Khan Academy APCSP 1/21/2021

The variable isOpen is to be used to indicate whether or not a store is currently open. Which of the following is the most appropriate data type for isOpen ?

Boolean

When I was a kid, our Internet connection had a bandwidth of 56 Kbps (kilobits per second). How many bits per second could that transfer?

56,000 bits per second (bps) 1 kilobit is 1000 bits, so 56 Kbps is 56 x 1000 or 56,000 bits per second.

Which statement is true about computing devices in a computer network?

Each computing device must be able to send data to the other computing devices. A computer network is defined as a group of interconnected computing devices capable of sending or receiving data. The devices must be connected using some mechanism (either wires or wireless technology) that enables them to send data.

Devon navigates to "https://www.orbis.org/en/where-we-work" in his browser and sees this webpage: The webpage includes a logo, map graphics, interactive map pop-ups, and a custom font. Which of these resources are loaded using the Hypertext Transfer Protocol? 👁️Note that there may be multiple answers to this question.

Each graphic file The HTML of the webpage The logo The JavaScript code for the map pop-ups The custom font file

Which of the following activities poses the greatest personal cybersecurity risk?

Reserving a hotel room by e-mailing a credit card number to a hotel

According to the Internet Protocol (IP), messages should be split into packets before being sent over the Internet. One problem with splitting the message into packets is that they might arrive out of order. TCP is a protocol that can deal with out-of-order packets. This diagram shows the structure of a packet when using TCP/IP: https://cdn.kastatic.org/ka-perseus-images/cce4bebe8a62cb211c52f051f7173e8f098cdd1e.svg The IP header and TCP header both contain multiple pieces of metadata. Which part of the packet contains the sequencing information that's used by TCP to reassemble packets?

TCP header The TCP header contains metadata that helps with the reliability aspects of TCP, such as packet reassembly and packet retransmission. Specifically, TCP uses the sequence number in the header to reassemble packets in the correct order.

One problem with packet-based messaging systems like the Internet Protocol is that packets might arrive out of order. TCP is a protocol that can deal with out-of-order packets. When used over IP, each IP packet contains a TCP segment with metadata and data. Which part of the packet contains the sequencing information that's used by TCP to reassemble packets?

TCP metadata The TCP metadata helps with the reliability aspects of TCP, such as packet reassembly and packet retransmission. Specifically, TCP uses the sequence number in the metadata to reassemble packets in the correct order.

Which of these is not a protocol that powers the Internet? another

API An API (Application Programming Interface) specifies how the procedures in a library behave and how they can be used. It is not a protocol.

Feiya has several computing devices around the home that are connected to the Internet: A smart home assistant (connected via wireless) A laptop computer (connected via wireless) A desktop computer (connected via Ethernet) Which of her devices use the Internet Protocol (IP) when sending data through the Internet?

All of the devices Many types of computing devices can be connected to the Internet. All devices that send data over the Internet must use the Internet Protocol to do so.

Which of these statements about the digital divide is true? another

Even for-profit companies can take actions to help bridge the digital divide. Many hardware providers and Internet carriers have put out efforts to bridge the digital divide, such as providing low-cost hardware or Internet access.

The Internet Protocol (IP) includes a rule that each message must include a source IP address and a destination IP address. What are the likely consequences of a computer sending a message that does not follow that IP rule? I. The administrator of the device will receive a message from the Internet Protocol Authority (IPA) reminding them of the proper addressing format. II.The message will arrive at its destination more slowly since it will be forced to travel along slower network connections for violating the rules. III. The message may not arrive at its destination at all.

III only The IP rules exist so that two computers can successfully send messages to each other over the Internet. If a computer fails to follow the addressing rules when sending a message, it is most likely the case that the message will not make it to its final destination.

One problem with packet-based messaging systems like the Internet Protocol is that packets might arrive out of order. TCP is a protocol that can deal with out-of-order packets. When used over IP, each packet contains a TCP segment with metadata and data. Which of the following best describes how TCP can reassemble out-of-order packets?

The TCP metadata includes fields that describe where the packet belongs in the sequence. The TCP metadata helps with the reliability aspects of TCP, such as packet reassembly and packet retransmission. Specifically, TCP uses the sequence number in the metadata to reassemble packets in the correct order.

Which of these best describes the fault tolerance of routing on the Internet?

There are multiple routes for each IP packet to follow. A packet can be re-routed if a path becomes unavailable.

A group of organizers are putting together a conference called DevFest and want to make sure the Internet connection will be reliable. They partner with two Internet providers, Komkastic and SupaSonic. This diagram illustrates their connection to the Internet: https://cdn.kastatic.org/ka-perseus-images/da2e97b7f8a4a091f2c0b082a18d695056eeae56.svg Each circle is a router, each line is a connection, and the lines with arrows indicate connections to further routers on the Internet. Unfortunately, this network is not fault tolerant: there's still a single point of failure. Which router needs to stay available for DevFest to have a working connection to the Internet?

Router D

Why does each IP packet contain a destination address?

Routers use the destination address to decide where to send a packet next.

A school installs four smart sensors that can detect vaping. The sensors are connected to the Internet so that district administrators can visit a password-protected website and view data in real-time. The administrator can also send a command to a sensor to trigger an alarm mode. According to the Internet Protocol (IP), each sensor must have a unique identifier so that it can send and receive data over the Internet. Which table shows identifiers that could be used by IP to identify the sensors? Choose 1 answer:

Sensor/Identifier Sensor 1/241.36.170.245 Sensor 2/80.12.159.104 Sensor 3/46.84.179.85 Sensor 4/203.218.117.190 Those identifiers look like IPv4 addresses. According to IP, an IP address is the way to identify a device that can receive data. An IP address is a unique number, such as 204.182.153.189 (IPv4) or cfd1:530a:4872:d244:a06f:2bca:d96f:b18 (IPv6).

