A9-R3: DATA COMMUNICATION & COMPUTER NETWORKS

January 2006 TOTAL TIME: 3 HOURS TOTAL MARKS: 100

(PART ONE-40; PART TWO – 60)

PART ONE (Answer all the questions)

1. Each question below gives a multiple choice of answers. Choose the most appropriate

one and enter in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

1.1 Which of the following are the smallest and largest possible values of an IP octet? A) 0 and 512 B) 255 and 512 C) 0 and 256 D) 0 and 255 1.2 The parameter Bit Error Rate (BER) plays more important role as compared to delay while

transmitting. A) Data B) Audio C) Video D) Compressed Video 1.3 Seamless networking refers to A) A complete end-to-end digital network. B) Use of a single platform for end-to-end communication where geographical distance between

communicating entities is hidden to the end user. C) Use of a single platform for end-to-end communication where geographical distance between

communication entities is visible to the end user. D) Use of a single platform to transmit data, audio and video. 1.4 In which of the following shape light pulses should be transmitted in order to cancel out

nearly all the dispersion effects. A) Cosine B) Triangular C) Hyperbolic Cosine D) Reciprocal of Hyperbolic Cosine 1.5 ARP is used to find A) IP address B) MAC address C) Subnet address D) Host address 1.6 Throughput of simple ALHOHA is A) 18%

B) 18.8% C) 36% D) 36.8% 1.7 If satellite is in geosynchronous orbit, it completes one orbit in A) One day (24 hours) B) One hour C) One month D) One year 1.8 Baud is A) Number of bits per second B) Number of signal changes per second C) Number of bytes per second D) Number of characters per second 1.9 Router operates in A) Data Link Layer B) Network Layer C) Transport Layer D) All of the above 1.10 In which ARQ, when a NAK is received, all frames sent since the last frame acknowledge are

retransmitted A) Stop-and-Wait B) Go back n C) Selective Reject D) Both A and B 2. Each statement below is either TRUE or FALSE. Choose the most appropriate one and

ENTER in the “tear-off” sheet attached to the question paper, following instructions therein. (1 x 10)

2.1 All WANs are necessarily packet switched networks.

2.2 Frame relay uses large variable sized packets in contrast to ATM.

2.3 ASK is a technique to convert digital data to an analog signal.

2.4 Executable files can be transmitted using SMTP.

2.5 Today’s Cellular networks employ all three multiple access schemes namely FDMA, TDMA and CDMA.

2.6 TCP uses a credit-based flow and error control technique that is somewhat different from the sliding-window flow control found in X.25 and HDLC.

2.7 Two computers cannot be connected via USB cable.

2.8 A bridged network allows communication between two computers on one segment to occur simultaneously as communication between two computers on another segment.

2.9 ADSL provides a lower bit rate downstream than upstream.

2.10 HTTP use port 80. 3. Match words and phrases in column X with the closest related meaning/

word(s)/phrases in column Y. Enter your selection in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

X Y

3.1 Connection Oriented WAN Technology A. Telnet

3.2 Circuit Switched B Channels and Packet Switched D Channel

B. HDLC

3.3 RF based physical layer C. CBR

3.4 Remote Login Protocol D. HTTP

3.5 Connectionless protocol E. Frame Relay

3.6 World Wide Web F. TCP

3.7 Real Time Service G. ISDN

3.8 Optical Transmission Systems H. UDP

3.9 Number of hexadecimal digits in Ethernet address

I. 8

3.10 Data Link layer J. ATM

K. ABR

L. FHSS

M. 12

N. WDM

4. Each statement below has blank space to fit one of the word(s) or phrases in the list

below. Enter your choice in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

A. CSMS/CD B. X.25 C. Distance vector

D. QAM E. Congestion control F. Token bus

G. ATM H. 48 Bytes I. PSK

J. Encryption K. CSMA/CA L. Masquerade

M. Routing N. Ethernet O. Line-state

P. 64 Bytes Q. Starting Delimiter R. SONET

4.1 IEEE 802.3 is popularly known as _________.

4.2 _________ is the network technology that can be used in both LAN and WAN.

