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Course 2 – The Bits and Bytes Of Computer Networking

Week 6: Troubleshooting and The Future Of Networking

Coursera Study Guide

TABLE OF CONTENT

Congratulations, you’ve made it to the final week in the course! In the last week of this course, we’ll explore the future of computer networking. We’ll also cover the practical aspects of troubleshooting a network using popular operating systems. By the end of this module, you’ll be able to detect and fix a lot of common network connectivity problems using tools available in Microsoft Windows, MacOS, and Linux operating systems.

Learning Objectives

  • Inspect common network connectivity problems.
  • Use tools available in Microsoft Windows, MacOS, and Linux to troubleshoot network issues.

PRACTICE QUIZ: VERIFYING CONNECTIVITY

1. The protocol used to communicate network errors is known as __________.

  • TCP
  • ICMP (CORRECT)
  • UDP
  • Traceroute

Correct! ICMP is used to communicate errors back to the client.

2. The ping utility sends what message type?

  • Echo Request (CORRECT)
  • Destination Network Unreachable
  • Destination Network Unknown
  • Echo Reply

Right on! By default, the ping utility sends an Echo Request ICMP message type.

3. On Windows, one of the tools you can use to verify connectivity to a specific port is ________.

  • Test-NetConnection (CORRECT)
  • tracert
  • nc (netcat)
  • ping

You got it! Test-NetConnection lets you test many things, including connectivity to a specific port on a remote host.

PRACTICE QUIZ: DIGGING INTO DNS

1. One of Level 3’s public DNS servers is ____________.

  • 4.2.2.3 (CORRECT)
  • 8.8.8.8
  • 127.0.0.1
  • 192.168.1.1

Great job! Level 3’s public DNS servers are 4.2.2.1 through 4.2.2.6

2. A DNS resolver tool available on all major desktop operating systems is __________.

  • nslookup (CORRECT)
  • ping
  • host
  • tracert

Awesome! nslookup is available by default on Windows, macOS, and Linux.

3. The organization responsible for DNS at a global level is ________.

  • Google
  • RFC
  • ICANN (CORRECT)
  • IANA

Nice work! ICANN is responsible for DNS at a global level.

PRACTICE QUIZ: THE CLOUD

1. A piece of software that runs and manages virtual machines is known as a __________.

  • cloud storage device
  • cloud computing device
  • hypervisor (CORRECT)
  • virtual instance

Correct! A hypervisor manages many virtual instances running on a single host.

2. Office 365 Outlook is an example of _______.

  • IaaS
  • FttH
  • PaaS
  • SaaS (CORRECT)

You nailed it! Office 365 Outlook is an example of Software as a Service (SaaS).

3. A hybrid cloud is ________________.

  • a combination of a public cloud and a private cloud (CORRECT)
  • a combination of a public cloud and hardware virtualization
  • a combination of a private cloud and a mesh network
  • a combination of virtual hosts and virtual guests

Wohoo! A hybrid cloud runs some services on a cloud provider and some services in-house.

PRACTICE QUIZ: IPV6

1. An IPv6 address is how many bits long?

  • 16
  • 32
  • 64
  • 128 (CORRECT)

Great job! An IPv6 address is 128 bits long

2. The very first field in an IPv6 header is the _______.

  • version field (CORRECT)
  • data payload field
  • source address field
  • traffic class field

Nice work! This field is used to indicate what version of IP is being used.

3. The IPv6 header field that indicates how many routers can forward a packet before it’s discarded is called the ________.

  • TTL
  • hop limit field (CORRECT)
  • next header field
  • router forward field

Right on! The hop limit field configures how many routers can try to forward a packet before it’s discarded.

QUIZ: IPV6 COMPRESSION

1. IPv6 Compression Rules

Exercise Objectives

Using the two rules of IPv6 compression, edit each IPv6 address until it is in the shortest form possible, then click ‘Check’. You have 10 addresses to compress.

1.

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(CORRECT)

2.

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(CORRECT)

3.

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(CORRECT)

4.

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(CORRECT)

5.

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(CORRECT)

6.

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(CORRECT)

7.

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(CORRECT)

8.

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(CORRECT)

9.

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(CORRECT)

10.

