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C.NETWORKING (CN 121) UE 2017-2018 SOLVED INTERACTIVE

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**Introduction to Computer Networking - Exam

2017/2018 ACADEMIC YEAR (SECOND SEMESTER)

THE UNIVERSITY OF DODOMA
COLLEGE OF INFORMATICS AND VIRTUAL EDUCATION
SCHOOL OF INFORMATICS
UNDERGRADUATE UNIVERSITY EXAMINATIONS
SECOND SEMESTER 2017/2018
TN 122: INTRODUCTION TO COMPUTER NETWORKING
Date: 06th July, 2018
Time Allocated: 3 Hours

Instructions:

  1. This examination consists of six questions.

  2. Attempt all questions from section A and only three questions from section B.

  3. All University of Dodoma examination regulations apply.

SECTION A (40 Marks)

Question One

Part A: Multiple choice Questions (1 Mark Each)

1. Layering is commonly used in computer networks because:

  • A. It forces all network software to be written in ANSI ‘C’.
  • B. Encapsulation is the lowest overhead method to transmit data.
  • C. It allows widespread code and implementation re-use.
  • D. It keeps networks warm enabling them to run faster.

2. A message is sent to all hosts on a remote network. Which type of message is it?

  • A. Limited Broadcast
  • B. Unicast
  • C. Multicast
  • D. Direct Broadcast

3. In an Ethernet network, which of the following are true:

  • A. Ethernet switches learn addresses by looking at the destination address of packets as they pass by.
  • B. Ethernet hubs and repeaters learn addresses by looking at the addresses of packets as they pass by.
  • C. A correctly operating Ethernet switch never sends a packet to the wrong outgoing port
  • D. Ethernet switches learn addresses by looking at the source address of packets as they pass by.

4. The frequency of failure and network recovery time after a failure is measures of the ______ of a network.

  • A. Performance
  • B. Security
  • C. Feasibility
  • D. Reliability

5. An IPv6 address can have up to ______ hexadecimal digits

  • A. 16
  • B. 8
  • C. 128
  • D. 32

6. If your computer has the IP address 128.96.10.123, and the subnet mask is set to 255.255.0.0, your computer will connect directly to all computers whose IP address starts with ______.

7. Which network design consideration would be more important to a large corporation than to a small business?

  • A. Internet Router
  • B. Firewall
  • C. Low Port Density Switch
  • D. Redundancy

8. An employee at a branch office is creating a quote for a customer. In order to do this, the employee needs to access confidential pricing information from internal servers at the Head Office. What type of network would the employee access?

  • A. An Internet
  • B. An Extranet
  • C. An Intranet
  • D. A Local Area Network

9. Which layer of the OSI model is responsible for specifying the encapsulation method used for specific types of media?

  • A. Application
  • B. Transport
  • C. Data Link
  • D. Physical

10. Given the IP address 192.168.10.5. In the Network block in which the just mentioned address belong there are 3 printers that need to use reserved static IP addresses from the address pool. How many IP addresses in the pool are left to be assigned to other hosts?

  • A. 254
  • B. 252
  • C. 251
  • D. 253

Part B: True and False Questions (1 Mark Each)

1. When a device is sending data to another device on a remote network, the Ethernet frame is sent to the MAC address of the default gateway.

2. WANs connect LANs at slower speed bandwidth than LANs connect their internal end devices.

3. Hubs are considered to be fairly unsophisticated devices, since they inefficiently rebroadcast all traffic on every port.

4. One of the characteristics of Circuit Switched Networks is that; if all circuits are busy, a new call cannot be placed.

5. The Ping command is used on a Windows PC to see the IP configuration of that computer.

6. The PDU format used when bits are received from the network medium by the NIC of a host is called a segment.

7. The organization responsible for overseeing and managing IP address allocation, domain name management, and protocol identifiers is called IETF.

8. 802.11a can give a speed of up to 54Mbps; the only problem with it is the backward compatibility with the earliest versions.

9. Among the 4 pairs of UTP cable, White-Orange Pair is used for Transmission of signals while White-Green Pair is used for Reception.

10. The two main functions of an Internet Protocol router are the forwarding of individual packets and the maintenance of routing tables.

Part C: Short Answers Questions (1 Mark Each)

1. DHCP uses UDP port number ______ for sending data to the server.

2. If link transmits 4000frames per second, and each slot has 8 bits, the transmission rate of circuit this TDM is ______.

3. In the transfer of file between server and client, if the transmission rates along the path is 10Mbps, 20Mbps, 30Mbps, 40Mbps. The throughput is usually ______.

4. Given the IP address 146.34.256.78; the Network ID in which the address belong is ______.

5. Sometimes we refer to it as a microwave repeater in space; ______.

6. There are two connection types as long as cable termination to RJ-45 is concerned. Among the two, which one is used when connecting a router and a router?

7. Given the IP address 198.251.45.99, this address belongs to class ______ and its hexadecimal equivalence is ______.

8. An endpoint of an inter-process communication flow across a computer network is called a ______ destination.

9. The three layers of Fiber Optic cable are Plastic socket, glass or plastic cladding and ______ fiber core.

10. If 10 nodes are communicating using a Hub on a 20-Mbps network, then what will each node get as far as bandwidth is concerned?

Question Two

a. Why the IPv6 while we already have IPv4? (1 Marks)

b. Perform the following conversion between the below notations (2 Marks Each)

i. 10001111 01110000 11111110 10101010 to Decimal Notation

ii. 176.67.249.189 to Hexadecimal Notation

iii. 0XAB671DCF to Decimal Notation

c. Given the IP address 219.45.78.138; answer the below questions (1 Mark Each)

i. What is the Network ID of the block in which the given address belong?

ii. The range of addresses in the block

iii. The usable range of addresses in the block

SECTION B (60 Marks)

Question Three

a. With examples discuss and compare LAN, MAN and WAN (6 Marks)

b. Briefly explain the roles of the below-listed devices in computer networking (5 Marks)

i. Repeater

ii. Bridge

iii. Switch

iv. Router

v. Gateway

d. Differentiate between Internet, Extranet and Intranet. (5 Marks)

Question Four

a. Mention the three reasons of having a LAYERED OSI Model (3 Marks)

b. Mention the 4 TCP/IP Layer. (2 Marks)

c. Starting from the first layer to the last one; list the OSI layers providing in brief the function of each layer. (6 Marks)

d. Briefly describe how collision are avoided in the below-listed LAN technologies:

i. Ethernet (2 Marks)

ii. Token Passing (2 Marks)

Question Five

a. Mention five design factors when choosing a networking transmission media. (5 Marks)

b. What does STP offers more compared to UTP? (2 Marks)

c. Mention two advantages and two disadvantages of Twisted pair wires. (4 Marks)

d. What is the fundamental difference between the Single-mode Fiber and Multi-mode fiber? Explain the rule of thumb governing the relationship between the earlier said difference and the fiber’s bandwidth and the attenuation. (4 Marks)

e. Mention two advantages and two disadvantages of Fiber Optic cable. (4 Marks)

Question Six

a) Why do we need to have security in computer networks? (2 Marks)

b) Briefly explain the security goals. (3 Marks)

c) With the help of diagrams, explain brief the 4 types of security attack. In your explanation you must specify the security service being compromised in each of the attack and also which among the attacks are active as well as passive. (8 Marks)

d) Briefly explain only three common security attacks you are aware of; a mitigation strategy should be provided for each of the explained attack. (6 Marks)

END OF EXAMINATION PAPER

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