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C.NETWORKING (CN 121) UE 2023-2024 SOLVED INTERACTIVE

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**Introduction to Computer Networking - Exam

THE UNIVERSITY OF DODOMA COLLEGE OF INFORMATICS AND VIRTUAL EDUCATION
Department of Computer Science and Engineering

End of Semester Two University Examination for the 2023/2024 Academic Year

  • Course Name: Introduction to Computer Networking
  • Paper Code Number: CN 121/CN 120
  • Date of Examination: 2nd July 2024
  • Time: 11:45 – 14:45
  • Duration: 3 Hours
  • Venue(s): AUDITORIUM, ELL, LRB 105, LRB 004D, LDR005B, CBSL_AB2_LR01, CBSL_AB1_LR01, CBSL_AB1_LR02, EDU THEATRE 4
  • Sitting Programme(s): BSc. TE1, CE1, BIS1, IDIT1, IS1, CNISE1, CSDFE1, MTA1, SE1, CS1, DCBE1, BCOMM1, BAKSET1, BAEEP1, and RED SCIENCE_ICT3

SECTION A: (40 MARKS)

Answer ALL questions in this section.

Question One

Choose the most correct answer.

i. Which one of the following is a true statement about ARP poisoning or MAC spoofing?

  • A. MAC spoofing is used to overload the memory of a switch
  • B. ARP poisoning is used to falsify the physical address for a system to impersonate that of another authorized device.
  • C. MAC spoofing relies on ICMP communication to traverse routers.
  • D. ARP poisoning can use unsolicited or gratuitous replies.

ii. Jim was tricked into clicking on a malicious link contained in a spam email message. This caused malware to be installed on his system. The malware initiated a MAC flooding attack. Soon, Jim’s system and everyone else’s in the same local network began to receive all transmissions from all other members of the network as well as communications from other parts of the next-to-local members. The malware took advantage of what conditions in the network?

  • A. Social engineering
  • B. Network segmentation
  • C. ARP queries
  • D. Weak switch configuration

iii. Ethernet frame consists of ______

  • A. MAC address
  • B. IP address
  • C. Default mask
  • D. Network address

iv. A ______ firewall is able to make access control decisions based on the content of communications as well as the parameters of the associated protocol and software.

  • A. Application-level
  • B. Stateful inspection
  • C. Circuit-level
  • D. Static packet filtering

v. In the OSI model, when data is sent from device A to device B, the 5th layer to receive data at B is

  • A. Application layer
  • B. Transport layer
  • C. Link layer
  • D. Session layer

vi. How many hosts on a half-duplex segment can talk at one time?

  • A. Zero
  • B. One
  • C. Two
  • D. Unlimited

vii. You need a network that provides centralized authentication for your users. Which of the following logical topologies should you use?

  • A. VLANs
  • B. Peer-to-peer
  • C. Client-server
  • D. Mesh

viii. What type of network must a home user access in order to do online shopping?

  • A. An intranet
  • B. The internet
  • C. An extranet
  • D. A local area network

ix. In the layer hierarchy as the data packet moves from the upper to the lower layers, headers are

  • A. Added
  • B. Removed
  • C. Rearranged
  • D. Modified

x. Which of the following is an example of a PC LAN access protocol?

  • A. TCP/IP
  • B. NetBEUI
  • C. Ethernet
  • D. Token Bus

Question Two

Match the item in Column A with its corresponding item in Column B.
(1 Mark Each)

Column A i. The distortion of a transmitted message due to signals carried in adjacent wires ii. The measure of the usable data transferred across media over a given period of time iii. Converts text-based addresses to and from IP iv. Standard protocol for the Internet v. Broken-down parts of a message sent over the Internet vi. An attempt to make a computer resource unavailable to its intended users vii. Port address viii. Wireless connection that uses light waves over short distances ix. It identifies the device physically in the network. x. Cable that transmits data as pulses of light

Column B

  • A. DNS
  • B. MAC address
  • C. Packets
  • D. Fiber cable
  • E. Internet Protocol
  • F. Throughput
  • G. Fiber optic
  • H. TCP/IP
  • I. Attenuation
  • J. IP address
  • K. Wi-Fi
  • L. Latency
  • M. Infrared
  • N. Ethernet
  • O. Denial of service
  • P. TCP/UDP
  • Q. Interference

Question Three

Write TRUE for correct statement and FALSE for incorrect statement.
(1 Mark Each)

i. An extranet is a network that uses Internet technologies to allow access to invited users from outside the organization.

ii. Infrared rays penetrate through walls.

iii. The data link layer is responsible for end-to-end frame delivery.

iv. Optic fibers is one example of copper cabling used in LANs.

v. Delimiting and synchronization of data exchange is provided by session layer.

vi. Microwave transmissions are a line-of-sight medium.

vii. Session layer defines the format in which the data is to be exchanged between the two communicating entities.

viii. A network architecture provides the blueprint for designing and implementing a network.

ix. The transport layer routes messages through the network selecting the best path from the source to the destination station.

x. In star topology every node has a direct connection to every other node in the network.

