Assignment 1 Semester 2

Assignment 01: Semester 2


Computer Networks

COS2626

Semester 2

School of Computing

IMPORTANT INFORMATION:

This tutorial letter contains Assignment 01 for Semester 2

2


Assignment 01 Semester 2

Due Date 22nd August 2014

Unique Assignment number 759552

Study Material Chapters 2 - 7

Submission Procedure Mark-reading sheet or electronically via myUNISA

Number of Questions 55

Assignment Weight 40%

WARNING: IF YOU DO NOT SUBMIT THIS ASSIGNMENT YOU WILL NOT BE ALLOWED EXAMINATION ADMISSION!

Question 1

Standards define the __ __ performance of a product or service.

1. ideal

2. most acceptable

3. minimum acceptable

4. maximum acceptable

Question 2

Study the following list of characteristics:

Specialized United Nations agency Regulates international telecommunications Provides developing countries with technical expertise and equipment Founded in 1865; joined United Nations in 1947 Members from 193 countries Focus

Global telecommunications issues

Worldwide Internet services implementation

These characteristics describe the organizations standards.

1. EIA (Electronic Industries Alliance)

2. IEEE (Institute of Electrical and Electronics Engineers)

3. ITU (International Telecommunication Union)

4. ISO (International Organization for Standardization)


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Question 3

The following diagram illustrates layer protocols managing voice

communications.

1. Presentation

2. Application

3. Transport

4. Session

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Question 4

Which statement(s) regarding checksums is (are) FALSE?

a. To ensure data integrity further, connectionless protocols such as TCP (Transmission

Control Protocol) use a checksum.

b. A checksum is a unique character string that allows the receiving node to determine if an

arriving data unit exactly matches the data unit sent by the source.

c. Checksums are added to data at the source and verified at the destination. If at the

source, a checksum does not match what the destination predicted, the destinations

Transport layer protocols ask the source to retransmit the data.

1. only b

2. only b and c

3. only a and c

4. a, b and c

Question 5

A takes the values of all of the preceding fields in the frame and generates a unique

4-byte number, the .

1. CRC (Cyclic Redundancy Check); FCS (Frame Check Sequence)

2. FCS; CRC

3. Checksum; CRS

4. FCS; checksum

Question 6

Significant IEEE (Institute of Electrical and Electronics Engineers) 802 standards are ,

which describes Ethernet; 802.11 which describe , and which describes

broadband wireless metropolitan networks.

1. 802.3; Wireless Networks; 802.16

2. 802.5; Wireless personal area networks; 802.15

3. 802.2; Mobile broadband wireless networks; 802.20

4. 802.1; WRANs (Wireless Regional Area Networks); 802.22


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Question 7

Study the following diagram of a typical analog signal. C denotes the waves _________ and is

________________________.

1. amplitude; a measure of its strength at any given point

2. wavelength; the distance between corresponding points on a waves cycle

3. phase; the progress of a wave over time in relationship to a fixed point

4. voltage; the strength of the signal

Question 8

Which one of the following decimal numbers corresponds to the binary number 00001001?

1. 3

2. 5

3. 7

4. 9

Question 9

Which one of the following statements regarding simplex, half-duplex and duplex transmission

is TRUE?

1. When signals are free to travel in both directions over a medium simultaneously, the

transmission is considered duplex.

2. A football coach calling out orders to his team through a megaphone is using half-duplex

communication.

3. An apartment's intercom system that requires you to press a "talk" button in order to allow

your voice to be transmitted over the wire uses duplex communication.

4. Modern NICs (Network Interface Cards) use half-duplex by default.

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Question 10

_ ___ is a technology used with fiber-optic cable that enables one fiber-optic connection

to carry multiple light signals simultaneously.

