KHAN ACADEMY THE INTERNET STUDY LIST QUESTIONS AND ANSWERS WITH COMPLETE SOLUTION

KHAN ACADEMY THE INTERNET STUDY LIST QUESTIONS AND ANSWERS WITH COMPLETE SOLUTION Tiffany is helping a family member learn how to use Gmail. She notices the website is using a different font and logo, and that the emails are suspiciously worded: Tiffany suspects that has been compromised by a DNS spoofing attack. Which of these are good next steps? ️Note that there are 2 answers to this question. Ans- Contact the Gmail team via social media or phone Close the Gmail tab TCP/IP are the protocols that route data around the internet. What are they each responsible for? ️Note that there are 2 answers to this question. Ans- IP is responsible for routing of packets from source to destination across the internet. TCP is responsible for reliable transmission of packets. IP v4 addresses currently cost more to lease than in the past. What's the most likely explanation for why people are willing to pay more for IP v4 addresses now? Ans- There are very few available IP v4 addresses in the world, and the scarcity increases the demand. Over the years, engineers have invented many networking technologies for LANs (local area networks). Many are still in use, and many of the very slow ones were abandoned long ago. The following is a sampling of LAN technologies and their bandwidths. Sort the technologies from lowest to highest bandwidth, with the lowest on the top and the highest on the bottom: "LocalTalk" @ 230 kbit/s "Econet" @ 800 kbit/s "Omninet" @ 1 Mbit/s "FireWire" @ 400 Mbit/s "Gigabit Ethernet" @ 1 Gbit/s "Omni-Path" @ 100 Gbit/s Ans- "LocalTalk" @ 230 kbit/s "Econet" @ 800 kbit/s "Omninet" @ 1 Mbit/s "FireWire" @ 400 Mbit/s "Gigabit Ethernet" @ 1 Gbit/s "Omni-Path" @ 100 Gbit/s Startuppr is a web company that's running their servers out of their garage. Uptime is important to them, so they pay for two internet service providers, Xfinity & Wave. The ISP routers then send their server's packets to the rest of the internet. Unfortunately, this network is not fault tolerant: there's still a single point of failure. Which router needs to stay available for Startuppr servers to stay connected to the internet? Ans- Router A NSFNET was an early internet connecting 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. In this network, how many routes are between San Diego and Cornell? Ans- 4 routes D'Andre is riding a train with wireless internet service. When he logs online, he sees a warning that the wireless network has limited bandwidth. Which online activities are most likely to be affected by limited bandwidth? ️Note that there are 2 answers to this question. Ans- Watching online movies Downloading a large application Which of these could be a valid IP v4 or IP v6 address? ️Note that there may be multiple answers to this question. Ans- 192.168.17.43 2001:0db8:85a3:03eF:7cb3:8a2e:0370:7334 Which of these is the best description of the domain name system (DNS)? Ans- The domain name system associates domain names with IP addresses, like "" with 208.65.153.251. Each IP packet contains a sequence number. What is the primary purpose of the sequence number? Ans- It helps the receiving computer reassemble the packets. Comcast, an Internet Service Provider in the US, has many IP addresses that it can assign to its customer's computers. One IP address is 24.128.139.211. Which explanation best describes the hierarchical nature of that address? Ans- The first part of the address (24.128) identifies the network (Comcast) and the second part (139.211) identifies the individual customer. Nadia is at an internet cafe in Paraguay, where the download speed is 600 kbps. She's chatting with her friend Jun in Singapore, where the download speed is 60 Mbps. How much faster is Jun's speed than Nadia's? Ans- 100x Consider the website: That website hosts the help center for DonorsChoose, a site where teachers can fundraise for classrooms. Which of these statements are true? ️Note that there are 2 answers to this question. Ans- help is a subdomain of org is a top-level domain Why does each IP packet contain a destination address? Ans- Routers use the destination address to decide where to send a packet Over the years, engineers have invented many networking technologies for WANs (wide area networks), connecting large geographic regions like cities and states. The slower technologies are mostly obsolete, but may still be used in developing nations. The following is a sampling of WAN technologies and their bandwidths. Sort the technologies from lowest to highest bandwidth, with the lowest on the top and the highest on the bottom: Ans- "56k line" @ 56 kbit/s "DS0" @ 64 kbit/s "T1" @ 1.544 Mbit/s "VDSL" @ 100 Mbit/s "10 Gigabit Ethernet" @ 9.953 Gbit/s "OC-256" @ 13.271 Gbit/s When packets are routed on the internet, the route for a particular packet is not pre-determined. Instead, the next hop is decided by each router along the way. How does that increase the fault tolerance of routing? Ans- Each router can pick a connection that's currently working and available. Taylor switched WiFi networks from an AT&T network to a Verizon network. He noticed his IP address changed. What's the best explanation for the change? Ans- Verizon has a different set of IP addresses to allocate than AT&T, so