The figure below represents a network of physically linked computers labeled A through G. A line between two computers indicates that the computers can communicate directly with each other. Any information sent between two computers that are not directly connected must go through at least one other computer. For example, information can be sent directly between computers A and B, but information sent between computers A and C must go through other computers. https://assets.learnosity.com/organisations/537/media.academicmerit.com/b2b92b3f6ccb51da5de938f94d7b7480/original.png What is the minimum number of connections that must be broken or removed in the network before computer E can no longer communicate with computer F?

3

NSFNET was a computer network from the 1980s that connected the computer science departments of universities. In 1986, NSFNET connected 6 departments across the US: Redundancy in a network makes it more fault-tolerant. When two computers in a network are connected by multiple routes, that adds redundancy. How many routes are there between San Diego and Illinois?

3 routes

NSFNET was a computer network from the 1980s that connected the computer science departments of universities. In 1986, NSFNET connected 6 departments across the US: https://cdn.kastatic.org/ka-perseus-images/4cc34396624e79254a6dcf49363c136228b644ea.svg Redundancy in a network makes it more fault-tolerant. When two computers in a network are connected by multiple routes, that adds redundancy. How many routes are there between NCAR and JVNC?

3 routes

Makayla used a tool to measure how many bits she could transfer over her classroom's Internet connection. This table shows the bits transferred each second: Second Bits transferred 1 5000 2 4500 3 5500 4 4000 5 4500 According to those measurements, what is the bandwidth of the connection?

5500 bits/s The bandwidth is the maximum amount of data that can be transferred in a fixed amount of time and is typically measured in bits per second. The maximum bit rate in the measurements table is 5500, so that is the bandwidth of this connection.

Kiara used a tool to measure how many bits she could transfer over her office Internet connection. This table shows the kilobits transferred each second: SecondKilobits transferred 1/840 2/720 3/640 4/880 5/720 According to those measurements, what is the bandwidth of the connection?

880 kilobits/s The bandwidth is the maximum amount of data that can be transferred in a fixed amount of time and is typically measured in bits per second. The maximum bit rate in the measurements table is 880, so that is the bandwidth of this connection.

Which of these situations describes the creation of a computer network?

A college campus creates multiple computer labs in different parts of the campus and connects the labs to each other with underground fiber optic cables. Students can save their file on a computer in one lab and still access their files from another lab. A computer network is a group of interconnected computing devices capable of sending or receiving data. This situation describes a network of computers that are able to send and receive files.

In the field of computer networks, what is a protocol?

A documented set of rules that describe the behavior of devices in the computer network

A 2016 report found these statistics for citizens of Bolivia: Urban>Rural Which of these would be the most effective way to reduce the digital divide between the urban and rural households?

A program that donates refurbished laptops to residents of rural villages. This would directly increase the number of households with computers in rural areas.

A teacher is writing a code segment that will use variables to represent a student's name and whether or not the student is currently absent. Which of the following variables are most appropriate for the code segment?

A string variable named studentName and a Boolean variable named isAbsent

Which of these situations describes a computer network?

A video gaming club sets up six powerful computers in a room and connects them with Ethernet cables to a router. The club members play multi-player games together. A computer network is a group of interconnected computing devices capable of sending or receiving data. This situation describes a local area network (LAN), which is a common type of network for groups of computers that want to communicate with each other very quickly.

Bharat runs a computer room at a library. The room has a variety of Internet-connected devices: 20 desktop computers (connected via Ethernet) A 3-d printer (connected via wireless) A security camera (connected via Ethernet) Which of those devices use the Internet Protocol (IP) when sending data through the Internet?

All of them (the desktop computers, 3-d printer, and security camera) Many types of computing devices can be connected to the Internet. All devices that send data over the Internet must use the Internet Protocol to do so.

What is true about the computing devices exchanging data over the Internet?

All the computing devices that are exchanging data over the Internet are following the rules of the Internet Protocol (IP). The IP includes rules for message addressing (necessary for routing data from source to destination) and message formatting (necessary for correct interpretation of the data). Two computing devices can only successfully exchange data if they follow the same rules for addressing and formatting.

Which of the following aspects of the Internet has most increased its scalability?

Any computing device can connect to the Internet as long as it follows the open Internet protocols. Billions of computing devices have been able to connect to the Internet easily, since all they need to do is use software that follows the free openly available protocols. As long as the protocols remain open and there is not a requirement for devices to go through a long formal registration process, billions more devices can keep connecting.

Which of these is an accurate description of how the TCP/IP protocols send data around the internet?

Computers split messages into packets and send them through routers to their final destination. The destination computer acknowledges the receipt of each packet, so that the sending computer can ensure every packet is delivered. When communicating using IP, all messages are split into packets and sent through routers. When using TCP over IP, the recipient sends back an acknowledgment of each received packet, which improves the reliability of transmission.

In 2015, the nation of Burundi had an average bandwidth per Internet connection of 11.24 kb/s. In 2016, their average bandwidth was 6.91 kb/s. Which statement is true based on those statistics?

Internet connections in Burundi in 2015 were able to transfer more bits per second than connections in Burundi in 2016. The bandwidth of a computer network is the amount of data that can be sent in a period of time. Since the bandwidth was higher in 2015 than in 2016, that means that connections could transfer more data per second then

Rafi is developing an application to send urgent information about global health crises over the Internet to hospitals. He is worried about packets getting lost along the way and the effect that will have on the accuracy of the information. What is his best option for dealing with lost packets?

Rafi can use the Transmission Control Protocol for communication, since TCP has ways to recover when packets are lost. TCP is a data transport protocol that works on top of IP and includes mechanisms to handle lost packets, such as retransmission of lost packets.

The Internet Protocol (IP) describes how packets can be sent from a sender to a receiver. First, the sender creates an IP packet with the destination IP address in the packet header. Which of these sequences correctly describe the next steps in routing that packet?