1. Statistical multiplexing

2. WDM (Wavelength Division Multiplexing)

3. TDM (Time Division Multiplexing)

4. FDM (Frequency Division Multiplexing)

Question 11

Which of the following TWO statements regarding bandwidth and throughput are TRUE?

a. Bandwidth, expressed in kilobits, is a measure of the difference between the highest and

lowest frequencies that a medium can transmit.

b. Throughput is the measure of how much data is transmitted during a given period of time.

c. Bandwidth and throughput are inversely proportional.

d. Throughput is commonly expressed as a quantity of bits transmitted per second.

1. a and b

2. b and c

3. c and d

4. b and d

Question 12

Study the following diagram.

1. This diagram illustrates how a digital signal is distorted by noise and then repeated.

2. This diagram illustrates how an analog signal is distorted by noise and then repeated.

3. This diagram illustrates how a digital signal is distorted by noise and then amplified.

4. This diagram illustrates how an analog signal is distorted by noise and then amplified.


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Question 13

The most significant factor in choosing a transmission method is its ____.

1. noise

2. attenuation

3. throughput

4. latency

Question 14

In the figure depicted above, which letter represents the insulation?

1. A

2. B

3. C

4. D

Question 15

Study the following diagram representing a connector. Which one of the following statements

regarding this diagram is CORRECT?

1. The diagram represents a RJ-11 (Registered Jack 11) modular connector.

2. The diagram represents a MT-RJ (Mechanical Transfer Registered Jack) modular

connector.

3. The diagram represents a SC (Subscriber Connector).

4. The diagram represents a RJ-45 (Registered Jack 45) modular connector.

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Question 16

Study the following characteristic's of fiber-optic cables:

a. Throughput - Fiber has proved reliable in transmitting data at rates that reach 100 gigabits

(or 100,000 megabits) per second per channel.

b. Cost - Fiber-optic cable is the most expensive transmission medium. Because of its cost,

most organizations find it impractical to run fiber to every desktop.

c. Connector - With fiber cabling, you can use any of two different types of connectors

including RJ-45 and RJ-11.

d. Noise immunity - Because fiber does not conduct electrical current to transmit signals, it is

unaffected by EMI (Electromagnetic Interference).

e. Size and scalability - Depending on the type of fiber-optic cable used, segment lengths

vary from 150 to 40,000 meters.

Which of the above is (are) NOT characteristics of fiber-optic cables?

1. a, d and e

2. only c

3. b and e

4. b, c and e

Question 17

What type of connectors do 'A' and 'B' in the following diagram respectively represent?

1. RJ-45; RJ-11

2. ST (Straight Tip); SC

3. LC (Local Connector); MT-RJ

4. DB-25; DB-9


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Question 18

What is the first point of interconnection between an organizations LAN (Local Area Network) or

WAN (Wide Area Network) and a service providers facility?

1. MDF (Main Distribution Frame)

2. Entrance facilities

3. Cross-connect facilities

4. Work area

Question 19

Which one of the following statements regarding the TCP/IP (Transmission Control

Protocol/Internet Protocol) as compared to the OSI (Open Systems Interconnection) model is

not TRUE?

1. The Application layer of the TCP/IP model is roughly equivalent to the Application,

Presentation and Session layers of the OSI model.

2. The Transport layer of the TCP/IP model is roughly equivalent to the Transport layer of the

OSI model.

3. The Internet layer is equivalent to the Network layer of the OSI model.

4. The Data Interface layer is roughly equivalent to the Data Link and Physical layers of the

OSI model.

Question 20

TCP ensures data delivery through and .

1. sequencing; segmentation

2. segmentation; reassembly

3. sequencing; checksums

4. checksums; reassembly

Question 21

Identify the following TCP segment fields:

a. Identifies the data segment's position in the stream of data segments already sent.

b. Confirms receipt of the data via a return message to the sender.

c. Indicates how many bytes the sender can issue to a receiver while acknowledgement for

this segment is outstanding.

d. Contains filler information to ensure that the size of the TCP header is a multiple of 32 bits.

