July, 2012
A9-R4: DATA COMMUNICATION AND NETWORKS TECHNOLOGIES
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. (1x10)
1.1 In TCP/IP, Packets may arrive out of sequence (they may have been routed differently, orone may have been dropped), so the ________ in each packets allow TCP to reassemble
the packets in the correct order and to request retransmission of any missing packets
A) Sequence numbers
B) Port numbers
C) Source_id number
D) Reassembling of the packets in the correct order is not permitted
1.2 UDP is a fast, unreliable protocol and unreliable means there is
A) No sequencing
B) No guaranteed delivery
C) No automatic retransmission of lost packets
D) All of the above
1.3 Two conductors separated by insulation such as TV 75 ohm cable refers to
A) Thinnet cable
B) Thicknet cable
C) Coaxial cable
D) Fiber optic cable
1.4 ________ is a client-server protocol used to monitor and manage networks remotely
A) SMTP
B) SNMP
C) TFTP
D) NFS
A9-R4 Page 2 of 6 July, 2012
1.5 GSM uses following Control channel
A) Broadcast Control Channel
B) Dedicated Control Channel
C) Common Control Channel
D) All the above
1.6 Present Cellular networks employ the following multiple access schemes namely
A) FDMA, TDMA and CDMA
B) TDMA and CDMA
C) FDMA and TDMA
D) FDMA and CDMA
1.7 Packet Switching
A) Does not require any advanced setup
B) Uses store and forward mechanism
C) Allows different packets to follow different paths depending on network conditions at the
time they are sent
D) All the above
1.8 ________ is the protocol used in Ethernet networks to ensure that only one network node is
transmitting on the network wire at any one time.
A) CSMA
B) CSMA/CD
C) CSMA/CA
D) IEEE 802.3
1.9 QPSK
A) can be used to double the data rate compared with a BPSK system while maintaining the
same bandwidth of the signal
B) can be used to Quadruple the data rate compared with a BPSK system while maintaining
the same bandwidth of the signal
C) can be used to double the data rate compared with a BPSK system while halving the
bandwidth needed
D) can be used to Quadruple the data rate compared with a BPSK system while doubling the
bandwidth needed
1.10 Dynamic Host Configuration Protocol (DHCP) is a network protocol that
A) automatically assign an IP address to a computer from a defined range of numbers
B) manually configures a computer to use a specific IP address
C) is used to translate protocol addresses to hardware interface addresses
D) is used to translate hardware interface addresses to protocol addresses
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. (1x10)
IPX/SPX.
2.2 Collisions cannot occur in Token Ring networks.
2.3 Each virtual circuit in an ATM network gets affected by traffic on other virtual circuits.
2.4 3G offers data rates of more than 144 Kbit/s, thereby opening the door to multimedia uses
such as video transmission, video-conferencing or high-speed internet access.
2.5 NFS is a system to share directories and files with others over a network.
2.6 In VOIP Analog voice data is encoded as digital data and the resulting voice data is inserted
into IP datagrams.
2.7 The twisting of the individual pairs in twisted pair increases electromagnetic interference.
2.8 FDDI is a ring based network.
2.9 Optical fiber consists of a column of glass or plastic surrounded by an opaque outer jacket.
2.10 HDLC, a point to point protocol, could be used as a data link layer protocol on a LAN.
3. Match words and phrases in column X with the closest related meaning/ word(s)/phrase(s) in column Y. Enter your selection in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1x10)
|
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X
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Y
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|||||
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3.1
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refers to the technique
of digitalizing an analog signal by sampling the magnitude of the signal at
uniform intervals and converting it into a series of digital or binary code
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A.
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Packet Switching
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||||
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3.2
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The open shortest path first (OSPF) protocol
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B.
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IPSec
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||||
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3.3
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Small packet size and a simple header structure
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C.
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259 Mbps
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||||
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3.4
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IP network-layer encryption.
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D.
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Gets and Puts
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||||
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3.5
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The OC-5 data rate.
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E.
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PCM
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||||
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3.6
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The
most commonly used telecom standard in Europe that uses the 900 MHz and 1800
MHz frequency bands.
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F.
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One 64Kbps
B-channels with two 16Kbps D channel
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||||
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3.7
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Basic Rate ISDN (BRI)
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G.
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link state routing method
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||||
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3.8
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Unused frequency known as.