The sender sends the packet to the nearest router. The router looks in a forwarding table to find a router that will get the packet closer to its destination and sends the packet to that router. Each subsequent router uses their forwarding table to pick the next router.

A student is recording a song on her computer. When the recording is finished, she saves a copy on her computer. The student notices that the saved copy is of lower sound quality than the original recording. Which of the following could be a possible explanation for the difference in sound quality?

The song was saved using fewer bits per second than the original song.

The TV show Silicon Valley revolved around a startup and their attempt to bring a new product to market. At one point, the creators of the startup say this about their product: "We're making the world a better place through scalable fault-tolerant distributed databases." What does it mean for the databases to be scalable?

They can continue functioning even if there is a significant increase in the number of operations they must perform. A scalable system is one that remains effective even with very high amounts of usage.

Assume that both lists and strings are indexed starting with index 1. The list wordList has the following contents. ["abc", "def", "ghi", "jkl"] Let myWord be the element at index 3 of wordList. Let myChar be the character at index 2 of myWord. What is the value of myChar ?

"h"

Which of these configurations does NOT represent a computer network of six devices? [The blue rectangles indicate devices and the green lines indicate a communication path between the devices]. (another one)

https://cdn.kastatic.org/ka-perseus-images/2326ec7a8f329b8b781f8ec8961af7971ab1504f.svg A computer network is a group of interconnected devices that can send and receive data from each other. There are two networks of three devices each in this diagram, but the two networks are not connected to each other with any lines. This does not represent a computer network of six devices.

Consider the following statement: The World Wide Web is a web connecting billions of <NOUNS>. What would be the most accurate replacement for <NOUNS>?

webpages The WWW connects together billions of webpages (and their associated resources such as images and videos).

Consider the following code segment. p<-10 q<-20 r<-30 s<-40 p<-q q<-r s<-q r<-p What is the value of r as a result of executing the code segment?

20

Which of these situations describes a computer network? Choose 1 answer: (different question)

A company gives every employee a desktop computer and connects each of the computers to each other using wires, so that they can quickly transfer files and messages. A computer network is a group of interconnected computing devices capable of sending or receiving data. This situation describes a company's internal computer network (often called an intranet), which is common at companies that want to connect their own computers together without exposing them to the dangers of the global Internet.

Which of the following is the best description of an IP address?

A number assigned to a computing device that can receive data on the Internet An IP address is a unique number that identifies an Internet-connected device. When a device wants to send data to another device, it must specify that device's IP number.

Which of the following is the best description of an IP address? another

A number that identifies Internet-connected devices An IP address is a unique number that identifies each Internet-connected device. There are two kinds of IP addresses: IPv4 (e.g. 242.185.95.235) and IPv6 (a longer number typically written in hexadecimal, such as cfd1:530a:4872:d244:a06f:2bca:d96f:b18). When a device wants to send data to another device, it must specify that device's IP number.

The following is an incomplete diagram representing the World Wide Web: https://cdn.kastatic.org/ka-perseus-images/2d302901077e39122b4ec62024fd84bca7a3d089.svg What would be the most accurate icon to replace the question mark? Choose 1 answer:

An icon of a webpage The WWW is a system of linked websites (and associated resources such as audios, videos, and scripts).

A computer program uses 3 bits to represent integers. When the program adds the decimal (base 10) numbers 5 and 3, the result is 0. Which of the following is the best explanation for the result?

An overflow error occurred.

Jolene navigates to "https://www.nationaltrust.org.uk/" in her browser and sees this front page: The website includes a logo, photos, an interactive slideshow, and a custom font. Which of these resources are loaded using the Hypertext Transfer Protocol? 👁️Note that there may be multiple answers to this question.

Each image file The HTML of the webpage The logo The slideshow JavaScript library The custom font file

Fen navigates to "https://www.conservationfund.org/" in her browser and sees this on the front page: The front page includes a logo, photos, a video, an interactive slideshow, and a custom font. Which of these resources are loaded using the Hypertext Transfer Protocol? 👁️Note that there may be multiple answers to this question.

Each photo file The HTML of the webpage The logo file The JavaScript code for the slideshow. The custom font file The video file

Ororo typed this URL in her browser's address bar: https://www.nssl.noaa.gov/ After a few seconds, the browser loaded the webpage: Which of these protocols were used by the browser in fetching and loading the webpage?

HTTP IP TCP The Hypertext Transfer Protocol (HTTP) is used by the browser to tell the host computer what file it wants to retrieve. The Internet Protocol (IP) is used for routing IP packets between Logan's computer and the server, based on IP addresses. The Transmission Control Protocol (TCP) is used for making sure the IP packets all arrive correctly and in order.

Which of these are a requirement for a computer to access the Internet? I. A web browser that can load websites and associated multimedia files II. The ability to connect that computer to another Internet-connected device III. An encryption key used to secure communications between the computer and other Internet-connected computing devices

II only The ability to connect a computer to an Internet-connected device (such as a router) is the only requirement for access to the Internet. The other two options are not requirements.

Which description of Internet communication is accurate?

Internet communications are powered by many protocols. One of the most important protocols is the Internet Protocol (IP) since it describes both addressing and routing. Other protocols add layers of functionality on top of that protocol, such as TCP for reliable transmission.

When a computer loads a webpage, it sends a message to a web server over the Internet. How many Internet protocols are used to send and receive the message?

It always uses multiple protocols. Every message uses a stack of protocols, with each protocol providing a layer of functionality. There are protocols for the physical link layer (such as Ethernet), IP for the networking layer, TCP or UDP for the data transport layer, and many protocols for the application layer (HTTP, DNS, TLS, FTP, SMTP, etc.). For example, an HTTP request may use a stack of HTTP, TCP, IP, and Ethernet.

