EC16503- COMPUTER NETWORKS

UNIT-I

UNIT I DATA COMMUNICATION AND PHYSICAL LAYER

Data Communication - Components - Data flow; Networks - Criteria- Physical Structure - Topology -
OSI Model- Transmission Impairment- Transmission media: Guided media -Twisted pair cable-
Coaxial cable- Fiber optic cable- Unguided media - Switching - Circuit switching networks - Packet
switching networks.

Multiple Choice Questions

1).It is a set of protocols that allows two different systems to communicate regardless of the
underlying technology.

a) Open system model

b) International standards Organisation
c) Transmission Control protocol
d) User Datagram protocol

2) Which layer is responsible for Framing, Flow Control and Error Control
a)Physical Layer
b)Data Link Layer
c)Network Layer
d)Session Layer

3) Which layer is responsible for encryption and decryption

a)Session Layer
b)Application Layer
c)Transport Layer
d)Presentation Layer

4) Which of the following layer of OSI model also called end-to-end layer?
a) Presentation layer
b) Network layer
c) Session layer
d) Transport layer
5) Which of the following protocol is/are defined in Transport layer?
a)FTP
b)TCP
c) UDP
d) B & C

6) Which data communication method is used to transmit the data over a serial communication link?

A. Simplex
B. Half-duplex
C. Full duplex
D. All of above

7) Which of the following is not the possible ways of data exchange?

A. Simplex
B. Multiplex
C. Half-duplex
D. Full-duplex

8).Router operates in which layer of OSI Reference Model?

A. Layer 1 (Physical Layer)

B. Layer 3 (Network Layer)
C. Layer 4 (Transport Layer)
D. Layer 7 (Application Layer)

9)What does protocol defines?

A. Protocol defines what data is communicated.

B. Protocol defines how data is communicated.
C. Protocol defines when data is communicated.
D. All of above

10)Coaxial cable consists of _______ concentric copper conductors.

 A. One
B. Two
C. Three
D. Four

11) Physical or logical arrangement of network is

A. Networking
B. Topology
C. Routing
D. None of the above.

12) In this topology there is a central controller or hub

A. Star
B. Bus
C. Mesh
D. Ring

13) In _________ resources are allocated on demand.

A. Packet switching
B. Circuit switching
C. Line switching
D. Virtual Switching

14) A local telephone network is an example of a _______ network

A. Packet switching
B. Circuit switching
C. Both A and B
D. Virtual Switching

15) If there are N routers from source to destination, total end to end delay in sending packet
P(L->number of bits in the packet R-> transmission rate)

A. N
B. (N*L)/R
 C. (2N*L)/R
D. L/R

16) Which cable consists of an inner copper core and a second conducting outer sheath.

A. Twisted-pair
B. Coaxial
C. Fiber-Optic
D. Shielded twisted-pair

17) In fiber optics, the signal is _______ waves.

A. Light
B. Radio
C. Infrared
D. Very low frequency

18) Which of the following primarily uses guided media?

A. cellular telephone system

B. local telephone system
C. Satellite Communications
D. Radio Broadcasting

19). What is the major factor that makes coaxial cable less susceptible to noise than twisted-pair
cable?

A. inner conductor
B. diameter of the cable
C. Outer conductor
D. Insulating material

20) In an optical fiber, the inner core is _______ the cladding.

A. denser than
B. less dense than
C. the same density as
D. another name for
21) _______ cable is used for voice and data communications.

A. Coaxial
B. Fiber-optic
C. Twisted-pair
D. none of the above

22) _____ cable can carry signals of higher frequency ranges than _____ cable.

A. Twisted-pair; fiber-optic

B. Coaxial; fiber-optic
C. Coaxial; twisted-pair
D. none of the above.

23) Signals with a frequency below 2 MHz use propagation.

A. ground
B. sky
C. line-of-sight
D. none of the above

24) Radio waves are

A. unidirectional
B. omnidirectional
C. bidirectional
D. directional

25) ________ are used for short-range communication between PC and a peripheral device.

