Unit 2

Who invented the internet?

Vint Cerf and Bob Kahn

What was the internet originally called?

Advanced

Research

Projects

Agency

Network

Why was the internet created?

1). A way for government researchers to share information with each other on separate computers

2). A decentralized way of communicating even after a nuclear attack happened

Does the internet’s network branch off from a center point of origin? Why or why not?

No, because the purpose was to be decentralized so if one part was cut off then the system still worked

What kind of information does the internet send and receive?

Binary

Define bandwidth

Maximum transmission capacity of a device

Bandwidth is a measure by *blank*

Bitrate

Bandwidth determines what?

Determines the maximum amount of data that you can send and receive at once

Define Bitrate

Number of bits that we can send over a given period of time. Measured in bits per second

Define Latency

Times it takes for a bit to travel from one place to another

Easy connection to bandwidth, bitrate, latency

Bandwidth: number of lanes on the highway

Bitrate: Number of cars on the highway

Latency: Actual time it takes the cars to go from one exit to another

Define what an ISP is

Internet service provider. Ex: COX, warner cable

Define what a protocol is:

A well-known set of rules and standards used to communicate between machines

Why are protocols necessary for communication between devices ESPECIALLY when connecting to each other on the internet?

If they agree on the same rules, this will allow the machines to communicate without any hiccups and the same way every time

One of the most important protocols used on the internet is called the

internet protocol

What does the internet protocol do?

1). Attach the sending device’s IP address to each packet

2). Attach the receiving device’s IP address to each packet

What is the DNS protocol?

Domain Name System matches domain names (like ww.code.org) to their corresponding IP addresses (174.129.14.120)

How are DNS servers separated into?

hierarchy, which means these servers are split into specific major zones such as .com, .edu, .gov

How does the DNS work starting with the *invisible* dot?

1). Looks in the operating system’s memory to see if the IP address is there

2). Resolving Name Server starts at the root, then looks in the corresponding top-level server, then looks into the subdomain servers if necessary and stores this information in its cache for later use

What is cache? How does it help our computer when on the internet?

Cache-Browser’s memory; this helps our computer remember IP addresses of domain names we’ve already found before

Explain the major downfall and dangers of the DNS being open and public

A cybercriminal can change the corresponding IP address of a domain name to another and unsecure IP address which is called DNS spoofing.

This is a valid IPv4 or IPv6 (True or false)

92\.169.42.163

The pattern is 2-3-2-3

How does the information travel through the internet?

Electricity, light, radio waves

Give an example of electricity being used as a method with pros and cons

Ethernet cables

pros: Cheap Hardware

Cons: Signal loss over a few hundred feet

Give an example of light being used as a method with pros and cons

Fiber Optic Cables

Pros: Really fast, no signal loss

Cons: Really expensive, hard to work with

Give an example of Radio Waves being used as a method with pros and cons

Wireless Routers

Pros: Wireless (mobile)

Cons: Short Range

Explain why the internet is not truly wire-less

Even if you are using your device using ‘wireless’ Internet, is still is being sent to a wireless router that is connected through an Ethernet cable which is connected to an ISP’s server and set throughout the world using fiber optic cables.

What is a packet?

A small piece of data that makes up a larger piece of data that is being sent through the internet

What are two things always labeled on a packet?

1). IP address of where it came from

2). IP address of where it is going

Define the job of a router

Essentially Internet “traffic managers” to keep the packets moving smoothly even if some router have been damaged using dynamic routing

Can a computer or packets themselves choose the path that they take to reach their destination?

No, the packets nor the sending computer is in control of which path each packet will take; this is the job of the routers that it encounters

True or False:

The information that you send to and from the internet to other connected devices must used a fixed path each and every time

FALSE

How does the internet rely on redundancy?

Packets can be sent on so many different paths/routes by routers

What does fault tolerant mean?

Network can keep sending packets even if something goes wrong

What does (TCP) do?

Manages the sending and receiving of all your data as packets

What are the two jobs of the TCP?

1). When sending: Puts a sequence number on the packets to tell the receiving computer on how to put the data back together.

2). When receiving: Tries to put the received data back in order using the given sequence and requests new packts if a packet is missing.

What does the user datagram protocol (UDP) do?

Rapid fires packets from the sending computer to the receiving computer

What is scalability?

It is important for the internet to be scalable because this help you not have to completely start over and build a new software system. 

What does redundant mean?

It is important for the internet to be redundant because it provides more reliability. It help minimize the number of shutdowns and helps maintain a consent flow of stream. 

What are the servers called that hold directories of a webpages?

Web Servers

We click on *blank* to travel from one webpage to another

Hyperlinks

The text that contains these links are called *blank*

hypertext

Define the Hypertext Transfer Protocol (HTTP)

The language used to communicate between browsers and servers

What are the two types of requests you send to the web server?

“Get” request- Used to get data from a specified webpage like a login page

“post” request- Sends data to a specified webpage like uploading an image to an application like instagram

Define what HTML is

This is a language that is used to markup websites for graphical purposes and to show the location of other hyperlinks on that webpage

Why do webpages with pictures load slower?

Each picture is sending its own request for the HTML

What is the job of a cookie?

To remember small pieces of information that you enter into websites like your username and/ or password

What is the job of a web browser?

The application on a computer that lets the computer communicate with the web servers

When and who invented the first web browser and ultimately invented the WWW

1991, Timothy Berners-Lee

What are the layers of the internet?

Application layer, transport layer, internet layer, link/physical layer

What is inside the application layer?

HTTP/DNS, WWW

What is inside the transport layer?

TCP/UDP, packets

What is inside the internet layer?

IP, IP address

What is inside the Link/ physical layer?

Radio, waves, ethernet wires, fiber optic cables

True or false: Each layer is only concerned with itself and its specific job

Ture. One that particular layer has done its job, it then hands if off to the next “layer”. Each protocol does not need to know hw the other layers work because it just trusts that the other layers are working.

name the 3 main types of networks

Local Area Network, Wide Area Network, Data Center Network.

Which is the most common computer network?

(LAN) Local Area Network

What network covers a large geographical area and it is made of LANS

Wide Area Network (WAN)

Which network is used with data centers where data must be exchanged with very little delay?

Data center network

What is the relationship between the internet and the world wide web?

The world wide web is built on top of the internet

how are webpages conencted?

Webpages are connected by search engines using web crawlers (also known as spiderbots) and by our government (like the library of congress) for historical research purposes.

What are the pros of data persistence?

Digital data is to losing qualities between copies of data (generational loss)

Websites tends to have backups of all its users’ data. This means deleted info can be retrieved.

What are the cons of data persistence?

It is almost IMPOSSIBLE to *permanently* delete something

List the 3 internet dilemmas

Digital Divide, Net Neutrality, Internet Censorship

Define digital divide

The restriction of access to the Internet and information and communication technologies because of geographic areas, age, and different socio-economic levels

Define Net Neutrality

The idea that ISPs should be able to enable access to all content and application regardless of the source, and without favoring or blocking particular products or websites

Define Internet Censorship

The control or suppression of what can be accessed, published, or viewed on the Internet enacted by regulators or the government.

Define digital literacy

\
An individual ability to find, evaluate, and compose clear information through writing and other media on various digital platforms.

the layer of the internet

link layer, network layer, transport layer, application layer

What is the FTP

file tansfer protocol