Exam "Networks and The Internet"- past Video Q's

What are the 3 Methods to send information form 1 computer to another

Electricity, Light, Radio

HTTP stands for

HyperText Transfer Protocol

Who decides all of the protocols (IETF)

IETF = Internet Engineering Task Force. An open community of engineers, designers, vendors and researchers concerned with the evolution and smooth functioning of the internet.

Question: 1 Which of the following are true about Internet routing? I - For any two points on the Internet, there exists only one path between the two points II - Routing on the Internet is fault tolerant and redundant

II only

A city government is attempting to reduce the digital divide between groups with differing access to computing and the Internet. Which of the following actions is LEAST likely to be effective in this purpose? I. Holding basic computer classes at community centers II. Providing free wireless Internet connections at locations in low-income neighborhoods III. Putting helpful tips for operating computers on the city government website IV. Requiring that every school and library have assistive devices that allow people with disabilities to access computer resources

III.

Redundancy

Improves Reliability (makes the system fault tolerant)

IP Address is Hierarchical. Has 4 sets of numbers. Example:

.93.184.216.34 1. Network .93 2. Sub-Network .184 3. Sub, Sub-Network .216 4. Location of that device .34

Viewing a web page (11 steps) (Step 1)

1) The URL (Uniform Resource Locator) You are locating a resource that exists somewhere on the internet. Where does it exist? Defined by the Domain. Domain where on the internet you need to look for this resource. www.example.com/homepage.HTML After the Domain We have the Path. What resources you are requesting.

Viewing a web page (11 steps) (Step 10)

10) The Original Response is Pierced Together from the Packets. Your computer is able to reconstruct the original message because both the computer and the server are using the same Protocols!

Viewing a web page (11 steps) (Step 11)

11) The Page is Rendered! All this Happens in LESS than a Second!!

Networks

2 or more computers that are connected

Viewing a web page (11 steps) (Step 2)

2) Create an HTTP Request Asking to get to the Homepage with a certain content - Type Content - Language.

What is the bitrate of a system? 1. The number of bits used to encode a single letter 2. The amount of data (in bits) that can be sent in a fixed amount of time 3. The strength of the network connection 4. The distance that data needs to travel in a network

2.

Viewing a web page (11 steps) (Step 3)

3) Use DNS to get the IP Address We don't know the IP address so we go to DNS DNS to get IP address (Remember from before) We get IP addresses. Example: Hey root where is.com etc.

What is the Internet Protocol (IP)? 1. A set of rules describing what behavior is acceptable on the Internet 2. A law that says that the Internet is for everyone 3. A protocol that defines the structure of an Internet address and assigns a unique address to every device on the Internet 4. An agreement that sets a limit on the number of computers than can be on the Internet at any given time

3.

What is the latency of a system? 1. The amount of data (in bits) that can be transmitted at any given time 2. The distance that data needs to travel in a network 3. The time it takes for a bit to travel from sender to receiver 4. The strength of the network connection

3.

Viewing a web page (11 steps) (Step 4)

4) TCP/IP Breaks the Request into Packets TCP/IP breaks the request into several packets and labels them with the proper Metadata.

What information is contained in a packet? 1. The entirety of a digital message 2. The entirety of a digital message, and metadata about the message, including where it came from and where it is going. 3. A small part of a digital message. 4. A small part of a digital message, and metadata about the message, including where it came from and where it is going

4.

What is the function of the Domain Name System (DNS)? 1. To sell website names to web developers 2. To assign a unique domain name to every computer 3. To make sure that each IP address has only one corresponding domain name 4. To translate domain names into IP addresses

4.

How is the bandwidth of a network measured? 1. Bitrate. Higher bitrate means higher bandwidth. 2. Voltage. Higher voltage means higher bandwidth. 3. Frequency of waves. Higher frequency means higher bandwidth. 4. Light. More light means higher bandwidth.

4. Bitrate

Viewing a web page (11 steps) (Step 5)

5) Packets are Routed to the Proper IP Address TCP checks that every packet made it. If not, the server will request that the missing packets are resent.