Amazon describes their web services platform like this: Amazon Web Services (AWS) is a highly reliable, scalable, low-cost infrastructure platform in the cloud that powers hundreds of thousands of enterprise, start-up and public sector business with organizations in over 190 countries around the world. What does it mean for the platform to be scalable?

It continues operating when experiencing traffic surges. A scalable system is one that remains effective even with high numbers of users.

Which of these is a way that the Internet Protocol (IP) contributes to Internet communications? another 2

It describes an addressing scheme to uniquely identify each node on the Internet. The Internet Protocol (IP) describes both an addressing scheme (which assigns IP addresses to Internet-connected devices) and a routing strategy (which routes messages based on destination IP address).

Each IP packet contains a destination address. What is the primary purpose of the destination address?

It helps the router know where to send the packet.

In what situations is the Internet Protocol (IP) used? Choose 1 answer:

It is used every time that two computing devices send data to each other over the Internet. IP is a core protocol in the Internet protocol stack. The Internet Protocol both describes how to identify computing devices by IP address and how to route data from one device to another. IP is used every time that devices on the Internet communicate with each other.

How often is the Internet Protocol (IP) used in Internet communications?

It is used whenever two computing devices communicate with each other over the Internet. IP is a core protocol in the Internet protocol stack. The Internet Protocol both describes how to identify computing devices by IP address and how to route data from one device to another. IP is used every time that devices on the Internet communicate with each other.

When do Internet-connected computing devices use the Internet Protocol (IP)?

It is used whenever two computing devices send data to each other over the Internet. IP is a core protocol in the Internet protocol stack. The Internet Protocol both describes how to identify computing devices by IP address and how to route data from one device to another. IP is used every time that devices on the Internet communicate with each other.

ASCII is a character-encoding scheme that uses 7 bits to represent each character. The decimal (base 10) values 65 through 90 represent the capital letters A through Z, as shown in the table below. What ASCII character is represented by the binary (base 2) number 1001010 ? (J=74)

J

A programmer has a need to round many numeric values to the nearest integer. Which of the following best explains the benefit of using a list as a data abstraction in this situation?

Keeping the numeric values in a list makes it easier to apply the same computation to every data element.

How many protocols are used when a message is sent over the Internet?

Multiple protocols are used when a message is sent over the Internet. The computer uses the stack of protocols that are most fitting for the type of message. Every message uses a stack of protocols, with each protocol providing a layer of functionality. There are protocols for the physical link layer (such as Ethernet), IP for the networking layer, TCP or UDP for the data transport layer, and many protocols for the application layer (HTTP, DNS, TLS, FTP, SMTP, etc.). For example, an HTTP request may use a stack of HTTP, TCP, IP, and Ethernet.

In the Internet Protocol (IP), computers send messages to each other through a network of routers, with each message split up into packets. How do routers determine where a packet needs to go?

Routers look at the IP packet header and use the destination address field.

There are some times of the year where online shoppers make significantly more purchases. One of those times is Cyber Monday, the Monday after the US Thanksgiving holiday. Large shopping websites may prepare in advance to make sure their infrastructure is scalable to handle Cyber Monday shoppers. Assuming a store where approximately 50% of shoppers make a purchase, which of these charts represent an online store that scales well to meet the demand of a surge of shoppers? The purple line shows all the shoppers on the website, while the green dashed line shows the number of sales.

Shoppers is above sales and both are going up at a 45 degree angle but the sales is halfway as high as the shoppers. This chart shows a surge in shoppers plus it shows that the website handles the surge well, since the amount of sales grows in proportion to the amount of shoppers. A scalable website is one that can remain effective even under high usage, like this chart shows.

A new high school is built and needs to be connected to the Internet. The IT administrator found these four local providers for Internet services: (Provider/Bandwidth) BeyondNet/100 Mbps SpectralWeb/50 Mbps FinalLink/1000 Mbps TopSat/25 Mbps Which of these comparisons between the providers is correct?

SpectralWeb can transfer 2 times more data per second than TopSat. The bandwidth of a connection measures the maximum amount of data that can be transferred in a fixed amount of time. SpectralWeb has a bandwidth of 50 Mbps while TopSat has a bandwidth of 25 Mbps, so the SpectralWeb connection can transfer 2 times the amount of data per second.

A company moved into a new office space and needs to sign up with an Internet provider. They found these four local providers for business Internet services: Provider/Bandwidth ComSat/25 Mbps EtherealNet/50 Mbps BroadbandUp/100 Mbps UberRing/12 Mbps How do the ComSat and BroadbandUp connections compare?

The BroadbandUp connection can transfer four times the amount of data per second. The bandwidth of a connection measures the maximum amount of data that can be transferred in a fixed amount of time. BroadbandUp has a bandwidth of 100 Mbps while ComSat has a bandwidth of 25 Mbps, so it can transfer four times the amount of data per second.

Aliana just moved into a new home and needs to choose an Internet provider. She researched local providers and found these four: Provider Bandwidth ConnectPlus 100 Mbps HugeNet 25 Mbps Spectra 150 Mbps SuperSonic 1,000 Mbps How much data can be transferred over ConnectPlus as compared to SuperSonic?

The ConnectPlus connection can transfer 10% the amount of data per second. The bandwidth of a connection measures the maximum amount of data that can be transferred in a fixed amount of time. ConnectPlus has a bandwidth of 100 Mbps while SuperSonic has a bandwidth of 10001 Mbps, so it can transfer 10% the amount of data per second.

How does the Internet Protocol (IP) fit into the Internet technology suite?

The Internet Protocol is a protocol used in all Internet communication, but other protocols are also used. The Internet Protocol describes both addressing and routing, so every message sent over the Internet must follow the rules described in the protocol.

Which of the following is a characteristic of the fault-tolerant nature of routing on the Internet?