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COURSERA IPV6 COMPRESSION(CORRECT)

(CORRECT)

QUIZ: TROUBLESHOOTING AND THE FUTURE OF NETWORKING

1. When you send an echo request message with the ping program, a successful attempt will return a(n) ______ message.

  • pong
  • echo reply (CORRECT)
  • blank
  • error

Yep! A successful echo request will return an echo reply.

2. The Linux and macOS program traceroute is known by a slightly different name on Windows. It’s referred to as ______.

  • tracepath
  • ping
  • ipconfig
  • tracert (CORRECT)

You nailed it! These programs operate slightly differently and have slightly different names.

3. An organization responsible for assigning individual domain names to other organizations or individuals is known as a(n) ______.

  • DNS registrar (CORRECT)
  • internet authority
  • autonomous system
  • government

Wohoo! You can use a registrar to register a domain name!

4. IPv6 addresses beginning with FE80:: are used for ______.

  • public multicast
  • anycast
  • Network Address Translation
  • link local unicast (CORRECT)

You got it! Link-local unicast is used for IPv6 nodes to get their network configuration, much like DHCP.

5. The equivalent of the TTL field in an IPv4 header is known as the ______ field in an IPv6 header.

  • hop limit (CORRECT)
  • traffic class
  • next header
  • flow label

Yep! The hop limit field corresponds to the IPv4 TTL field.

6. A support technician uses the ping utility on a system that is online, yet no response is received. What

  • Echo reply
  • ICMP (CORRECT)
  • Echo request
  • TTL

You got it! The ping utility uses the Internet Control Message Protocol (ICMP).

7. Most public Domain Name Servers (DNS) are available globally through which technology?

  • Hosts file
  • Echo request
  • Time To Live (TTL) field
  • Anycast (CORRECT)

Awesome! Anycast is a method that pools servers to provide services as if it were a single system.

8. Which of these addresses is an Internet Protocol (IP) v4 loopback address?

  • 8.8.8.8
  • 127.0.0.1 (CORRECT)
  • 192.168.1.1
  • 1.2.3.4

Nice job! A loopback address points to itself and is used for troubleshooting purposes.

9. Which option is NOT provided with cloud storage?

  • Availability
  • Physical hardware (CORRECT)
  • Accessibility
  • Security

Right on! Cloud storage is Internet based disk space. Optional local physical disk space is provided by the user.

10. How many zeros are found at the beginning of an Internet Protocol (IP) v6 address that correlate to a v4 address?

  • 32
  • 128
  • 80 (CORRECT)
  • 40

Woohoo! Any IPv6 address that begins with 80 zeros and is then followed by 16 ones, is understood to be part of the IPv4 mapped address space.

11. When using the netcat command to test a network port, which option will provide output that is not useful for scripting, but is useful for the human eye?

  • -Port
  • -v (CORRECT)
  • -z
  • No option is required

Awesome! The “-v” flag, which stands for verbose, is useful as it formats the command’s output to be readable to human eyes.

12. When registering a new domain name, either the registrar’s servers or self-owned servers can be used as name servers. What function will the name servers provide for the domain?

  • Authoritative (CORRECT)
  • Address reservation
  • Error recovery
  • Domain transfer

Nice job! An authoritative name server is responsible for a Domain Name System (DNS) zone.

13. Which addresses represent valid local loopback addresses? Check all that apply.

  • 127.0.0.1 (CORRECT)
  • ::0
  • ::1 (CORRECT)
  • 255.255.255.255

Right on! The Internet Protocol address 127.0.0.1 is known as a v4 local loopback address.

Nice job! The Internet Protocol address ::1 is known as a v6 local loopback address.

14. Internet Protocol (IP) v6 addresses are written out in which format?

  • 8 groups of 12 bits
  • 6 groups of 32 bits
  • 4 groups of 16 bits
  • 8 groups of 16 bits (CORRECT)

Awesome! IPv6 addresses are usually written out as 8 groups of 16 bits each. Each of these groups is further made up of 4 hexadecimal digits.

15. What size is an Internet Protocol (IP) v6 payload field?

  • 32-bit
  • 20-bit
  • 16-bit (CORRECT)
  • 8-bit

Awesome! The payload length field is a 16-bit field that defines how long the data payload section of the datagram is.

16. The ability for a protocol or program to determine that something went wrong is known as ________.

  • redundancy
  • data verification
  • error detection (CORRECT)
  • data resilience

Awesome! Error detection is determining that an error occurred; error recovery is attempting to fix this error automatically.