4.3 The main characteristics of _________ are link-by-link flow control, sequence numbering and

error checking.

4.4 In order to ensure that collisions can be detected by all nodes on the Ethernet network, the

lower bound on Ethernet packet length is _________.

4.5 In order to share the transmission media wireless LANs use the _________ scheme.

4.6 _________ is the analog signaling technique used in ADSL and is a combination of

amplitude and phase modulation.

4.7 Optimality principle is used in _________.

4.8 A(n) _________ takes place when one entity pretends to be different entity.

4.9 The first field in a Token Ring frame is called _________.

4.10 Routing protocols based on _________ does not exchange their routing tables periodically.

PART TWO (Answer any FOUR questions)

5. a) Write in brief the features of the following transmission media: i) Coaxial Cable ii) Fiber Optic Cable b) Find out the capacity of a telephone line that transmits frequencies from 300 Hz and 3400 Hz

with a signal to noise ratio of 35dB. c) What is pulse code modulation? What is the equivalent bit rate of a PCM channel having

bandwidth of 4 KHz?

(8+3+4) 6. a) What is the difference between: - i) datagram subnet and virtual-circuit subnet. ii) circuit switching and packet switching. b) What advantages does TCP have over UDP? What are the features, which make TCP a

reliable protocol? c) Explain the function of: Repeater, Bridge and Gateways.

(8+[2+2]+3) 7. a) Explain the operation of CRC error detection method. By means of an example show how: i) The error detection bits are generated ii) The received frame is checked for transmission errors Use the generator polynomial x5 + x4 + x2 + x + 1 b) What is static routing? How does it differ from dynamic routing? c) Discuss the problem of count to infinity associated with distance vector routing technique.

(8+4+3) 8. a) What are the reasons for congestion in a network? Describe any one method for congestion

control. b) Could HDLC be used as a data link protocol for a LAN? Explain your answer. c) Describe the advantages of a small cell size in ATM.

(7+4+4) 9. Write short notes on any three: a) SNMP b) VPN c) Firewall d) GSM

July 2003 TOTAL TIME: 3 HOURS TOTAL MARKS: 100

(PART ONE-40; PART TWO – 60)

PART ONE (Answer all the questions)

1. Each question below gives a multiple choice of answers. Choose the most appropriate

one and enter in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

1.1 Learning about the neighbours through special HELLO packets is the first step in

A) distance vector routing B) local area routing C) link state routing D) none of the above

1.2 Sliding windows is a technique for

A) line discipline B) error control C) flow control D) session management

1.3 In TCP, the path A) upto destination is allocated before the transmission of message begins B) upto next intermediate node is allocated before the transmission of message begins C) to be followed depends on the length of message D) none of the above

1.4 A bridge recognizes addresses of

A) layer 1 B) layer 2 C) layer 3 D) all of the above

1.5 Mapping from MAC address to IP address is done by A) SNMP B) ARP C) RARP D) SMTP

1.6 To interconnect two homogeneous WANs, we need a

A) bridge B) router C) repeater D) none of the above

1.7 To employ multi-access in GSM, users are given different

A) time slots B) bandpass filters C) handsets D) none of the above

1.8 Base Station and MSC are related to

A) cellular radio B) ISO-OSI model C) ARPANET structure D) none of the above

1.9 DNS name space in the Internet is

A) flat and centralized B) hierarchical and centralized C) flat and distributed D) hierarchical and distributed

1.10 Usually security in a network is achieved by

A) layering B) grade of service C) addressing D) cryptography

2. Each statement below is either TRUE or FALSE. Choose the most appropriate one and

ENTER in the “tear-off” sheet attached to the question paper, following instructions therein. (1 x 10)

2.1 Dial-up is always better than leased line.

2.2 Synchronous data link control (SDLC) protocol has more control overhead than asynchronous data link control (ADCL) protocol.