A. radio waves
B. microwaves
C. Infrared
D. none of the above

26) Circuit Switching takes place at which layer

A. physical
B. network
 C. transport
D. data line

27) In which switching, the resources need to be reserved during the set up phase and remains
dedicated throughout the data transfer phase until tear down phase.

A. datagram switching

B. circuit switching

C. frame switching

D. none of the above

28)In which switching, there is no resource allocation for a packet.

A. datagram switching

B. circuit switching

C. frame switching

D. none of the above

29) Which network is a cross between a circuit switched and a datagram network. It has
characteristics of both.

A. virtual circuit
B. packet switched
C. frame switched
D. none of the above.

30) Packet - switched networks can also be divided into --------- categories

A. four
B. two
C. three
D. five

31) In ----------- there is no setup or teardown phase

 A. virtual switching
B. datagram switching
C. circuit switching
D. packet switching

32) A transmission media can have signal impairment because of

A. Noise
B. Attenuation
C. distortion
D. All of the above

33)The combination of two or more networks are called

A. Internetwork
B. WAN
C. MAN
D. LAN

34)Difficult reconnection and fault isolation are the disadvantages of

A. Star topology
B. Mesh topology
C. Ring topology
D. Bus topology

35)The term that refers to the structure and format of the data is

A. Syntax
B. Semantics
C. Standard
D. Agency

36) OSI stands for

A. Open Systems Interconnection

B. Online Systems Interconnection
C. Open Systems Internet
D. Online systems Interconnection
37) The parameter that refers to the set of rules that govern data communications are called

A. Forum
B. Standard
C. Agency
D. Protocol

38) Both station can transmit and receive data simultaneously in

A. simplex mode
B. Half duplex mode
C. Full duplex mode
D. None of Above

39) The parameter that refers to uneven delay of data packets in the delivery is

A. Jitter
B. Timelessness
C. Accuracy
D. Transmission medium

40) Performance, reliability and security are criteria of

A. Efficient network
B. intranet
C. Ethernet
D. None of Above

41) Telephone is an example of

A. Full Duplex
B. Simplex
C. Half Duplex
D. None of the above

42) The five components that make up a data communications system are the message, sender,
receiver, medium and

A. protocol
 B. Code
C. connecting device
D. both a and b

43) A Circuit-Switched Network is made of a set of switches connected by physical

A. links
B. media
C. nodes
D. lines

44) Setup, data transfer and connection teardown are three phases of

A. circuit switching
B. packet switching
C. message switching
D. None

45) The Asynchronous Transfer Mode (ATM) network is an example of

A. Packet switching network

B. Datagram Networks
C. Virtual circuit network
D. message switched network

46)A switch in a datagram network uses a routing table that is based on the

A. source addresses
B. port addresses
C. destination address
D. None

47)The identifier that is actually used for data transfer is called the

A. virtual-circuit identifier
B. global address
C. local address
D. header
48) A circuit-switched network is made of switches connected by physical links, in which each link is
divided into

A. n channels
B. n+1 channels
C. 2n channels
D. n-1 channels

49)The electromagnetic waves ranging in frequencies between 3 kHz and 1 GHz are called

A. High frequency
B. Infrared
C. Microwaves
D. radio waves

50)Guided media provides a conduit from one device to another, includes

A. twisted pair cable

B. fiber optic cable
C. coaxial cable
D. All of the above

51)Microwaves are used for

E. short-range communication
F. multicast communications
G. unicast communication
H. long range communication

52)The omnidirectional antennas send out signals in

A. one direction
B. 2 directions
C. no direction
D. all directions

53)The most common twisted-pair cable used in communications are

A. UTP
B. STP
C. normal twisted copper pair cables
D. None
54)The most common unshielded twisted pair connector is

A. RJ-45
B. RG-59
C. RG-58
D. RG-ll

55) In multimode propagation, the term step index refers to the

A. index of refraction
B. sudden change of signal
C. index of density
D. index of light rays

UNIT II

UNIT II DATA LINK LAYER

Services- Link-Layer Addressing - Framing- Noiseless Channels - Noisy channel protocols - HDLC-
CSMA/CD- CSMA/CA- IEEE 802.3- IEEE802.11- Bluetooth.