Viewing a web page (11 steps) (Step 6)

6) The Original Request is Pieced Together from the Packets.

Viewing a web page (11 steps) (Step 7)

7) The Server Creates an HTTP Response This HTTP response includes a status code (200 OK) The actual HTML file is in the response.

4 Sets of numbers. X 8 bits = 32 bits.

8 bits (1 byte per number) 2^8 = 256 possible numbers 0 to 255 2^32 = over 4 billion possible IP addresses.

Viewing a web page (11 steps) (Step 8)

8) TCP Breaks up the Response into Packets

Viewing a web page (11 steps) (Step 9)

9) The Response Packets are Routed back to the Computer TCP checks that all packets made it. If not, the computer will request that the missing packets get resent.

Internet Protocol (IP):

A protocol that defines the layout of an IP address. Internet address.

According to the Domain Name System (DNS), which of the following is a subdomain of the domain example.com? A. about.example.com B. example.com/home C. example.com.org D. example.org

A.

Which of the following best explains what happens when a new device is connected to the Internet?

An Internet Protocol (IP) address is assigned to the device.

Sending Information

Core functionality of the Internet (Binary System 0's and 1's)

What does DNS: Domain Name System do?

DNS transfers names to the IP addresses. Websites register to a DOMAIN. Once they have this DOMAIN name Like: Google.com 172.217.18.714 and CodeHS.com 93.184.216.34 DNS Maps these DOMAINS to IP addresses. DNS Requesting a Web Source from Name to IP. DNS turns the name into Iterm-26P Addresses.

DNS is Scalable

Each layer is only in charge of a small amount of information. Easy to add a single element to a layer.

IP Addresses are Scalable so it is

Easy to add more networks and more devices.

Internet Address

Every device on the internet has a unique internet address. Data sent has a to address as well as a from address. Follows a standard, agreed upon format.

Is the following statement true, or false: Everyone in the world has internet access.

False

Sending Ethernet Cables

Pros: Cheap, Cons: Only covers medium distances, and Send the wire to have a high voltage to represent a 1 and a low voltage to represent a 0.

HTTP does what?

HTTP is a protocol that standardizes the language for talking to web servers to send and receive web sources. HTTP HTML (HyperText Markup Language) HTTP defines how computers request and receive Hyper Text information.

Which of the following statements are true about the Internet? I - The Internet connects devices and networks all over the world II - The Internet helps people collaborate to solve problems III - The Internet helps people communicate IV - There are no negative consequences of the Internet, it is purely positive

I, II, and III

An IPv4 address has 32 bits, so there are 232 (over 4 billion) possible IPv4 addresses. Since the Internet is gaining devices quickly, we will soon surpass 232 unique devices on the Internet. In anticipation of all the new Internet devices, we are in the process of switching to IPv6, which uses 128 bits for a single address. That's 96 extra bits to represent one address! Which of the following statements correctly describes how many more addresses will be possible to represent by switching from IPv4 to IPv6? I. 96 more addresses can be represented with IPv6 II. 296 more addresses can be represented with IPv6 III. 96 times as many addresses can be represented with IPv6 IV. 296 times as many addresses can be represented with IPv6

IV.

Sending Bits with Light

Pros: Travel long distances, Cons: Expensive, and Send the light across so if a bright light it is a 1 and a dim light it is a 0.

Bitrate

Low = 1 bits per second High = 5 megabits per second

DNS is Hierarchical in nature

Root (Server)--> Top Level Domain (.com, .gov, .edu, .org, .me, .de)--> Second Level Domain (codehs, google, stanford, wikipedia, codehs) --> Subdomain (codehs: www hoc, google: www support, codhs: karel, calving

Theory of the Internet summary

SUMMARY a. The internet is a packet switched system through which digital data is sent by breaking down the data into blocks of bits called packets. b. Packets contain both the data being transmitted and control information (METADATA) that helps route the data. c. It is only able to work because all machines have agreed to use the same protocols for creating and reading packets.

