowing their IP address

• The IP addresses of the sender and receiver are converted to binary so that devices know which messages are for them and which device should get a response.

• Messages are sent from router to router →  bouncing between different routers in the network. 

  • Not all messages take the same path to get to their destination.

• When sending multiple messages to the same person→ messages may take different path

Lesson 5: Packets

Intro:

• information traveling over the Internet is divided into many packets

  • these packets travel separately through the network

    • as well as the protocols that allow this process to work even when some packets are lost or delayed

Packets Chart (examples)

The Internet: Packets, Routing & Reliability Video Notes

• Internet is NOT made of direct dedicated connections

• Information goes from one computer to another in a Packet

  • could take different routes to get to different places

• Many types of Infomation can be sent through IP packets

• One image can be broken up into different packets because the entire image might be to big to send in one packet!

• Routers act like traffic monitors to keep the packets moving smoothly

• Having options for paths makes the network fault-tolerant → keeps the key principle of the internet Reliability

• TCP helps with checking and allowing for reliability to occur

• TCP + Router Systems are scalable

• More Routers = More Reliablable

Lesson 6: HTTP and DNS

• IP Addresses can change

• The Domain Name System (DNS) plays a critical role in translating human-readable domain names, like example.com, into IP addresses (e.g., 192.0.2.1), which computers use to identify each other on the Internet.

• How does the DNS solve the problem of translating domain names like example.com into IP addresses?

  • it as able to correspond different names with IP address

• How does the DNS help the Internet scale?

  • DNS Servers are connected in a Distributed Hierachy

    • Able to split up responsibilities for major domains like (.org, .com, .net)

  • DNS = created to be open and public protocol

  • DNS and IP are designed to SCALE, always NO MATTER how much the internet grows

Overall Notes:

• DNS is a network of servers that track the IP addresses of different domain names like example.com

  • When you try to visit a website you first ask the DNS for the IP address of the domain you want to visit.

    • first server may have to ask other servers for this information

  • DNS allows billions of devices to get added to the network w/o putting pressure on one computer/server to know all the IP addresses in the world

• DNS lets you talk to people even if you do not know there IP address

HTTP and HTML Video Notes

• HTTP = Language use to communicate between Web Browers and Servers

  • Mainly made up of Get Requests

    

  • allows the HTML code to get across to the computer

• SSL/TLS = adds layer of security from people tampering or snopping

  ---

• What problem is HTTP solving?

  • When visiting a website, you’re getting sent a file by a server.

  • HTTP solves the problem of how to ask for that file.

  • Your computer and that server communicate using HTTP.

• What is a GET request and what are you requesting?

  • Requests those files or to send data

• How does HTTP rely on the other layers of the Internet?

  • Communications are sent over the Internet so the requests are sent inside TCP/IP packets, over the physical wires of the Internet.

• Why are SSL/TLS, and HTTPS necessary?

  • To secure information online, using HTTP, information would be plain text.??

• What do certificate authorities do and why are they necessary?

  • Ensure when you start a secure connection you're talking to the website you think you're talking to.

Ap Classroom Break Down Notes

• fault-tolerant = redundancy **not that the components are foolproof

  • People do not have access to the internet

    • meaning putting applications for jobs online does not help

• IPv6 allows more more IP address than IPv4 ==> more devices connected to the internet

• Redundancy often allows messages to be sent even if some network devices or connections have failed!

• fault-tolerant: The ability to provide data transmission even when some connections have failed

• internet allows for more perspectives and ability to quickly update content as new info becomes available

• an advantage that online newspapers have over social media sites: ability to provide credibility to the information distributed

  • printed material is more credible

• Both online newspapers and social media sites provide media-rich content at a low cost to the user.

• packets assembled in internet: Each packet contains data to be transmitted, along with metadata containing information used for routing the data.

  • NOT TRUE: packet contains an encrypted version of the data to be transmitted, along with metadata containing the key needed to decrypt the data.

• Lower Bandwidth: will be restricted in the maximum amount of data that they can send and receive per second.

  • WILL NOT

    • be prevented from having fault-tolerant routing on the Internet.

• Data is broken into packets and then reassembled upon arrival.

• Using open protocols ensures that all devices are using the same communication rules but does not necessarily provide fault tolerance.

• Monitoring network traffic can help administrators be aware of component failures but does not necessarily provide fault tolerance.

• Providing high-bandwidth connections can improve transmission speeds but does not provide fault tolerance.

• The message is broken into packets. The packets can be received in any order and still be reassembled by the recipient’s device.

• NO central monitoring computer is used to track and maintain the connections of the Internet.

• Protocols for packets and routing are used so that computers from different manufacturers can communicate in a standard way.

• Packets are pieces of data that travel the Internet. They do not represent the devices themselves.

• Digital certificates are used to verify encrypted keys. They are not assigned to every device connected to the Internet.

• Redundant routing on the Internet is not dependent on the bandwidth of a connection.

• Devices running different operating systems can communicate over the Internet.

• Open standards and protocols cannot be used to allow copyrighted materials to be shared freely.

• As a new device is connected to the Internet, it is assigned an IP address to enable communication on the network.

  

• 3 connections that must be broken or removed in the network before computer E can no longer communicate with computer F

• Computers B and C can communicate with each other without additional computers being aware of the communication.

• Making a computer system fault-tolerant often increases pathways between devices and components, which can increase the possibility of a successful hacking attempt.

• Making a computer system fault-tolerant often requires additional resources, which can increase expenses.

• Making a computer system fault-tolerant increases reliability but may not necessarily increase efficiency.

• Protocols are unable to ensure that all Internet connections have the same bandwidth.

• Open protocols provide a way to standardize data transmission between different devices.

• Protocols for Internet communication, such as TCP/IP, are intended to define a standard format for messages sent between devices on the Internet.

• Removing Digital Divide: Providing accessibility features may allow some groups to access technology and content that they previously could not access.

• Actions to reduce digital divide:

  • I. Providing free education and training on how to use computing devices

    II. Providing free or low-cost computing devices to low-income individuals

    III. Providing networks and infrastructure to people in remote area

    

• Redundant routing is impossible if there is only one possible path from one device to another. There is only one possible path from P to S (P to R to Q to S).

• The World Wide Web is a system of linked pages, programs, and files that is accessed via a network called the Internet.

• The Internet is designed to scale to support an increasing number of users. ==> DNS help

• The computers can communicate directly because Internet communication uses standard protocols.