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C.NETWORKING (CN 121) UE 2016-2017 SOLVED INTERACTIVE

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**Introduction to Computer Networking - Exam

2016/2017 ACADEMIC YEAR (SECOND SEMESTER)

THE UNIVERSITY OF DODOMA
COLLEGE OF INFORMATICS AND VIRTUAL EDUCATION
SCHOOL OF INFORMATICS
UNDERGRADUATE UNIVERSITY EXAMINATIONS
SECOND SEMESTER 2016/2017
TN 122: INTRODUCTION TO NETWORKING
Date: 7 July, 2017
Time Allocated: 3 Hours

Instructions:

  1. This examination consists of six questions.
  2. Answer only FOUR questions; Section A is compulsory and any other two (2) questions from section B.
  3. Do not use this examination paper for rough work. All rough work must be done in the answer book last page
  4. All University of Dodoma examination regulations apply.

SECTION A (40 Marks)

Question One

A: Multiple Choice questions (1 Mark Each)

i. FDDI uses which type of physical topology?

  • A) Bus
  • B) Ring
  • C) Star
  • D) Mesh

ii. Loss in signal power as light travels down the fiber is called?

  • A) Propagation
  • B) Attenuation
  • C) Scattering
  • D) Interruption

iii. Which color coding of cable is used to connect similar devices?

  • A) Straight cable
  • B) Crossover cable
  • C) Serial cable
  • D) All mentioned

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

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

v. In OSI model dialogue control and token management are responsibilities of what layer?

  • A) Physical Layer
  • B) Presentation Layer
  • C) Application Layer
  • D) Session Layer

vi. MAC address is of

  • A) 24 bits
  • B) 36 bits
  • C) 42 bits
  • D) 48 bits

vii. Bluetooth transceiver devices operate in ______ band.

  • A) 2.5GHz
  • B) 2.6GHz
  • C) 5GHz
  • D) 2.4GHz

viii. Message ______ means that the data must arrive at the receiver exactly as sent.

  • A) Confidentiality
  • B) Availability
  • C) Authentication
  • D) Integrity

ix. Switch is a device which operates at what layer?

  • A) Physical
  • B) Data Link
  • C) Network
  • D) Transport

x. In IPV 4, the IP address (200,345/200,200) belongs to

  • A) Class A
  • B) Class B
  • C) Class C
  • D) None mentioned

B: True and False Questions: (Write T for True and F for False) (1 mark Each)

i. Because all systems on the bus network connect to a single backbone, a break in the cable prevents all systems from accessing the network.

ii. Coaxial cable supports TV signals only.

iii. UDP is a connection-oriented protocol that creates and verifies a connection with a remote host before sending information.

iv. An IPv4 packet sent to all workstations on the network is called a Multicast.

v. In Circuit switching type of network; data is broken up into packets before it’s sent over the network?

vi. Like a virus, a worm needs the user to perform an action such as starting a program or opening an e-mail attachment to start the infection.

vii. Three security goals are Confidentiality, Integrity and Authentication.

viii. The network interface card converts serial data from the computer into parallel data for transmission over the network cable.

ix. A LAN becomes a WAN when you expand the network configuration beyond your own premises and must lease data communication lines from a public carrier.

x. The most fundamental differences between SM and MM Optic Fibers are the size of the fiber’s core and the associated attenuation or loss and bandwidth of the fiber

C: Short Answers Questions (1 Mark Each)

i. Which layer among the OSI layers is responsible for data compression and encryption?

ii. What is the frequency range used by 802.11a?

iii. Given (11111011\ 01101111\ 11111011\ 01001111); Give out its dotted-decimal notation.

iv. Mention the topology in which each computer on the network connects to every other, creating a point-to-point connection between every device on the network.

v. Mention the TCP/IP architecture layer which makes use of ports?

vi. Name the authority that oversees global IP address allocation.

vii. How long is an IPv6 address as far as bits are concerned?

viii. Mention three “versions” of Ethernet available for commercial use.

ix. Name the OSI Layer that covers all mechanical, electrical, functional and procedural aspects.

x. What is the subnetwork address if the destination address is 200.45.34.56 and the subnet mask is 255.255.240.0?

xi. As far as Transmission rate is concerned; which is much faster between 802.11a and 802.11b?

xii. When it comes to Port Address, which port number does HTTP use?

xiii. Given a class C IP address, you need to subnet a network that has 12 subnets, each with at least 10 hosts. Which subnet mask would you use?

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

xv. With Ethernet there is either straight through or crossover connections; what connection between the two is used when connecting two switches using their normal ports?

Question Two

a) What was a major motive towards IPv6? (2 Marks)

b) Convert listed IP address into binary notation; in your conversion include the class where each address belongs. (2 Marks Each)

i. 149.12.164.42

ii. 45.13.4.209

iii. 251.126.63.223

iv. 122.17.167.222

c) UDOM is granted the site address 207.168.45.0; the university has 6 colleges of which each one has its own network. Design the subnets. In your design you must show the following (15 Marks)

i. The subnet mask ii. The number of addresses in each subnet iii. In each subnet determine the start address, range of usable IP address and the broadcast address.

SECTION B (40 Marks)

Question Three

a) Define Computer Networking; provide two arguments in favor of the use of a computer network in an organization and one argument against. (4 Marks)

b) Using their definitions, give the difference between LAN, MAN & WAN (include example of each case). (6 Marks)

c) List only 4 design factors to be looked at when choosing a networking media. (4 Marks)

d) Write short notes about the listed topologies (include diagrams in your notes) (2 Marks Each)

i. Star Topology

ii. Mesh Topology

iii. Ring Topology

Question Four

a) Why protocols in computer networking? (2 Marks)

b) Why Layered Model in ISO’s OSI Model; Provide 4 reasons. (4 Marks)

c) List the seven layers of ISO’s OSI model starting from layer number 1, when listing briefly explain the function of each layer (the order of arrangement should be adhered) (8 Marks)

d) Briefly explain how the collision is avoided in the below listed LAN technologies i. Ethernet (3 Marks)

ii. Token Ring (3 Marks)

Question Five

a) Define the following i. Security Attack (1 Mark)

ii. Security mechanism (1 Mark)

iii. Security service (1 Mark)

b) Is worm the same as virus? Provide briefly explanation (1 Mark)

c) Provide brief explanation on why do we need Computer Network Security. (4 Marks)

d) With diagrams, list the four types of security attacks. (6 Marks)

e) Briefly explain 3 ways one can implement security defense mechanism. (2 Marks Each)

Question Six

a) Provide reason on why copper cable used as data transfer media are always twisted? (2 Marks)

b) List 2 advantages and 2 disadvantages of Fiber optic cable. (4 Marks)

c) Mention two advantages and 2 disadvantages of twisted pair. (4 Marks)

d) Outline the two limitations of star topology. (2 Marks)

e) What are Hubs? Briefly explain its types. (3 Marks)

f) Mention 5 design factors one needs to look upon when choosing transmission media (5 Marks)

END OF EXAMINATION

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