2.3 In IEEE 802.11b LAN, wireless technology is used.

2.4 DPSK with four phases will enable the bit rate to be tripled over the corresponding two phase modulation.

2.5 In VLANs, the bust can be used as a common broadcast medium.

2.6 MIB is used in SMTP.

2.7 IP is a best-effort connectionless protocol.

2.8 Medium access protocols are associated with layer 2.

2.9 Switching HUBs are less efficient than simple HUBs.

2.10 CRC is also used in TCP. 3. Match words and phrases in column X with the closest related meaning/

word(s)/phrases in column Y. Enter your selection in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

X Y

3.1 Cell switching A. IPv6

3.2 Coaxial cable B. UDP

3.3 Secure wireless multiplexing C. FTP

3.4 128 bit address space D. Cryptography

3.5 Converting plain text to cipher text and vice versa E. GSM

3.6 900/1800 MHz F. Cable TV

3.7 Downloading files G. 10 Hz

3.8 LAN architecture from IBM H. Star topology

3.9 2B+D I. ISDN

3.10 Transport layer of INTERNET J. Token Ring

K. FDM

L. CDMA

M. CODEC

N. MODEM

O. ATM

4. Each statement below has blank space to fit one of the word(s) or phrases in the list

below. Enter your choice in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

A. TFTP B. Message C. VPN

D. Telnet E. BSC F. PPP

G. Fast LAN H. Packet I. HTTP

J. Character stuffing K. IP address L. Two

M. Bit stuffing N. MAC address O. Quantization

P. Resistance Q. Three R. Sampling

4.1 To implement a _____ over the INTERNET, tunneling is used.

4.2 _____ is the most common protocol used over dial-up lines to access the INTERNET.

4.3 The protocol used to transfer HTML pages is called _____.

4.4 In remote login, _____ is used to access distant servers.

4.5 The INTERNET is a _____ switched network.

4.6 In the INTERNET, _____ is used to forward data packets in intermediate routers.

4.7 The bottom _____ layers to TCP/IP suite are non-standard.

4.8 _____ is the first step in digitizing an analog signal.

4.9 The main advantage of PCM system is its _____ to system noise, offered by digital signals.

4.10 In Bisync protocol, _____ is used to avoid improper termination of frames.

PART - TWO (Answer ANY FOUR questions)

5. a) What is the difference between flow control and congestion control? b) What is reflection? What happens to a beam of light as it travels to a less sense medium?

What happens if it travels to a denser medium? c) How does ionospheric propagation work? Which types of users normally use this type of

propagation? d) What is the difference between network layer delivery and transport layer delivery?

(2+[1+1+2]+4+5) 6. a) Compare virtual circuit with datagram subnet? b) How is one TDM signal separated into its original components? Consider both

implementations of TDM? c) What procedure is used to prevent a stream of binary data from being misinterpreted as an

HDLC flag? Explain ht operation of this procedure? (5+7+3)

7. a) Compare fibre optic cable with UTP cable when used as transmission media in LANs. b) Why is IP not exactly suitable for real time services? c) Compare and contrast CSMA/CD and token-passing access methods. d) What is a subnet mask and why is it necessary?

(3+3+4+[2+3]) 8. a) What are the different classes of addresses used in Ipv4? List their ranges in dotted decimal

notation. b) What are the roles of repeaters, bridges, routers and gateways in achieving internetworking?

Identify the layers in which they operate. c) Computing the checksum for the following data frame, find the complete transmitted frame

bit pattern: data, D = 11001011011 generator polynomial, G(x) = x4 + x + 1

d) ([2+4]+[4+2+3)

9. Write short notes on any three: i) VSAT ii) QPSK iii) SONET iv) Spread Spectrum

(3x5)

A9-R3: DATA COMMUNICATION & COMPUTER NETWORKS

NOTE:

1. There are TWO PARTS in this Module/paper. PART ONE contains FOUR questions and PART TWO contains FOUR questions.

2. PART ONE is to be answered in the TEAR-OFFANSWER SHEET only, attached to the

question paper, as per the instructions contained therein. PART ONE is NOT to be answered in the answer book.