Verizon had to give Taylor's computer a different IP address than the AT&T address. Which of these is an accurate description of how the TCP/IP protocols send data around the internet? Ans- 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. A new internet provider ZoomyZoomy is creating advertising for their fast upload speed. Which of these has the correct unit? Ans- Sign up now for an upload speed of 50 Mbps Which are the primary aspects of the domain name system (DNS) that help it scale? ️Note that there are 2 answers to this question. Ans- Scalability in the DNS is helped by caching of domain ↔ IP mappings on multiple machines. Scalability in the DNS is helped by the division of labor between root name servers, TLD name servers, and host name servers. DevFest is a conference that wants to make sure it has a reliable connection to the internet. The conference partners with two internet providers, Comcast and Sonic, just in case one of them goes down. The ISP routers then connect to the rest of 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? Ans- Router A What is the main advantage of the IP v6 addressing protocol? Ans- IP v6 allows for more addresses than IP v4. An intranet is a private network set up for an organization like a company or university. Here's an intranet with 5 routers labeled A-E: An intranet is more secure, because computers can communicate without using the public 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 may be multiple answers to this question. Ans- 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. Jay is playing BigBalloon, an online multiplayer balloon popping game, and is trying to help his team win during a rumble with another team. However, his attempts to pop balloons aren't working. He's clicking the balloons as soon as he sees them, but the other team's clicks are counting instead. What's the most likely explanation for why that might be happening? Ans- Jay's on an internet connection with too high latency. TCP/IP are the protocols that route data around the internet. What are they responsible for? Ans- TCP is responsible for reliable transmission of packets. IP is responsible for routing of packets from source to destination across the internet. The most recent big DNS cache poisoning attacks have been on the cryptocurrency websites MyEtherWallet and Trezor. Those websites help users keep track of their cryptocurrency investments, and they store user credentials that are used for buying and selling. Why would cyber criminals want to DNS spoof a cryptocurrency website? Ans- They can direct those websites to fake websites that ask users for secure information that they can then use on the real website. NSFNET was an early internet connecting 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. Assuming any connection can go down, how many routes are there between NCAR and JVNC? Ans- 3 routes Consider the website: That URL leads to the blog of a gardening tips & tricks website. Which of these statements are true? ️Note that there are 2 answers to this question. Ans- blog is a subdomain of blog is a third-level domain Rosa is trying to explain to a classmate that IP addresses are hierarchical. Which of these explanations are the best? Ans- The first part of an IP address specifies the network, the next part specifies the individual node in the network. Each IP packet contains a destination address. What is the primary purpose of the destination address? Ans- It helps the router know where to send the packet. Noemi works out of an office in San Francisco that recently got an upgrade to a 1 Gigabit Fiber internet connection. Ammar works at a company in Pakistan with a 500 Kbps internet connection. How much faster is the SF office connection than the Pakistan office connection? Ans- 2000x Which of these best describes the fault tolerance of routing on the internet? Ans- There are multiple routes for each IP packet to follow. A packet can be re-routed if a path becomes unavailable. Imagine an internet without the domain name system (DNS). What would that internet be like? Ans- Without the domain name system, we would not be able to use nice URLs like "" to visit websites on the internet. Why does each IP packet contain a sequence number? Ans- Computers use the sequence number to determine the original order of the packets. Emily is trying to use her home computer as a server. She told the IP address to her friend Kolby, and he was able to send messages from his computer to hers. Emily's home just had a power outage, and after a few minutes, the power came back and the internet started working again. However, Kolby can't send messages to Emily's server anymore. Which explanation is the most likely? Ans- Emily's ISP assigned a different IP address to her computer after the power came back on. Computer A wants to send data to Computer B using the TCP/IP protocols. What's the best description of how Computer A sends the data? Ans- 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. Jelani is a student in a Somalia school, where their internet download speed is 400 kbps. He visits relatives in Oakland, California, and stays at a home where the download speed is 60 Mbps. How much faster is the Oakland home's download speed than the Somalian school's download speed? Ans- 150x