The ability to provide data transmission even when some connections have failed.

The following chart displays the average bandwidth per Internet user in four island nations in 2016. Australia>Japan>Phillippines>Indonesia Which statement is true based on this chart?

The average Internet connection in Japan can transfer more bits per second than the average connection in the Philippines. The graph shows that Internet users in Japan have a higher bandwidth than users in the Philippines. The bandwidth of a computer network is the amount of data that can be transferred in a period of time. A user with higher bandwidth can transfer more bits per second than a user with lower bandwidth. Thus, this statement is true.

A computer must adhere to the Internet protocols in order to send data through the Internet. Which of these best describe what it means for a computer to adhere to a protocol?

The computer must send data according to the documented rules of the protocol. A protocol is an agreed-upon set of rules that specify the behavior of a system. The Internet protocols are open, so their rules are documented publicly. Adhering to the protocols means following those documented rules.

The following illustration represents a computer network: https://cdn.kastatic.org/ka-perseus-images/1c6d17f421dd942013c7598aab2c9ef21c7c4786.svg What is indicated by the lines between the computing devices in this illustration?

The computing devices are able to send messages to each other. A computer network is a group of interconnected computing devices capable of sending or receiving data. The lines represent the connections between them that messages travel along.

Consider the following code segment. first<-true second<-false second<-first first<-second What are the values of first and second as a result of executing the code segment?

The value of first is true, and the value of second is true.

In 2015, researcher Teresa Correa studied social media use in a sample of 18 to 29 year olds in Chile. She was interested in this age group as they are often called "digital natives," the youth that grew up around computers and the Internet, and she wanted to understand the differences in digital skills amongst them. Which of the following research findings describe a digital divide? 👁️Note that there are 2 answers to this question.

There was a positive correlation between education levels and digital skills. There was a significant difference between the level of digital skills between the men and women in the sample. This describes a digital divide, a difference between groups of people in their ability to access and utilize digital technology.

The US postal service can serve as an analogy for Internet transport protocols. The postal service offers various services: First class letter: the default service with no extras. Certified mail: sent using the standard route but provides the sender with proof that the letter was delivered. Registered mail: sent using secure mechanisms along the way (e.g. locked cages). Similarly, there are multiple transport protocols that can be used on top of IP, with TCP and UDP being the most popular. Which analogy between the transport protocols and USPS services makes the most sense?

UDP is like the first class letter service and TCP is like the certified mail service. UDP is a lightweight data transport protocol that includes very few error checking mechanisms, similar to the first class letter service. TCP adds mechanisms to improve reliability such as acknowledging the receipt of every packet, which is very similar to certified mail service.

A startup creates a website called SpeakerMeter which is designed for use at conferences. SpeakerMeter enables conference attendees to continuously rate speakers as they are speaking, so that speakers can see how much attendees like the different parts of their talks. Which of these situations would reveal the most about SpeakerMeter's scalability?

Using it for a conference with 10,000 attendees The scalability of a system is its capacity to support higher demand and continue functioning effectively. Using SpeakerMeter at a conference with a large number of attendees would reveal whether it can scale to support that many users.

An Internet service provider (ISP) is considering an update to its servers that would save copies of the Web pages most frequently visited by each user. Which of the following is LEAST likely to occur as a result of the update?

Web sites that are not visited frequently might no longer be accessible to users.

Which of the following statements about IP addresses is true?

When data is sent between devices on the Internet, they identify each other with an IP address. According to the Internet Protocol (IP), a device that wants to send information over the Internet must identify the destination with an IP address.

Which statement is true about packet loss on the Internet?

When two computers are using the Transmission Control Protocol (TCP), the packets that they send to each other can be lost along the way, but they can be recovered via retransmission. TCP is a data transport protocol that works on top of IP and includes mechanisms to improve the reliability, such as retransmission of lost packets.

Consider the following code segment. yourList <--- 20, 40, 60, 80 myList <--- 10, 30, 50, 70 yourList <--- myList What are the contents of yourList after the code segment is executed?

[10, 30, 50, 70]

Which diagram best illustrates the process of routing a single packet from a sender to a receiver on the Internet?

https://cdn.kastatic.org/ka-perseus-images/38b71eb6dfa9268387b23736c37000cdec60b9ad.svg When data is routed between two devices over the Internet, the path starts at the sender, hops from router to router, and ends at the receiver.

Which of these configurations does NOT represent a computer network of six devices? [The blue rectangles indicate devices and the green lines indicate a communication path between the devices].

https://cdn.kastatic.org/ka-perseus-images/5174553dac8a46bc7ef82cca446d0801eccf5575.svg ^link to picture A computer network is a group of interconnected devices that can send and receive data from each other. There are two networks of three devices each in this diagram, but the two networks are not connected to each other with any lines. This does not represent a computer network of six devices.

Which diagram best represents the relationship between the Internet and the World Wide Web?

https://cdn.kastatic.org/ka-perseus-images/bdeb5edc2bf3fc3864353f650338de5f849c041d.svg The World Wide Web is a distributed application that runs over the Internet. It is a massive part of the Internet, but there are other applications that run over the Internet as well.

The list wordList contains a list of 10 string values. Which of the following is a valid index for the list?

4

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.

Over the years, engineers have invented many networking technologies for LANs (local area networks). The chart below visualizes the bandwidth of 4 different LAN technologies. Quadrics QsNetII<Infiniband FDR 4X<Omni-Path<NUMALink 7 The x-axis of the chart represents the bandwidth, but it has no unit. Which unit is the most appropriate unit to describe the bandwidth axis?

Gigabits per second Bandwidth is a measurement of how much data can be transferred in a fixed period of time. "Gigabits per second" conveys how many gigabits are transferred in one second, so it is an appropriate unit for the axis.

Many people worry about what would happen if either the Internet or the World Wide Web went down (if they suffered a complete outage and were unreachable). Which of these predictions is correct?