3. Maximum time allotted for PART ONE is ONE HOUR. Answer book for PART TWO will be

supplied at the table when the answer sheet for PART ONE is returned. However, candidates who complete PART ONE earlier than one hour, can collect the answer book for PART TWO immediately after handing over the answer sheet for PART ONE.

TOTAL TIME: 3 HOURS TOTAL MARKS: 100 (PART ONE-40; PART TWO – 60)

PART ONE

(Answer all the questions) 1. Each question below gives a multiple choice of answers. Choose the most appropriate

one and enter in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

1.1 One factor in the accuracy of a reconstructed PCM signal is the A) Signal bandwidth B) Carrier frequency C) Number of bits used for quantization. D) Baud rate 1.2 Category 1 UTP cable is most often used in A) Fast Ethernet Networks B) Traditional Ethernet Networks C) Infrared Networks D) Telephone Networks 1.3 In 16-QAM, there are 16 A) Combinations of phase and amplitude B) Amplitudes C) Phases D) bps 1.4 Guard bands increase the bandwidth for A) FDM B) TDM C) CDM D) None of the above 1.5 The physical connection between an end point and a switch or between two switches is A) Transmission path B) Virtual path C) Virtual circuit D) None of the above

1.6 Which of the following is an application layer service? A) Remote log-in B) File transfer and access C) Mail service D) All of the above 1.7 The main function of transport layer is A) Node-to-node delivery B) Process-to-process delivery C) Synchronization D) Updating and maintenance of routing tables 1.8 In which type of switching do all the packets of a message follow the same channels of a

path? A) Data gram packet switching B) Virtual switching packet switching C) Message switching D) None of the above 1.9 The shortest frame in HDLC protocol is usually the A) Information frame B) Supervisory frame C) Management frame D) None of the above 1.10 The device operating at Data link layer is A) Bridge B) Router C) Repeater D) None of the above

2. Each statement below is either TRUE or FALSE. Choose the most appropriate one and ENTER in the “tear-off” sheet attached to the question paper, following instructions therein. (1 x 10)

2.1 In FDM the users take turns in a round robin, each one periodically getting the entire bandwidth for a little burst of time.

2.2 The minimum bandwidth required for QAM transmission is the same as that required for ASK and PSK transmission.

2.3 Fiber-optic cable is used in backbone networks, cable TV networks and fast Ethernet networks.

2.4 A multipoint connection provides a dedicated link between two devices.

2.5 Routing is a function of data link layer.

2.6 Flow control is needed to prevent collision between sender and receiver.

2.7 HDLC is an actual protocol designed to support both half-duplex and full duplex communication over point-to-point and multipoint links.

2.8 UDP and TCP are both network layer protocols.

2.9 An ARP request is broadcast to all devices on the network.

2.10 Routing and switching in frame relay are performed by the data link layer. 3. Match words and phrases in column X with the closest related meaning/

word(s)/phrases in column Y. Enter your selection in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

X Y

3.1 It is the function of network layer. A. MAC

3.2 It is the connectionless protocol in Transport layer. B. ARP

3.3 It is the internetworking protocol suite. C. DNS

3.4 This sublayer is responsible for the operation of the CSMS/CD access method.

D. Bridge

3.5 The protocol maps an IP address to a MAC address. E. Frame Relay

3.6 It is a client-server application that identifies each host on the Internet with a unique user-friendly name.

F. Congestion control

3.7 It connects two LAN segments at Data Link layer. G. TDM

3.8 It is a virtual circuit WAN that was designed to respond to allow bursty data and a frame size of 9000 bytes.

H. TCP

3.9 It is a second-generation cellular phone system. I. MODEM

3.10 It is known as simultaneous transmission of multiple signals across a single data link.

J. UDP

K. Satellite

L. TCP/IP

M. Gateway

N. GSM

O. RARP

4. Each statement below has blank space to fit one of the word(s) or phrases in the list below. Enter your choice in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