17. An organization responsible for assigning individual domain names to other organizations or individuals is known as a(n) ______.

  • DNS registrar (CORRECT)
  • internet authority
  • autonomous system
  • government

Wohoo! You can use a registrar to register a domain name!

18. Following rules of compaction, the IPv6 address 2001:0db8:0000:0000:0000:ff00:0012:3456 could also be written as _______.

  • 21:db8::ff:12:3456
  • 2001:db8::ff00:12:3456 (CORRECT)
  • ::1
  • 0000:0000:0000:0000:0000:0000:0000:0001

Awesome! IPv6 address compaction is a great way to shorten IPv6 addresses.

19. Traceroute uses UDP packets on which of the following operating systems? Check all that apply.

  • Linux (CORRECT)
  • Windows 7
  • Windows 10
  • Mac OS (CORRECT)

Great work! On Linux and macOS, traceroute sends UDP packets to very high port numbers.

You got it! On Linux and macOS, traceroute sends UDP packets to very high port numbers.

20. A tech uses the netcat tool on a Linux system. Of the choices, which has proper syntax?

  • nc google.com -z
  • nc google.com 80 (CORRECT)
  • nc -v 80
  • nc google.com

You nailed it! The nc command requires that a host and a port are included.

21. As an IT decision maker, you plan to satisfy business needs by using software as a service. Which option do you deploy?

  • Office 365 (CORRECT)
  • Virtual firewall
  • Linux workstation
  • Windows Server 2019

You nailed it! Software as a Service (SaaS) is a model that uses cloud-based software, rather than locally installed software.

22. You would like to use the nslookup command in interactive mode. How is the mode accessed?

  • By providing a domain name with the command.
  • By providing a port number with the command.
  • By providing the command with no options. (CORRECT)
  • By providing the command with the interactive option

You nailed it! When using the nslookup command with no options, the command provides a prompt to enter additional information in what is called an interactive mode.

23. When the ping command is used, output is similar across operating systems. Which two values are displayed as part of the output? Check all that apply.

  • Port number
  • Round-trip time (CORRECT)
  • Message byte size (CORRECT)
  • Gateway address

Well done! Every line of output will generally display how long it took for the round-trip communications.

You got it! Every line of output will generally display how large the message is in bytes.

24. When shortening an Internet Protocol (IP) v6 address, which two rules are used? Check all that apply.

  • Replace groups of zeros with colons. (CORRECT)
  • Removing all leading zeros. (CORRECT)
  • Replace groups of ones with semicolons.
  • Removing all leading ones.

Woohoo! Any number of consecutive groups composed of just zeroes can be replaced with two colons

Nice job! When shortening an IPv6 address, you can remove any leading zeros from a group.

25. The ability for a protocol or program to determine that something went wrong is known as ________.

  • Internet Control Message Protocol (CORRECT)
  • Internet Client Message Protocol
  • Interactive Control Message Protocol
  • Internet Control Mail Protocol

Correct! ICMP is used to deliver messages about network errors.

26. One of Google’s public DNS servers is 8.8.8.8. The other one is ______.

  • 0.0.0.0
  • 255.255.255.255
  • 8.8.4.4 (CORRECT)

Awesome! 8.8.8.8 and 8.8.4.4 are useful IPs to memorize when troubleshooting.

27. The IPV4 mapped address space within IPv6 always starts with _______ zeroes.

  • 32
  • 64
  • 80 (CORRECT)
  • 128

Right on! 80 zeroes, followed by 16 ones, followed by the IPv4 address itself it how the IPv4 mapped address space works.

28. A Cyclical Redundancy Check (CRC) is an example of what type of built-in protocol mechanism? Check all that apply.

  • Time To Live (TTL) expiration
  • Misconfiguration error
  • Error detection (CORRECT)
  • Error recovery (CORRECT)

You got it! If a CRC value doesn’t match, it is discarded. The transport layer will decide if the data needs to be resent.

Right on! If a CRC value doesn’t match, it is discarded. The transport layer will decide if the data needs to be resent.

29. You need to find the Internet Protocol (IP) address for a website. Which command do you use on a Windows system?

  • netcat
  • pathping
  • ping
  • nslookup (CORRECT)

You got it! Using the nslookup command with a domain will return a host (A) record.