Router

Simple Networks (1 Room/1 Building)

How does DNS work?

Step 1) DNS assigns an IP Address by checking memory/cache Step 2) Asks for a Root Server (TLD-Top Level Domain) Step 3) Ask TLD Server: DNS is Hierarchical in nature. Top / Down, SLD-Second Level Domain Setp 4) Ask a Hosting Server www. this IP address Step 5) Save in the CACHE (Memory) for later se we don't have to go through this all over again Step 6) Send the request by sending them your homepage.

Bandwidth

The capacity of data transfer in a system. Measured by bitrate. Speed of data transfer

Latency

The time it takes for a bit to get from the sender to the receiver Low latency: fast connection Fiber optic cable has the best latency (speed of light) 5 microseconds/kilometer Ethernet 300 microseconds/kilometer

What is the purpose of the Digital Millennium Copyright Act?

To criminalize the act of circumventing, or getting around, access controls that block access to copyrighted works.

What is TCP?

Transmission Control Protocol where it allows for multiple packets to be sent between computers, and checks that all packets arrive and are put together in the proper order. TCP also adds a packet number to each pack so that we can track the order of the packets. The numbers allows them to be pieced back together even if they arrive out of order. TCP will re-request the missing packet if it doesn't arrive. TCP/IP defines metadata about the information being sent. (to address, from address, message size, and order number)

What does URL stand for?

Uniform Resource Locator

Sending Bits with Radio Waves

WiFi Router - Cell Tower, Pros: Wireless, Cons: Short Distance

A user enters a Web address in a browser, and a request for a file is sent to a Web server. Which of the following best describes how the file is sent back to the user? a. The file is broken into packets and sent over a network. The packets must be reassembled by the user's computer when they are received. If any packets are missing, the browser re-requests the missing packets. b. The file is broken into packets and sent over a network. The user's browser must request each packet, in order, until all packets are received. c. The server attempts to connect directly to the user's computer. If the connection is successful, the entire file is sent at once. If the connection is unsuccessful, an error message is sent to the user. d. The server repeatedly attempts to connect directly to the user's computer until a connection is made. Once the connection is made, the entire file is sent.

a.

Which of the following is a benefit of the fault-tolerant nature of Internet routing? a. The ability to use a hierarchical naming system to avoid naming conflicts b. The ability to provide data transmission even when some connections between routers have failed c. The ability to resolve errors in domain name system (DNS) lookups d. The ability to use multiple protocols such as hypertext transfer protocol (HTTP), Internet protocol (IP), and simple mail transfer protocol (SMTP) to transfer data.

b.

Two computers are built by different manufacturers. One is running a Web server and the other is running a Web browser. Which of the following best describes whether these two computers can communicate with each other across the Internet? a. The computers cannot communicate, because different manufacturers use different communication protocols. b. The computers can communicate, but additional hardware is needed to convert data packets from one computer's protocol to the other computer's protocol. c. The computers can communicate directly only if the messages consist of text. Other formats cannot be interpreted across computers. d. The computers can communicate directly because Internet communication uses standard protocols that are used by all computers on the Internet.

d.

Addressing

def: Similar to a post office Particular format so they can be read

What way do we read the Hierarchy for DNS to understand it correctly

from the right to the left (We start the Hierarchy from bottom to top so we understand, however the computer reads it the other way)

Because the 32 bit version of the protocol, IP v4 has been around since the 1980's doesn't have enough bytes for all the new devices there is a new one introducing:

introducing the IP v6: So we are transitioning to this now on IP addresses. Each device has an address made up of 128 bits. 2^128 possible addresses Made up of 8, 4 digit hexadecimal Each hex value in 4 bits values 8*4*4=128 bits. Same Hierarchical structure, just more possible combinations.

Information is broken down into ________ and the TCP puts them ______________. All packets must have 1) ________ 2)________ 3) _______. If one packet fails to be received the computer asks for it again until it is received and then the homepage or information is then recieved and put together by the TCP.

packets; back together in the correct order; 1)A destination IP Address 2)A from IP Address 3)The actual data being sent