A. Network B. Increases C. WDM

D. Circuit E. Presentation F. Packet

G. TCP H. ICMP I. CRC

J. Remains the same K. TDM L. UDP

M. Data Link N. Physical O. Decreases

P. Token Bus Q. CSMA/CD R. SNMP

4.1 The _________ layer changes bits into electromagnetic signals.

4.2 As the bit rate of an FSK signal increases, the bandwidth __________.

4.3 __________ is similar in concept to FDM. The signals being multiplexed, however, are light waves.

4.4 __________ is a powerful redundancy checking technique, which appends a sequence of redundant bits derived from binary division to the data unit.

4.5 In __________ protocol, a station must listen to a medium prior to sending data onto the line.

4.6 __________ layer provides services to transport layer.

4.7 The main Internet transport protocol is __________.

4.8 __________ switching statically reserves the required bandwidth in advance.

4.9 __________ LAN supports priorities and can be configured to provide a guaranteed fraction of the bandwidth to high-priority traffic.

4.10 The operation of the Internet is monitored closely by the routers. When something unexpected occurs, the event is reported by the __________.

PART TWO (Answer Any Four questions)

5. a) What is the transmission rate on Ethernet LANs? For a given transmission rate, can each

user on the LAN continuously transmit at the rate? b) What are some of the physical media that Ethernet can run over? c) What advantage does a circuit-switched network have over a packet-switched network?

What advantages does TDM have over FDM in a circuit-switched network? (5+5+5)

6. a) List two ways in which the OSI reference model and the TCP/IP reference model are the

same. Now, list the two ways in which they differ. b) What is the principle difference between connectionless communication and connection-

oriented communication? c) Why would the token-ring protocol be inefficient if the LAN has a very large perimeter?

(6+6+3) 7. a) What is the main difference between TCP and UDP? b) Give an advantage and disadvantage of frame relay over a leased telephone line. c) What are the two main functions of a datagram based network layer? What additional

functions does a VC-based network layer have? (3+6+6)

8. a) Compare and contrast link-state and distance-vector routing algorithms. b) Each Internet host will have at least one local name serve and one authoritative name

server. What role does each of these servers have in DNS? c) What is an important difference between a Symmetric key system and a Public key system?

(5+5+5) 9. Write short notes on any three of the following: i) X.25 ii) HDLC

iii) DNS iv) SNMP

(3x5)

A9-R3: DATA COMMUNICATION & COMPUTER NETWORKS

NOTE:

1. There are TWO PARTS in this Module/paper. PART ONE contains FOUR questions and PART TWO contains FOUR questions.

2. PART ONE is to be answered in the TEAR-OFFANSWER SHEET only, attached to the

question paper, as per the instructions contained therein. PART ONE is NOT to be answered in the answer book.

3. Maximum time allotted for PART ONE is ONE HOUR. Answer book for PART TWO will be

supplied at the table when the answer sheet for PART ONE is returned. However, candidates who complete PART ONE earlier than one hour, can collect the answer book for PART TWO immediately after handing over the answer sheet for PART ONE.