1. Checksum; Reply; Urgent pointer; Data

2. Sequence number; Acknowledgment number (ACK); Sliding-window size (or window);

Padding

3. Total length; Receipt; Identification; Checksum

4. Position; Return; Waiting; Insert

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Question 22

Which statement (s) regarding UDP (User Datagram Protocol) is (are) TRUE?

a. UDP belongs to the Transport layer of the TCP/IP and OSI models.

b. UDP provides no error checking or sequencing.

c. The UDP header contains only four fields: Source Port, Destination port, Sequence

number and Acknowledgement number (ACK)

1. only a

2. only b and c

3. only a and b

4. only c

Question 23

Which statement (s) regarding the fields in IPv4 is (are) INCORRECT?

a. The source IP address is 32 bits in length and identifies the full IP address of the source

node.

b. The destination address is 128 bits in length and identifies the full IP address of the

receiving node.

c. The Time to Live (TTL) field indicates the duration that the packet can remain on the

network before it is discarded.

d. The payload length indicates the size of the payload, or data carried by the packet.

e. The flow label indicates which flow, or sequence of packets issued from one source to one

or multiple destinations, the datagram belongs to.

1. only a and b

2. only b, d and e

3. only a, c, d and e

4. only a and c

Question 24

Which one of the following commands can you use to view a Windows workstation's ARP

(Address Resolution Protocol) table?

1. arp -all

2. arp -n

3. arp -a

4. arp -?


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Question 25

Suppose your computer's IP address is 195.61.9.188, and your network administrator has not

subnetted the network to which you're connected. What is your computer's subnet mask?

1. 255.0.0.0

2. 255.255.0.0

3. 255.255.255.0

4. 255.255.255.255

Question 26

A (n) ____ address represents any one interface from a group of interfaces, any one of which

can accept a transmission.

1. anycast

2. unicast

3. multicast

4. singlecast

Question 27

If you are connected to a network that uses DHCP (Dynamic Host Configuration Protocol), and

you need to terminate your Windows workstation's DHCP lease, which of the following

commands would you use?

1. ipconfig /term

2. ipconfig /exit

3. ipconfig /release

4. ipconfig /stop

Question 28

Study the following screen dump from a computer running Windows XP. Is APIPA (Automatic

Private IP Addressing) enabled on this computer?

1. Yes.

2. No.

3. The diagram does not provide any information on APIPA.

Question 29

In the domain name www.google.com, ____ is the (TLD) top-level domain.

1. http

2. www

3. google

4. com

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Question 30

Why is TFTP (Trivial File Transfer Protocol) a LESS SECURE protocol than FTP (File Transfer

Protocol)?

1. TFTP allows for multiple simultaneous connections to a server and FTP limits the number

of simultaneous connections to one.

2. TFTP does not require a logon ID and password to connect to the server and FTP does.

3. TFTP is not capable of encrypting transmissions and FTP is.

4. TFTP displays the servers MAC and IP address when responding to requests and FTP

does not.

Question 31

Which one of the following statements regarding signal bounce is TRUE?

1. It is a phenomenon that occurs when the bus is terminated and signals continue to

traverse the network.

2. It is a phenomenon that occurs when the bus is not terminated and signals travel endlessly

between the two ends of the network.

3. It is a phenomenon that occurs when the bus is not terminated and the signals are

terminated.

4. It is a phenomenon that occurs when both the bus and the signals are terminated.

Question 32

Which one of the following is NOT a characteristic of a hybrid star-wired ring topology?

1. It uses the physical layout of a star in conjunction with the ring logical topology.

2. This hybrid topology benefits from the fault tolerance of the star topology.

3. Token ring networks as specified in IEEE 802.5 use this hybrid topology.

4. This topology forms the basis for modern Ethernet networks, which commonly use

switches or routers as the connectivity devices.

Question 33

The ring logical topology is also used by the .