If the Internet went down, the World Wide Web would also go down, since the WWW relies on the Internet protocols. The WWW runs on top of the Internet. It was invented after the Internet had already been around for a few decades, so it could take advantage of the existing Internet protocols and infrastructure.

Which of these situations describes the invention of a networking protocol?

Leighton proposes a set of rules that describe a way for computers to send data on low-bandwidth connections and lists them in a document. Multiple network administrators agree to the rules and implement them. A networking protocol is an agreed-upon set of rules that describe how computing devices can successfully communicate in the network.

Which of the following is a benefit of using a list as a data abstraction in a program?

Lists often allow their size to be easily updated to hold as many data values as needed.

Which of the following least illustrates inequity caused by the digital divide?

On social media networks like Twitter, many celebrities have more followers than people who are less well known. Celebrities generally have more followers due to their celebrity status, not due to their increased access to digital technology and literacy.

The following table compares two data transport protocols from the suite of protocols powering the Internet. Can it handle.../Protocol /1Protocol 2 ...corrupt packets?/Yes/Yes ...lost packets?/No/Yes... out of order packets?/No/Yes What are the most likely identities of Protocol 1 and Protocol 2?

Protocol 1 = UDP, Protocol 2 = TCP UDP is a lightweight data transport protocol whose only error checking mechanism is using a checksum to detect corrupted data. TCP includes additional error checking mechanisms which can handle when packets are lost or out of order.

Josiah used a tool to measure how many bits he could transfer over his home connection to the Internet. This table shows the bits transferred each second: Second/Bits transferred 1/900 2/800 3/700 4/1100 5/800 According to those measurements, what is the bandwidth of the connection?

1100 bits/s The bandwidth is the maximum amount of data that can be transferred in a fixed amount of time and is typically measured in bits per second. The maximum value in the measurements table is 1100, so that is the measured bandwidth of this connection.

An online store uses 6-bit binary sequences to identify each unique item for sale. The store plans to increase the number of items it sells and is considering using 7-bit binary sequences. Which of the following best describes the result of using 7-bit sequences instead of 6-bit sequences?

2 times as many items can be uniquely identified.

A video-streaming Web site uses 32-bit integers to count the number of times each video has been played. In anticipation of some videos being played more times than can be represented with 32 bits, the Web site is planning to change to 64-bit integers for the counter. Which of the following best describes the result of using 64-bit integers instead of 32-bit integers?

2^32 times as many values can be represented.

Which of the following is the best description of how routing works on the Internet?

A computer stores the destination IP address in the IP packet header and sends the packet to the nearest router. The router looks at the IP address and decides where to send the packet next based on a lookup table. The next router does the same, until the packet finally ends up at its destination.

A gardener sets up a network for a garden using a variety of devices: A smart temperature sensor: It runs a program that checks whether the temperature is above or below the target range for that time of day and then triggers the heating or cooling system when needed. A security camera: It uses a machine learning algorithm to detect non-plant motion and sends video footage to a computer. A desktop computer: It generates a graph of the temperature based on data from the temperature sensor and stores video footage from the camera. A wireless router: It uses networking software to enable the sensor, computer, and camera to send data to each other. Which of the devices in the network are considered computing devices?

All of them (the computer, router, camera, and sensor) A computing device is a physical device that can run a program. All of the devices in the network are described as running programs of some kind, so they are all considered computing devices.

Computer A wants to send data to Computer B using the TCP/IP protocols. https://cdn.kastatic.org/ka-perseus-images/033ec5be42675857856100e055a59069d4356c8b.svg What's the best description of how Computer A sends the data?

Computer A splits the data into packets. It does a three-way handshake with Computer B to establish the connection, then sends each packet to the nearest router. If it detects packet loss, it re-sends the missing packets. TCP uses a three-way handshake to establish a connection. TCP includes several mechanisms to improve the reliability of transmission, such as the ability to re-send packets that were lost.

Hank typed this URL in his browser's address bar: https://www.entsoc.org/sci-pol/VBD-Network After a few seconds, the browser loaded the webpage: Which of these protocols were used by the browser in fetching and loading the webpage? 👁️Note that there may be multiple answers to this question.

HTTP IP TCP The Hypertext Transfer Protocol (HTTP) is used by the browser to tell the host computer what file it wants to retrieve. The Internet Protocol (IP) is used for routing IP packets between Hank's computer and the server, based on IP addresses. The Transmission Control Protocol (TCP) is used for making sure the IP packets all arrive correctly and in order.

Logan typed this URL in his browser's address bar: http://wolverinefoundation.org/ After a few seconds, the browser loaded the webpage: Which of these protocols were used by the browser in fetching and loading the webpage? 👁️Note that there may be multiple answers to this question.

HTTP IP TCP The Hypertext Transfer Protocol (HTTP) is used by the browser to tell the host computer what file it wants to retrieve. The Internet Protocol (IP) is used for routing IP packets between Logan's computer and the server, based on IP addresses. The Transmission Control Protocol (TCP) is used for making sure the IP packets all arrive correctly and in order.

Loke used a tool to track the route taken by an IP packet from their school computer to the IP address of the KhanAcademy.org server. Here are the results: {sry} If Loke runs the tool again, what output would he expect to see?

He might see the same stops or might see a different sequence of stops. Routing on the Internet is dynamic. Each time a router receives a packet, it decides where to send it next based on a forwarding table and network conditions. That means that the next packet may follow a different sequence of stops.

Which statements are true about computing devices? I. All computing devices are able to run computer programs. II. All computing devices are capable of being interconnected to form computer networks. III. All computing devices have ways to store data for later use. Choose 1 answer:

I only A computing device is a physical device that can run a program. It does not necessarily have networking hardware or long-term storage.