Multiple Choice Questions

1)The field of the MAC frame that alerts the receiver and enables it to synchronize is known as

A. SFD
B. preamble
C. source address
D. destination address

2) The maximum length of 1000BaseSX is

A. 550 m
B. 25 m
C. 100 m
D. 5000 m

3) 1000Base-LX has used two wires for long wave are

A. STP Cable
B. UTP Cable
 C. Fiber Optic
D. Coaxial Cable

4) The original Ethernet was created in

A. 1980
B. 1976
C. 1960
D. 1967

5) NIC stand for

A. Network Interface Card

B. National Internet code
C. Network Isolated card
D. Network international code

6) The term that is used to set standards to enable intercommunication among equipment from a
variety of manufacturers is called

A. Project 802
B. Project 8802
C. Project 2088
D. Project 208

7) The minimum frame length for 10-Mbps Ethernet is 64 bytes and the maximum is

A. 500 bytes
B. 1000 bytes
C. 1520 bytes
D. 1518 bytes

8) Fast Ethernet can transmit data at the rate of

A. 50 Mbps
B. 100 Mbps
C. 150 Mbps
D. 200 Mbps
9) CRC field is used in

A. HDLC
B. PPP
C. IEEE802.3
D. IEEE802.11

10) CRC field is found in

A. Error Correction
B. Sender address
C. receiver address
D. error detection information

11) A BSS without an AP is called an

A. ad-hoc network
B. infrastructure network
C. connectionless network
D. channelization network

12) Distributed Coordination Function (DCF) uses the mechanism of

A. CSMA/CD
B. CSMA/CA
C. TDMA
D. FDMA

13) Management frames, control frames and data frames are used by

A. Wireless LAN’s
B. Wireless MANs
C. Wireless WANs
D. None

14) In Bluetooth LAN, the devices are called

A. Nodes
B. Gadgets
 C. Piconet
D. Entity

15) The exact range of Bluetooth devices are

A. 10 m
B. 20 m
C. 30 m
D. 40 m

16) Each channel in Bluetooth layer is of

A. 1 MHz
B. 2 MHz
C. 3 MHz
D. 4 MHz

17)A Bluetooth LAN is an

A. Ad-hoc Network
B. infrastructure Signals
C. Ad-hoc signals
D. infrastructure LAN

18)The term in which a station can move from one basic service set to another is called

A. BSS transition mobility

B. ESS transition mobility
C. No transition mobility
D. none of the above

19) L2CAP have specific duty of

A. multiplexing
B. quality of service
C. segmentation and reassembly
D. All of the above

20)The Clear To Send frame in CSMA/CA handshake can prevent from

 A. Data overlap
B. Distort signals
C. Frames overlap
D. Collision

21)IEEE 802.11 Direct Sequence Spread Spectrum (DSSS) uses the data rate of

A. 1 and 2 Mbps
B. 6 to 54 Mbps
C. 5.5 and 11 Mbps
D. 2 and 54 Mbps

22) Bluetooth network consists of one primary device and up to

A. 5 Devices
B. 7 Devices
C. 9 Devices
D. 11 Devices

23) Carrier Sense Multiple Access (CSMA) is based on the medium called

A. Listen after talk

B. Listen before sending
C. Sense before transmit
D. Sense before Collision

24) A network using Carrier Sense Multiple Access/Collision Detection (CSMA/CD) has a
Bandwidth of