TOTAL TIME: 3 HOURS TOTAL MARKS: 100 (PART ONE-40; PART TWO – 60)

PART ONE

(Answer all the questions) 1. Each question below gives a multiple choice of answers. Choose the most appropriate

one and enter in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

1.1 Learning about the neighbours through special HELLO packets is the first step in

A) distance vector routing B) local area routing C) link state routing D) none of the above

1.2 Sliding windows is a technique for

A) line discipline B) error control C) flow control D) session management

1.3 In TCP, the path A) upto destination is allocated before the transmission of message begins B) upto next intermediate node is allocated before the transmission of message begins C) to be followed depends on the length of message D) none of the above

1.4 A bridge recognizes addresses of

A) layer 1 B) layer 2 C) layer 3 D) all of the above

1.5 Mapping from MAC address to IP address is done by A) SNMP B) ARP C) RARP D) SMTP

1.6 To interconnect two homogeneous WANs, we need a A) bridge B) router C) repeater D) none of the above

1.7 To employ multi-access in GSM, users are given different

A) time slots B) bandpass filters C) handsets D) none of the above

1.8 Base Station and MSC are related to

A) cellular radio B) ISO-OSI model C) ARPANET structure D) none of the above

1.9 DNS name space in the Internet is

A) flat and centralized B) hierarchical and centralized C) flat and distributed D) hierarchical and distributed

1.10 Usually security in a network is achieved by

A) layering B) grade of service C) addressing D) cryptography

2. Each statement below is either TRUE or FALSE. Choose the most appropriate one and ENTER in the “tear-off” sheet attached to the question paper, following instructions therein. (1 x 10)

2.1 Dial-up is always better than leased line.

2.2 Synchronous data link control (SDLC) protocol has more control overhead than asynchronous data link control (ADCL) protocol.

2.3 In IEEE 802.11b LAN, wireless technology is used.

2.4 DPSK with four phases will enable the bit rate to be tripled over the corresponding two phase modulation.

2.5 In VLANs, the bust can be used as a common broadcast medium.

2.6 MIB is used in SMTP.

2.7 IP is a best-effort connectionless protocol.

2.8 Medium access protocols are associated with layer 2.

2.9 Switching HUBs are less efficient than simple HUBs.

2.10 CRC is also used in TCP. 3. Match words and phrases in column X with the closest related meaning/

word(s)/phrases in column Y. Enter your selection in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

X Y

3.1 Cell switching A. IPv6

3.2 Coaxial cable B. UDP

3.3 Secure wireless multiplexing C. FTP

3.4 128 bit address space D. Cryptography

3.5 Converting plain text to cipher text and vice versa E. GSM

3.6 900/1800 MHz F. Cable TV

3.7 Downloading files G. 10 Hz

3.8 LAN architecture from IBM H. Star topology

3.9 2B+D I. ISDN

3.10 Transport layer of INTERNET J. Token Ring

K. FDM

L. CDMA

M. CODEC

N. MODEM

O. ATM

4. Each statement below has blank space to fit one of the word(s) or phrases in the list below. Enter your choice in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

A. TFTP B. Message C. VPN

D. Telnet E. BSC F. PPP

G. Fast LAN H. Packet I. HTTP

J. Character stuffing K. IP address L. Two

M. Bit stuffing N. MAC address O. Quantization

P. Resistance Q. Three R. Sampling

4.1 To implement a _____ over the INTERNET, tunneling is used.

4.2 _____ is the most common protocol used over dial-up lines to access the INTERNET.

4.3 The protocol used to transfer HTML pages is called _____.

4.4 In remote login, _____ is used to access distant servers.

4.5 The INTERNET is a _____ switched network.

4.6 In the INTERNET, _____ is used to forward data packets in intermediate routers.

4.7 The bottom _____ layers to TCP/IP suite are non-standard.

4.8 _____ is the first step in digitizing an analog signal.

4.9 The main advantage of PCM system is its _____ to system noise, offered by digital signals.

4.10 In Bisync protocol, _____ is used to avoid improper termination of frames.

PART - TWO (Answer ANY FOUR questions)

5. a) What is the difference between flow control and congestion control? b) What is reflection? What happens to a beam of light as it travels to a less sense medium?

What happens if it travels to a denser medium? c) How does ionospheric propagation work? Which types of users normally use this type of

propagation? d) What is the difference between network layer delivery and transport layer delivery?