Bria used a tool to track the route taken by an IP packet from her laptop to the IP address of the Google.com server. According to the tool, this is the route the packets took: 192.168.0.1 96.120.89.13 68.87.198.89 68.86.143.37 162.151.86.57 96.112.146.26 108.170.237.106 108.170.242.83 172.217.164.110 If she runs the tool again to trace the route of a packet to Google.com, what are the possible outputs? I. The same sequence of stops II. The same number of stops, but different IP addresses. III. A shorter sequence of stops. IV. A longer sequence of stops.

I, II, III, or IV. [all 4]. Routing on the Internet is dynamic. Each time a router receives a packet, it decides where to send it next based on a forwarding table and network conditions. That means that the next packet could follow the same sequence of stops or a different sequence of stops. If it follows a different sequence, it may end up making fewer stops or more stops along the way.

In what situations does a computer use multiple Internet protocols to send a message? I. When it sends an encrypted message II. When it wants an acknowledgement that the destination computer received the message III. When it is loading webpage data

I, II, and III Every message that is sent over the Internet uses a stack of protocols, with each protocol providing a layer of functionality. There are protocols for the physical link layer (such as Ethernet), IP for the networking layer, TCP or UDP for the data transport layer, and many protocols for the application layer (HTTP, DNS, TLS, etc). A message to load a webpage might use a stack of HTTP, TCP, IP, and Ethernet, while an encrypted message might use a stack of TLS, TCP, IP, and Ethernet.

Which of the following kinds of computing devices use the Internet Protocol (IP) when sending data over the Internet? I) A tablet computer II) A desktop computer III) A smartphone

I, II, and III Many types of computing devices can be connected to the Internet. Any device that sends data over the Internet must use the Internet Protocol to do so.

Which of these statements about the Internet Protocol (IP) are true? I. It is the only protocol used in Internet communications. II. It is used every time a computing device sends a message over the Internet. III. It is one of many protocols used on the Internet.

II & III only The Internet Protocol is used every time a computing device sends a message over the Internet, to handle the addressing and routing. Other protocols are also used for aspects such as reliability and security.

The following is a diagram of two computers exchanging information over the Internet. https://cdn.kastatic.org/ka-perseus-images/4e6a3950612627ffbb393d0bd575e9dab80afb19.svg The diagram is incomplete, however, as it is missing identifiers for each computer. According to the Internet Protocol (IP), what would be appropriate identifiers to replace <Identifier A> and <Identifier B> in the diagram?

Identifier/Value <Identifier A>/122.69.249.117 <Identifier B>/234.33.12.64 According to the Internet Protocol (IP), an IP address is the way to identify a device that is communicating over the Internet. There are two kinds of IP addresses: IP v4 (the kind shown here) and IP v6 (a longer number typically written in hexadecimal, such as cfd1:530a:4872:d244:a06f:2bca:d96f:b18)

An intranet is a private network set up for an organization like a company or university. Here's an intranet with six routers labeled A - F: [sry] An intranet is more secure, because computers can communicate without using the publicly accessible Internet, but it is often not as fault-tolerant. Imagine that router B needs to send a message to router D. Which of the following situations will lead to the message failing to arrive? 👁️Note that there are 2 answers to this question.

If the connection between D and E goes down. If these two connections go down: C to E, and F to E.

An intranet is a private network set up for an organization like a company or university. Here's an intranet with five routers labeled A - E: Diagram with 5 routers labeled A through E and six lines connecting them. There are no arrows on any of the lines. Line goes from A to B Line goes from B to C Line goes from C to E Line goes from A to D Line goes from D to B Line goes from D to E An intranet is more secure, because computers can communicate without using the publicly accessible Internet, but it is often not as fault-tolerant. Imagine that router A needs to send a message to router E. What situations will lead to the message failing to arrive? 👁️Note that there are 2 answers to this question.

If these 2 connections go down: D to E, and B to C. If these 2 connections go down: D to E, and C to E.

A student used a tool to track the route taken by an IP packet from a library computer to the IP address of the Code.org server. According to the tool, this is the route the packets took: (sry) If they run the tool again (but still with the destination IP address for Code.org), in what way could the next packet's path be different? 👁️Note that there may be multiple answers to this question.

It could stop at fewer routers along the way. Routing on the Internet is dynamic. Each time a router receives a packet, it decides where to send it next based on a forwarding table and network conditions. That means that the next packet may follow a different sequence of stops and may make fewer stops along the way. It could stop at different routers along the way. Routing on the Internet is dynamic. Each time a router receives a packet, it decides where to send it next based on a forwarding table and network conditions. That means that the next packet may follow a different sequence of stops. It could take a different amount of time to get to each stop. The amount of time between stops is dependent on network conditions which are constantly varying due to congestion and hardware issues. It could stop at more routers along the way. Routing on the Internet is dynamic. Each time a router receives a packet, it decides where to send it next based on a forwarding table and network conditions. That means that the next packet may follow a different sequence of stops and may even make more stops along the way.

Which of these is a way that the Internet Protocol (IP) contributes to Internet communications?

It describes a way to uniquely identify computing devices that are connected to the Internet so that messages can be sent to them. The Internet Protocol (IP) describes both an addressing scheme (which assigns IP addresses to Internet-connected devices) and a routing strategy (which routes messages based on destination IP address).

Which of these is a way that the Internet Protocol (IP) contributes to Internet communications? another

It describes how to route packets of data around the Internet, from router to router, based on a destination address. The Internet Protocol (IP) describes both an addressing scheme (which assigns IP addresses to Internet-connected devices) and a routing strategy (which routes messages based on destination IP address).

A copywriter is writing a help center article for a video conferencing service. This is their draft so far: Bandwidth requirements Recommended bandwidth for meetings: For high quality video: 600 <UNIT> For screen sharing only: 75 <UNIT> For audio call only: 80 <UNIT> What would be the most appropriate unit to replace <UNIT>?

