Chapter 1 - Introduction to Computer Networks (Questions/Answers)

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Chapter 1 - Introduction to Computer Networks (Questions/Answers)

Questions and Problems
Section 1-1

1. State whether the following network descriptions are describing a MAN, WAN, or LAN:
        a. A network of users that share computer resources in a limited area.
        b. A network of users that share computer resources across a metropolitan area.
        c. A network that connects local area networks

        a. LAN
        b. MAN
        c. WAN

2. Expand the acronym NIC.
        i. “Network Interface Card”

3. Expand the acronym MAC.
        i. “Media Access Control”

4. Expand the acronym LAN.
        i. “Local Area Network”

5. Expand the acronym WAN.
        i. “Wide Area Network”

Section 1-2

6. Define the term protocol.
        i. Set of rules established for users to exchange information.

7. Define the term topology.
        i. Architecture of a network.

8. Define the term deterministic.
        i. Access to the network is provided at fixed time intervals

9. A disadvantage of the token-ring system is that if an error changes the token pattern, it can cause the token to stop circulating. This can be eliminated by adding a  . . .
       d. Token-ring hub (A hub that manages the passing of the token in a Token-Ring network.)

10. State the network topology being used in the following figures (Bus, Star, Ring, or Mesh).
       a. Mesh
       b. Bus
       c. Ring
       d. Star

11. What is the difference between a hub and a switch?
       i. Hub – Broadcasts data it receives to all devices connected to its ports.
      ii. Switch – Establishes a direct connection from the sender to the destination without passing the data traffic to other networking devices.

Section 1-3

12. Define the acronym CSMA/CD and the protocol that uses CSMA/CD.
       i. “Carrier Sense Multiple Access with Collision Detection”
      ii. The networking protocol “Ethernet”.

13. What information is not included in an Ethernet frame?
      a. Frame size

14. What is the minimum size of the data payload in an Ethernet frame?
       i. 46 bytes
      ii. The data being transmitted, followed by the pad that is used to bring the total number of bytes up to the minimum of 46 if the data field is less than 46 bytes.

15. What is the minimum and maximum size of an Ethernet frame?
      i. Minimum – 64 bytes
     ii. Maximum –  1518 bytes

16. Define the acronym OUI. Where is the OUI used?
      i. “Organizationally Unique Identifier”
     ii. The first 3 bytes, 24 bits, or 6 digits of a MAC address.

17. What does the OUI represent?
      i. The vendor of the NIC “Network Interface Card”

18. In Windows Vista or Windows XP, how would you find the Ethernet (MAC) address?
      i. Selecting Start and then Run. In the Run window enter “cmd” and click OK. In the command prompt window that displays enter the command “ipconfig  /all” and hit Enter. The MAC address is listed under Ethernet adapter Local Area Network. The MAC address is labeled as the Physical Address.

19. INTERNET SEARCH: Find the device manufacturer for the following Ethernet devices:
     a. 00-C0-4F-49-68-AB – DELL
     b. 00-0A-27-B7-3E-F8 – APPLE
     c. 00-04-76-B6-9D-06 – 3Com
     d. 00-00-36-69-42-27 – ATARI

20. State the class of address (A, B, or C) for the following IP addresses:
     a. – Class A
     b. –  Class C
     c. –  Class C
     d. –  Class A
     e. – Class A
     f. – Class B

21. Expand the acronym TCP/IP.
     i. “Transmission Control Protocol/ Internet Protocol”

Section 1-4

22. Cite the three advantages of a wired network.
     i. Faster network data transfer speeds (within the LAN)
     ii. Relatively inexpensive to setup
     iii. The network is not susceptible to outside interference.

23. Cite three advantages of a wireless network.
     i. User mobility
     ii. Simple installations
     iii. No cables

24. What does it mean for a wireless networking device to be Wi-Fi compliant?
     i. That the device has been tested by the Wi-Fi Alliance (Wireless Fidelity) and is certified for compliance with 802.11x wireless standards.

25. What are the most common types of equipment that are used to establish a broadband connection to the ISP?
     i. Cable Modem
     ii. DSL Modem

26. Name six issues that should be considered when planning a home network?
     i. Data Speed – “Wired of Wireless?”
     ii. Cost – “Cost of equipment?”
     iii. Ease of Implementation– “Cables already ran? Wireless setup is usual minimal.”
     iv. Appearance– “Wireless networks are neater with no cables.”
     v. Home Access– “Wireless for mobility, but wired for faster transfer rates.”
     vi. Public Access– “ISP is the limiting factor for the data transfer rate for the public access.”

27. Why is checking the lights of a networking device that connects to the ISP important?
     i. Link Verification will typically appear as a Lit Link Light.
     ii. The presence of a link light indicates that the transmit and receive pairs are properly aligned and the connected devices are communicating.
     iii. Absence of the light indicates a possible cabling or hardware problem.