(2+[1+1+2]+4+5) 6. a) Compare virtual circuit with datagram subnet? b) How is one TDM signal separated into its original components? Consider both

implementations of TDM? c) What procedure is used to prevent a stream of binary data from being misinterpreted as an

HDLC flag? Explain ht operation of this procedure? (5+7+3)

7. a) Compare fibre optic cable with UTP cable when used as transmission media in LANs. b) Why is IP not exactly suitable for real time services? c) Compare and contrast CSMA/CD and token-passing access methods. d) What is a subnet mask and why is it necessary?

(3+3+4+[2+3]) 8. a) What are the different classes of addresses used in Ipv4? List their ranges in dotted decimal

notation. b) What are the roles of repeaters, bridges, routers and gateways in achieving internetworking?

Identify the layers in which they operate. c) Computing the checksum for the following data frame, find the complete transmitted frame

bit pattern: data, D = 11001011011 generator polynomial, G(x) = x4 + x + 1 d)

([2+4]+[4+2+3) 9. Write short notes on any three: i) VSAT ii) QPSK iii) SONET iv) Spread Spectrum

(3x5)

A9-R3: DATA COMMUNICATION & COMPUTER NETWORKS

NOTE:

1. There are TWO PARTS in this Module/paper. PART ONE contains FOUR questions and PART TWO contains FOUR questions.

2. PART ONE is to be answered in the TEAR-OFFANSWER SHEET only, attached to

the question paper, as per the instructions contained therein. PART ONE is NOT to be answered in the answer book.

3. Maximum time allotted for PART ONE is ONE HOUR. Answer book for PART TWO

will be supplied at the table when the answer sheet for PART ONE is returned. However, candidates who complete PART ONE earlier than one hour, can collect the answer book for PART TWO immediately after handing over the answer sheet for PART ONE.

TOTAL TIME: 3 HOURS TOTAL MARKS: 100

(PART ONE-40; PART TWO – 60)

PART ONE

(Answer all the questions) 1. Each question below gives a multiple choice of answers. Choose the most

appropriate one and enter in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

1.1 One factor in the accuracy of a reconstructed PCM signal is the A) Signal bandwidth B) Carrier frequency C) Number of bits used for quantization. D) Baud rate 1.2 Category 1 UTP cable is most often used in A) Fast Ethernet Networks B) Traditional Ethernet Networks C) Infrared Networks D) Telephone Networks 1.3 In 16-QAM, there are 16 A) Combinations of phase and amplitude B) Amplitudes C) Phases D) bps 1.4 Guard bands increase the bandwidth for A) FDM B) TDM C) CDM D) None of the above

1.5 The physical connection between an end point and a switch or between two switches is

A) Transmission path B) Virtual path C) Virtual circuit D) None of the above 1.6 Which of the following is an application layer service? A) Remote log-in B) File transfer and access C) Mail service D) All of the above 1.7 The main function of transport layer is A) Node-to-node delivery B) Process-to-process delivery C) Synchronization D) Updating and maintenance of routing tables 1.8 In which type of switching do all the packets of a message follow the same channels

of a path? A) Data gram packet switching B) Virtual switching packet switching C) Message switching D) None of the above 1.9 The shortest frame in HDLC protocol is usually the A) Information frame B) Supervisory frame C) Management frame D) None of the above 1.10 The device operating at Data link layer is A) Bridge B) Router C) Repeater D) None of the above

2. Each statement below is either TRUE or FALSE. Choose the most appropriate

one and ENTER in the “tear-off” sheet attached to the question paper, following instructions therein. (1 x 10)

2.1 In FDM the users take turns in a round robin, each one periodically getting the entire bandwidth for a little burst of time.