Question Four

a. For each of the following, identify the network devices (hub, switch, repeater, router, bridge, NIC) that most closely match the specified characteristics.
(1 Mark Each)

i. This device sends and receives information about the Network layer.

ii. This device uses hardware addresses to filter a network.

iii. This device creates one big collision domain.

iv. A network device that is used to connect multiple devices together without segmenting a network.

v. A network device that provides the physical, electrical, and electronic connections to the network media.

b. For each of the following function, identify the OSI layer responsible for each function.
(1 Mark Each)

i. Bit-by-bit delivery in the network.

ii. Establishing, maintaining and synchronizing the interaction between communicating devices.

iii. Physical addressing in the network.

iv. Translation, decryption and compression of information.

v. Provides the network services to the end-users.

SECTION B: (60 MARKS)

Attempt any THREE (3) out of FOUR (4) questions provided.

Question Five

(20 Marks)

a. Name two types of connectors that are used for each of the following cables:
(2 Marks Each)

i. UTP

ii. Fibre cable

b. A small office has twelve (12) workstations that need to be connected. The office also has three (3) printers that need to be accessible to all workstations.

i. Determine the network topology and the number of links required if:
(3 Marks Each)

a. All workstations and printers are connected in a fully meshed topology.

b. A central switch is used to connect all workstations and printers.

ii. The workstations are equally distributed into 3 groups, with each group connected to one of the 3 printers using a star topology forming a network segment. Suppose that the network segments are fully interconnected with the others.

a. Sketch the network topology.
(3 Marks)

b. Determine the number of links in it (a).
(3 Marks)

c. What name best suit the topology in it (a)?
(3 Marks)

d. How many collision domains are in the network?
(3 Marks)

Question Six

(20 Marks)

a. What is the subnet address if the destination address is 100.45.34.0 and the subnet mask is 255.255.240.0?
(2 Marks)

b. Your router has the following IP address on Ethernet: 172.16.2.1/23. Determine two valid addresses that can be valid host IDs on the LAN interface attached to the router.
(2 Marks)

c. What is the maximum number of IP addresses that can be assigned to hosts on a local subnet that uses the 255.255.255.224 subnet mask?
(3 Marks)

d. You need to subnet a network that has 5 subnets, each with at least 16 hosts. Which subnet mask would you use?
(3 Marks)

e. A company is granted the site address 181.56.0.0. The company needs 1000 subnets. Design the subnets.
(6 Marks)

f. A network administrator is connecting hosts A and B directly through their Ethernet interfaces, as shown in figure 1. Ping attempts between the hosts are unsuccessful. What can be done to provide connectivity between the hosts?
(4 Marks)

Question Seven

(20 Marks)

a. Define Network security.
(1 Mark)

b. CIAAN provides the core security properties that are used to ensure the security and reliability of information systems including network infrastructure. Describe each concept showing its relevance in securing the network infrastructure.
(5 Marks)

c. Informatics Insurance Company is a firm with its main offices at Dodoma, supporting 300 staff at the headquarters, and 400 staff at the different branches across the country. The company board has decided to revamp the current network at its HQ, and install a new network infrastructure, offering resilient and secure services. You have been hired as a network security consultant to identify threats and propose necessary mitigation mechanisms. Use the TCP/IP model as a guide to accomplish your assignment.
(14 Marks)

Question Eight

(20 Marks)

a. What is the name of a Windows command line utility that can be used to display TCP/IP configuration settings?

b. Which two commands in MS Windows are used for resetting the IPv4 DHCP configuration settings for all adapters?

c. A command line utility in MS Windows used for displaying protocol statistics and current TCP/IP network connections is called?

d. Which command in MS Windows is used to display the contents of a routing table?

e. Which option allows for execution of a command if the requested operation in the command line interface in MS Windows requires elevation?

f. What is the name of a command line utility used for checking the reachability of a remote host?

g. Which command in MS Windows is used to display help information related to a specific network command line utility?

h. A network command line utility in MS Windows that tracks and displays the route taken by IPv4 packets on their way to another host is called?

i. Which command in MS Windows displays a table consisting of IP addresses and their resolved Ethernet physical addresses?

j. Which command allows for obtaining a domain name to IP address mapping in MS Windows?

END OF EXAMINATION PAPER

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