Kilobits per second Bandwidth is a measurement of how much data can be transferred in a fixed period of time. "Kilobits per second" conveys how many kilobits are transferred in one second, so it is an appropriate unit for the article.

A copywriter is writing a help center article for a video conferencing service. This is their draft so far: Bandwidth requirements Recommended bandwidth for meetings: For high quality video: 600 <UNIT> For screen sharing only: 75 <UNIT> For audio call only: 80 <UNIT> What would be the most appropriate unit to replace <UNIT>?

Kilobits per second Bandwidth is a measurement of how much data can be transferred in a fixed period of time. "Kilobits per second" conveys how many kilobits are transferred in one second, so it is an appropriate unit for the article.

The following chart displays the average bandwidth per Internet user in four South American countries in 2016. Peru<Brazil<Uruguay<Chile The following chart displays the average bandwidth per Internet user in four South American countries in 2016.

On average, Internet users in Uruguay are able to send more bits per second than users in Brazil. The graph shows that Internet users in Uruguay have higher bandwidth than users in Brazil. The bandwidth of a computer network is the amount of data that can be sent in a period of time. A user with higher bandwidth can send more bits per second than a user with lower bandwidth. Thus, this statement is true.

Which diagram best illustrates the process of routing a single packet from a sender to a receiver on the Internet?

One green path, blue box to blue box. When data is routed between two devices over the Internet, the path starts at the sender, hops from router to router, and ends at the receiver.

Which of these is not a protocol that powers the Internet?

PII PII (Personally Identifiable Information) is information about a person that can be used to identify them. It is not a protocol.

A 2018 survey of South African households found that only 10.4% of households have Internet access and 21.5% have a computer. Which of these would be the least effective way to reduce the digital divide across households?

Providing free subscriptions to an online video courses about digital literacy Most citizens in South Africa do not yet have access to the Internet, and especially do not have access to high-speed Internet necessary to watch videos. They will not be able to take advantage of the subscription until they have more computers and Internet access.

A new Internet provider ZoomyZoomy is creating advertising that focuses on the bandwidth of their connections. Which of these slogans has the correct unit?

Sign up now for a bandwidth of 50 megabits/second! Bandwidth is a measurement of how much data can be transferred in a fixed period of time. It's typically measured in multiples of bits per second, such as Kbps (kilobits/second), Mbps (megabits/second), and Gbps (gigabits/second).

Which of these tables is accurate about packet loss on the Internet?

Statement/IP/TCP/UDP Packets can be lost. True/True/True Lost packets are retransmitted. False/True/False Whenever packets are sent around the Internet, packets can be lost. None of the protocols in the table can actually prevent packet loss. However, TCP is a protocol that works on top of IP and includes a mechanism to retransmit lost packets.

Every year during the Christmas holiday, Google hosts a website to help track the path of Santa around the globe. The website goes from zero traffic to millions of visitors in a small period of time. Before the website goes live, site reliability engineers (SREs) are in charge of making sure that the Santa tracking website will be able to withstand the spike in traffic. Which of these strategies is the best way to verify that the Santa tracking website is scalable?

The SREs can use Google-owned machines to simulate large amounts of visitors on the website and monitor the website to see how it reacts. A scalable system is one that remains effective even with high numbers of users. Simulating large amount of users is a good way to assess the scalability of a system.

Lavanya is shopping for her first house. At an open house, a real estate agent calls the house a "smart home" and explains that all of the home appliances are also computing devices that are connected together in a computer network. What is the benefit of networking the devices together?

The computing devices can transfer data to each other. Networking multiple computing devices together enables them to transfer data to each other by sending messages back and forth.

Which of these statements about the digital divide is true?

The digital divide is affected by geography; some areas are harder to connect to the Internet than others. High-speed access to the Internet requires fiber cables installed underground or underwater. That makes it harder to bring high-speed Internet to some areas, such as mountainous regions and islands.

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 to the user?

The file is broken into packets for transmission. The packets must be reassembled upon receipt.

This diagram illustrates a wireless network made up of five devices: an Apple iPhone, an Android phone, a desktop computer, a tablet computer, and a wireless router. https://cdn.kastatic.org/ka-perseus-images/13f4f688f39929ac2e6d1455c84adeb77e79872e.svg Why are those devices considered computing devices?

They are capable of running computer programs. A computing device is a physical device that can run a program.

Consider the following code segment. firstList ←← ["guitar", "drums", "bass"] secondList ←← ["flute", "violin"] thirdList ←← [] thirdList ←← firstList firstList ←← secondList secondList ←← thirdList What are the contents of secondList after the code segment is executed?

["guitar", "drums", "bass"]

Which of these configurations does NOT represent a computer network of six devices? The blue rectangles indicate devices and the green lines indicate a communication path between the devices. Choose 1 answer:

https://cdn.kastatic.org/ka-perseus-images/d7bde537105c186ffc5f1749c551986f5ca3413e.svg A computer network is a group of interconnected devices that can send and receive data from each other. There are two networks of three devices each in this diagram, but the two networks are not connected to each other with any lines. This does not represent a computer network of six devices.

The variable age is to be used to represent a person's age, in years. Which of the following is the most appropriate data type for age ?

number

The following passage describes the Internet but contains a missing adjective: The Internet is powered by <???> protocols. As a consequence, any computing device can join the Internet as long as they have the ability to connect to another Internet-connected device. There is no need to pay a fee to implement the protocols or to learn how they work. What is the most appropriate adjective to replace <???>?

open An "open" protocol is nonproprietary. That means that the protocols are fully described in publicly available documents, and that you do not need to pay a fee to read or implement the protocol.

Consider the following code segment. x ← 25 y ← 50 z ← 75 x ← y y ← z z ← x Which of the variables have the value 50 after executing the code segment?

x and z only