28. What is the purpose of a Range expander?
     i. The wireless signal might not be reaching all the areas that need coverage.
     ii. The device relays the wireless signals from an access point or wireless router into areas with a weak signal or no signal at all.
     iii. Range Extender – Device that relays the wireless signals from an access point or wireless router into areas with a weak signal or no signal at all

29.  What is a hotspot?
     i. A limited geographic area that provides wireless access for the public.

30. List five steps that can be used to protect the home network.
     i. Change the default factory passwords.
     ii. Change the default SSID. “Service Set Identifier”
     iii. Turn on encryption.
     iv. Turn off the SSID broadcast.
     v. Enable MAC address filtering.

31. You have the choice of selecting a networking device with WEP and another with WPA. Which offers better security and why?
     a. WPA - Basically put it’s an upgrade overlay for WEP.
     b. WPA uses Temporal Key Integrity Protocol (TKIP). TKIP is designed to allow WEP to be upgraded. This means that all the main building blocks of WEP are present, but corrective measures have been added to address security problems.

32. What are the potential problems of using the default factory passwords?
     i. They are known to the public.
     ii. Security hole for public access to your network.

33. What is the purpose of the SSID, and what can the network administrator do to protect the network from hackers who might have learned the SSID?
     i. The purpose of the SSID is to identify your wireless network and is used by your access point or wireless router to establish an association.
     ii. The network administrator can change it periodically and turn off broadcasting it in the device’s menu.

34. What is the purpose of MAC filtering on a wireless network?
     i. Only wireless devices that have specific MAC addresses will be allowed access to the network.

35. How does NAT (Network Address Translation) help protect outsider access to computer in the home network?
     i. NAT translates the private IP address to a public address for routing over the Internet.
     ii. Private IP address being –,,
     iii. Public IP address being the ISP issuing an IP address to the router from an available pool of IP addresses manage by the ISP.

36. What is Stateful Packet Inspection “SPI”?
     i. A type of firewall protection that inspects incoming data packets to make sure they correspond to an outgoing request.

37. What is a VPN, and how does it protect the data transferred over a wireless network?
     i. A VPN is a Virtual Private Network and it establishes a secure network connection and is a way to protect your LAN’s data from being observed by outsiders.
     ii. A VPN enables a remote or mobile user to access the network as if they were actually physically at the network.
     iii. The VPN connection is encrypted, providing privacy for the data packets being transmitted.

38. How is IP addressing typically handled in a home network?
     i. Is managed by the router or wireless router that connects to the ISP.
     ii. The ISP will issue an IP address to the router from an available pool of IP addresses manage by the ISP.
            i. The computers on the network should then be issued private IP addresses using NAT “Network Address Translation”.

39. What is Port Address Translation “PAT”?
     i. A port number is tracked with the client computer’s private address when translating to a public address.
     ii. When you are assigned a private address with NAT “Network Address Translation” there is no way for the router to pinpoint the specific computer because it uses the same address for all computers. With PAT “Port Address Translation” the router uses the port number to identify the computer that accessed the internet and delivers the data packet to the right computer.

40. A router on a home network is assigned an IP address of A computer in the home network is assigned a private IP address of The computer is assigned the public IP address Which IP address is used for routing data packets on the internet? Is overloading being used?
     i. is being used for routing data packets on the internet.
     ii. Overloading is being used when the computer was assigned a private address and started sending data packets, which after the packets reach the router and are then sent using the public address assigned to the router by the ISP.

Section 1-5

41. Which of the following is not a step in building an office LAN?
     a. Obtaining proper government permits

42. What does RJ-45 represent?
     c. An 8-pin modular connector for twisted pair Ethernet

43. What is an uplink port?
     i. Allows the connection of a hub or switch to another hub or switch without having to use a crossover cable.

44. What is the maximum speed and length for Category 6 cabling?
     i. Maximum Speed – 1000 Mbps
     ii. Maximum Length -  100 Meters

45. What do the link lights on a hub represent?
     i. The presence of a link light indicates the transmit and receive pairs are properly aligned and the connected devices are communicating.
     ii. Absence of the light indicates a possible cabling or hardware problem.

46. What does cross-connected mean?
     i. Transmit and receive signal pairs are crossed to properly align the transmit signal on one device with the receive signal on the other device.

47. Documentation: Draw a network diagram similar to Figure I-26 consisting of 3 computers, a switch, and a printer. Use the MAC addresses given in Table I-6. Assign each network device an IP address from the private address space 192.168.5.x network. You are the network administrator and may choose the host address for each device.

Section 1-6

48.What command would you use to ping indefinitely?
     i. ping –t

49.What command would you use to ping 20 times with 1024 bytes of data?
     i. ping –n 20 -l 1024

50. Expand the acronym TTL.
     i. “Time To Live”

Section 1-7

51. Expand the acronym ARP.
     i. Address Resolution Protocol
52. What is the purpose of an ARP request?
     i. They are used to map an IP address to its MAC address
53. Expand the acronym ICMP.
     i. Internet Control Message Protocol
54. What is an echo request?
     i. Part of the ICMP protocol that requests a reply from a computer.
55. What is the purpose of a protocol analyzer?
     i. A protocol analyzer is used to inspect captured data packets.
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