30. When troubleshooting Domain Name System (DNS) problems, which helpful feature do public servers usually support?

  • Virtualization services
  • Port connectivity
  • ICMP echo requests (CORRECT)
  • Paths between nodes

Woohoo! Public DNS servers usually support Internet Control Message Protocol (ICMP) echo requests. This is helpful when troubleshooting, while using the ping command.

31. A web developer requires an environment to perform application testing. Which cloud service type does the developer choose to use?

  • Virtualization service
  • Software as a Service
  • Infrastructure as a Service
  • Platform as a Service (CORRECT)

You got it! With a platform as a service environment, software applications can be developed, run, and tested without the concern for the underlying technologies

32. What is the name of the provision of services based around hardware virtualization?

  • Domain Name System (DNS) service model
  • Cloud computing (CORRECT)
  • Network Address Translation (NAT)
  • Subnetting

Correct: Great work! Hardware virtualization is a core concept of how cloud computing technologies work.

33. Which Internet Protocol (IP) v6 header field is used to determine the quality of service level for a datagram?

  • Flow label (CORRECT)
  • Next header
  • Payload length

Correct: Nice job! The flow label field is used in conjunction with the traffic class field for routers, to make decisions about the quality of service level for a specific datagram.

34. During a traceroute, which action does a router perform to the value in the Time To Live (TTL) field?

  • Addition
  • Division
  • Multiplication
  • Subtraction (CORRECT)

Correct: Awesome! The TTL field is decremented (subtracted) by one by every router that forwards the packet.

35. The IPv6 loopback address is _____.

  • 127.0.0.1
  • 0000:0000:0000:0000:0000:0000:0000:0000
  • 0000:0000:0000:0000:0000:0000:0000:0001 (CORRECT)

Correct: Correct! The IPv6 loopback address is a great example of how IPv6 address compaction works.

36. You need to prove ownership of a domain name for an upcoming transfer to a new registrar. Which Domain Name System (DNS) record do you create to prove ownership?

  • Canonical Name (CNAME)
  • Name Server (NS)
  • Service (SRV)
  • Text (TXT) (CORRECT)

Correct: Well done! To prove ownership of a domain name, a DNS TXT record is commonly used.

37. You run the Test-NetConnection command on a Windows PC while only providing a host name. As a result, what default action does the command use?

  • Network address translation
  • Echo request (CORRECT)
  • Private tunnel
  • Name server lookup

Correct: Great work! When running the Test-NetConnection command on a Windows PC and only providing a host name, an Internet Control Message Protocol (ICMP) echo request (ping) is used.

38. While in an interactive nslookup session, you’d use the ______ keyword to change the DNS server you’re using.

  • Server (CORRECT)
  • client
  • FQDN
  • DNS

Correct: Nice job! Issuing a server keyword, followed by a DNS server, will change what server you’re using for resolution attempts.

39. With virtualization, a single physical machine, called a host, can run many individual virtual instances, called ______.

  • clients
  • guests
  • servers (INCORRECT)
  • clouds

Correct: Correct! The IPv6 loopback address is a great example of how IPv6 address compaction works.

40. PaaS stands for ______.

  • Platform as a Service (CORRECT)
  • Packets as a Service
  • Preamble as a Service
  • Platform as a Schedule

Correct: Great job! PaaS enables you to run applications without requiring an entire server to do so.

41. A company runs sensitive technologies locally, while entrusting less-sensitive technologies to a broader user base. Which cloud delivery model is being used?

  • Public
  • Community
  • Hybrid (CORRECT)
  • Private

Correct: Great work! A combination of cloud delivery models make up a hybrid type of deployment. In this case, both private and public models are being used.

42. Which two tools function similar to traceroute? Check all that apply.

  • nslookup
  • pathping (CORRECT)
  • netcat
  • mtr (CORRECT)

Correct: Pathping runs for 50 seconds and then displays the final aggregate data all at once.

Correct: Right on! The mtr command works in real time and will continually update its output with all of the current aggregate data.

43. For all IPv6 addresses, the network ID is always the first ______ bits.

64 (CORRECT)

44. An organization responsible for assigning individual domain names to other organizations or individuals is known as a ______.

Registrar (CORRECT)

45. When you send an Echo Request message with the ping program, a successful attempt with return an ______ message.

echo reply (CORRECT)