A. 2.5 Mbps
B. 5 Mbps
C. 7.5 Mbps
D. 10 Mbps

25) In CSMA/CA, An amount of time divided into slots is known as

A. Contention Procedure
B. Contention Window
C. Contention Signals
 D. Contention Energy

26) Random access is also called the

A. controlled access
B. channelization
C. authentication
D. contention methods

27) The time-out period is equal to the maximum possible propagation delay of

A. Square-trip
B. Round-trip
C. Rectangular-trip
D. Triangle-trip

28) The p-persistent method is used if the time slots with a slot duration equal to or greater than the
maximum of

A. Collision Time
B. Sense Time
C. Propagation Time
D. Navigation Time

29) Piggybacking protocol is a technique used for

A. ACKs
B. NAKs
C. both a and b
D. None

30) The frame type that refers to High-level Data Link Control error detection field is

A. Frame Check Sequence field

B. Control field
C. flag field
D. information field

31)In Asynchronous Balanced Mode (ABM)of HDLC, the link is

 A. unidirectional
B. bidirectional
C. point to point
D. multipoint

32)In byte stuffing, a special byte is added to the data section of the frame when there is a character
with the same pattern as the

A. flag
B. error
C. sender
D. destination

33)The term that refers to a set of procedures used to restrict the amount of data that the sender can
send before waiting for acknowledgment is

A. error control
B. flow control
C. delay
D. byte stuffing

34)The sequence numbers of the Stop-and-Wait Automatic Repeat Request are based on

A. simple arithmetic
B. modulo-2 arithmetic
C. logical arithmetic
D. modular multiplicative inverse

35)Stop-and-Wait Automatic Repeat Request is a special case of

A. Simplest Protocol
B. Go Back-N Automatic Repeat Request
C. Selective Repeat Automatic Repeat Request
D. Stop and Wait

36)Each frame in HDLC may contain up to

A. three fields
B. four fields
 C. five fields
D. six fields

37)In High-level Data Link Control (HDLC), the frame that is used only to transport control
information is called

A. I- frame
B. S-frame
C. V-frame
D. Piggybacking

38)Framing that is done on data link layer are of

A. 1 type
B. 2 types
C. 3 types
D. 4 types

39)Error control in the data link layer is based on

A. Automatic Repeat reQuest

B. manually repeat request
C. situation based
D. both a and b

40)The Stop and Wait Protocol uses the link of

A. modulation
B. full duplex
C. half duplex
D. none of the above

41)The send window in the Go-Back-N Protocol is an abstract concept defining an imaginary box
with

A. one variable
B. two variables
C. three variables
D. four variables
42)In which protocol, the size of the sender and receiver window must be at most one-half of 2^m in

A. Selective Repeat Automatic Repeat Request

B. Stop and Wait
C. Go Back-N Automatic Repeat Request
D. Simplest Protocol

43)The protocol that has no flow or error control is called

A. Simplest Protocol
B. Stop and Wait
C. Go Back-N Automatic Repeat Request
D. Selective Repeat Automatic Repeat Request

44) High-level Data Link Control is a

A. connectionless protocol
B. byte-oriented protocol
C. bit-oriented protocol
D. None

45) The Receive window in the Go-Back-N Protocol is an abstract concept defining an imaginary box
with

A. one variable
B. two variables
C. three variables
D. four variables

46) Preamble contains

A. 6 Bytes
B. 4 Bytes
C. 2 Bytes
D. 7 Bytes

47) In gigabit Ethernet three or more stations are connected by

A. Ring Topology
B. Bus Topology
C. Star Topology
D. Mesh Topology
48)Can Wireless LAN’s implement CSMA/CD

A. Yes
B. No
C. Both A and B
D. None of the above.

49)Mention the type of encoding used in the physical layer of Ethernet

A. Manchester
B. NRZ
C. RZ
D. 4B/5B encoding.

50) In Gigabit Ethernet, the maximum length of the cable is determined by the

A. Signal Attenuation
B. Distortion
C. Noise
D. Interference.