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spaces
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between
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channels,
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H.
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Circuit Switching
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3.9
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SNMP
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I.
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56 Kbps
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||||
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3.10
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X.25 network
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J.
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GSM (Global System
Mobile communications)
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for
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|||
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|
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K
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Guard bands
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||||
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|
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L.
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Two 64Kbps
B-channels with one 16Kbps D channel
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||||
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|
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M.
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ATM
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||||
4. Each statement below has a blank space to fit one of the word(s) or phrase(s) in the list below. Enter your choice in the “tear-off” answer sheet attached to the question paper, following instructions therein. (1x10)
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A.
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Firewall
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B.
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Virtual Local Area
Networks (VLANs)
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C.
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CDMA (Code
Division Multiple Access)
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D.
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MAC
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E.
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Synchronous
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F.
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Cyclic Redundancy Check
|
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G.
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Router
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H.
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TCP
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I.
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IP
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J.
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FSK
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K.
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Two-pair
(four-wire)
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L.
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Synchronous
|
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M.
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UDP
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4.1 A ________ is a method of detecting errors in a block of data by performing a math
calculation on a stream of data.
4.2 ________ implements an access control policy.
4.3 ________ logically segment the physical LAN infrastructure into different subnets.
4.4 ________ uses a spread spectrum technique that allows a radio signal to be broadcast over
a large frequency range.
4.5 The ________ address is a 48-bit address expressed as 12 hexadecimal digits.
4.6 Actions that are measured against a time reference, or a clock signal, are referred to as
________ actions.
4.7 SONET/SDH are point-to-point blank networks ________.
4.8 A ________ interconnect two or more physically and logically separate network segments.
4.9 ________ is a technique that can be considered as a frequency modulated binary PCM.
4.10 The protocol used by DNS is ________.
PART TWO
(Answer any FOUR questions)
5.
a) What is digital Modulation? How is it different from Analog Modulation? Briefly differentiate
between ASK, FSK, PSK. In PSK clearly distinguish between BPSK and QPSK.
b) What is A virtual circuit? How is it different from a circuit in a circuit switched network Name
some network technologies that implement virtual circuits?
c) What are the differences between multiplexing and multiple access techniques? Discuss
three access techniques namely FDMA, TDMA and CDMA?
(5+5+5)
6.
a) Draw a Schematic diagram for fiber-optic communication system clearly showing
transmitter, receiver and signal repeaters (hint: include a detector, amplifier, and a signal
regenerator). Then explain the function of each component in detail. What are the reasons
by which fiber degrades the signal which type of modulation technique is used by Fiber-optic
telecommunication systems?
b) Explain HDLC protocol. On which layer does it work and explain how it reduces the chance
of errors.
c) What do you understand by terms physical topology and logical topology. Explain three
most popular LAN topologies namely Bus, Ring and Star. Discuss the merits and demerits of
each of these topologies.
(4+5+6)
7.
a) Explain Distance Vector and Link State routing protocols. See the Figure given below. If all
routers were running a Distance Vector protocol, explain why the path or 'route' chosen
would be from A to B directly over the ISDN serial link, even though that link is about 10
times slower than the indirect route from A C D B.
Also explain why a Link State protocol would choose the A C D B path? Which routing
protocol would be better to run in this example and why?
b) Differentiate between:
• FTP and TFTP
• SMTP and HTTP
c) Why Ad Hoc Networks are needed? What are Mobile Ad Hoc Networks (MANET)?
(5+6+4)
A9-R4 Page 6 of 6 July, 2012
8.
a) Give an overview of SSL/TLS protocol. What is the difference between an http and an https
connection when used for transferring data?
b) What is ALOHA? Discuss how Slotted ALOHA is different from Pure ALOHA.
c) Give the brief history of Ethernet. What is Carrier Sense Multiple Access with Collision
Detection (CSMA/CD) that Ethernet uses? Discuss IEEE 802.3 frame format explaining
each field.
(4+3+8)
9. Write Short notes on any three of the followings:
a) Digital Subscriber Line (DSL)
b) Transmission Control Protocol/Internet Protocol (TCP/IP) Suite
c) Very Small Aperture Terminal (VSAT)
d) Internet Protocol version 6 (IPv6)
e) Network Address Translation (NAT)
(3x5)
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