2.2 The minimum bandwidth required for QAM transmission is the same as that required for ASK and PSK transmission.

2.3 Fiber-optic cable is used in backbone networks, cable TV networks and fast Ethernet networks.

2.4 A multipoint connection provides a dedicated link between two devices.

2.5 Routing is a function of data link layer.

2.6 Flow control is needed to prevent collision between sender and receiver.

2.7 HDLC is an actual protocol designed to support both half-duplex and full duplex communication over point-to-point and multipoint links.

2.8 UDP and TCP are both network layer protocols.

2.9 An ARP request is broadcast to all devices on the network.

2.10 Routing and switching in frame relay are performed by the data link layer. 3. Match words and phrases in column X with the closest related meaning/

word(s)/phrases in column Y. Enter your selection in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

X Y

3.1 It is the function of network layer. A. MAC

3.2 It is the connectionless protocol in Transport layer. B. ARP

3.3 It is the internetworking protocol suite. C. DNS

3.4 This sublayer is responsible for the operation of the CSMS/CD access method.

D. Bridge

3.5 The protocol maps an IP address to a MAC address. E. Frame Relay

3.6 It is a client-server application that identifies each host on the Internet with a unique user-friendly name.

F. Congestion control

3.7 It connects two LAN segments at Data Link layer. G. TDM

3.8 It is a virtual circuit WAN that was designed to respond to allow bursty data and a frame size of 9000 bytes.

H. TCP

3.9 It is a second-generation cellular phone system. I. MODEM

3.10 It is known as simultaneous transmission of multiple signals across a single data link.

J. UDP

K. Satellite

L. TCP/IP

M. Gateway

N. GSM

O. RARP

4. Each statement below has blank space to fit one of the word(s) or phrases in

the list below. Enter your choice in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1 x 10)

A. Network B. Increases C. WDM

D. Circuit E. Presentation F. Packet

G. TCP H. ICMP I. CRC

J. Remains the same K. TDM L. UDP

M. Data Link N. Physical O. Decreases

P. Token Bus Q. CSMA/CD R. SNMP

4.1 The _________ layer changes bits into electromagnetic signals.

4.2 As the bit rate of an FSK signal increases, the bandwidth __________.

4.3 __________ is similar in concept to FDM. The signals being multiplexed, however, are light waves.

4.4 __________ is a powerful redundancy checking technique, which appends a sequence of redundant bits derived from binary division to the data unit.

4.5 In __________ protocol, a station must listen to a medium prior to sending data onto the line.

4.6 __________ layer provides services to transport layer.

4.7 The main Internet transport protocol is __________.

4.8 __________ switching statically reserves the required bandwidth in advance.

4.9 __________ LAN supports priorities and can be configured to provide a guaranteed fraction of the bandwidth to high-priority traffic.

4.10 The operation of the Internet is monitored closely by the routers. When something unexpected occurs, the event is reported by the __________.

PART TWO (Answer Any Four questions)

5. a) What is the transmission rate on Ethernet LANs? For a given transmission rate, can

each user on the LAN continuously transmit at the rate? b) What are some of the physical media that Ethernet can run over? c) What advantage does a circuit-switched network have over a packet-switched

network? What advantages does TDM have over FDM in a circuit-switched network? (5+5+5)

6. a) List two ways in which the OSI reference model and the TCP/IP reference model are

the same. Now, list the two ways in which they differ. b) What is the principle difference between connectionless communication and

connection-oriented communication? c) Why would the token-ring protocol be inefficient if the LAN has a very large

perimeter? (6+6+3)

7. a) What is the main difference between TCP and UDP? b) Give an advantage and disadvantage of frame relay over a leased telephone line. c) What are the two main functions of a datagram based network layer? What additional

functions does a VC-based network layer have?

(3+6+6) 8. a) Compare and contrast link-state and distance-vector routing algorithms. b) Each Internet host will have at least one local name serve and one authoritative

name server. What role does each of these servers have in DNS? c) What is an important difference between a Symmetric key system and a Public key

system? (5+5+5)

9. Write short notes on any three of the following: i) X.25 ii) HDLC

iv) DNS iv) SNMP

(3x5)