1. star-wired ring hybrid physical topology

2. star-wired bus hybrid physical topology

3. ring-wired bus hybrid physical topology

4. bus-wired star hybrid physical topology


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Question 34

Which statements regarding backbone networks are INCORRECT?

a. A serial backbone consists of two or more internetworking devices connected to each

other by a single cable in a daisy-chain fashion.

b. In a parallel backbone, a single router or switch is the highest layer of the backbone.

c. A collapsed backbone allows you to interconnect different types of subnetworks.

d. The following diagram depicts a simple distributed backbone.

1. a and d

2. b, c and d

3. only b and d

4. a and c

Question 35

You are part of a team of engineers who work for an ISP (Internet Service Provider) that

connects large data centers, telephone companies, and their customers throughout

Johannesburg and Pretoria. Management has decided that the company can make large profits

by promising the utmost QoS (Quality of Service) to certain high-profile customers. Which one

of the following switching methods will best guarantee the promised QoS?

1. Circuit switching

2. MPLS (Multiprotocol Label Switching)

3. Packet switching

4. Message switching

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Question 36

Which of the following statements regarding the Physical layer standards for fiber-optic cable

are TRUE?

a. 100Base-FX requires multimode fiber containing at least two strands of fiber.

b. Organizations switching, or migrating, from UTP to fiber media can combine 100Base-TX

and 100Base-FX within one network.

c. The 1000 in 1000Base-LX stands for 1000 Mbpsor 1 Gbpsthroughput. Base stands

for broadband transmission, and LX represents its reliance on long wavelengths of

13000 nanometers.

d. 1000BaseSX is similar to 1000Base-FX in that it has a maximum throughput of 100 Gbps.

However, it relies on only multimode fiber-optic cable as its medium.

1. only a and b

2. only b, c and d

3. only c and d

4. a, b, c and d

Question 37

In which of the following examples do the workstations necessarily share a collision domain?

1. Two computers connected to the same hub

2. Two computers connected to the same switch

3. Two computers connected to the same router

4. Two computers connected to the same access server

Question 38

Within Ethernet frame types, the ____ signals to the receiving node that data is incoming and

indicates when the data flow is about to begin.

1. SFD (start-of-frame delimeter)

2. header

3. preamble

4. frame

Question 39

Buses differ according to their ____.

1. connectors

2. resistance

3. capacity

4. speed


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Question 40

The following diagram illustrates a .

1. SFP (small form-factor pluggable) transceiver for use with fiber connections

2. GBIC (Gigabit interface converter) with an RJ-45 port

3. Expansion board NIC

4. PCIe (Peripheral Component Interconnect Express) expansion board NIC

Question 41

A ____ is a repeater with more than one output port.

1. bridge

2. switch

3. hub

4. router

Question 42

Which one of the following statements regarding bridges is NOT TRUE? Bridges

_______________.

1. can interpret physical addressing information

2. can move data more rapidly than older routers

3. are protocol-dependent

4. add length beyond the maximum limits that apply to segments

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Question 43

You are asked to configure a backbone switch that connects servers supplying oceanic and

atmospheric data to mariners and pilots around the world. Your networks traffic load is very

high at all times, day and night. What type of switching do you configure the switch to use?

1. Bypass switching

2. Store-and-forward switching

3. Cut-through switching

4. Message switching

Question 44

Switches that operate anywhere between Layer 4 and Layer 7 of the OSI Model are also known

as .

a. content switches

b. application switches

c. routing switches

1. a or b

2. b or c

3. a or c

4. only a

Question 45

What is a routers convergence time?

1. The time a router takes to interpret Layer 2 addressing information for any given frame

2. The maximum amount of time a router is allowed for choosing the best path

3. The time it takes for a router to recognize a best path in the event of a change or network

outage

4. The time it takes for border routers to exchange routing table information

Question 46

The individual geographic locations connected by a WAN are known as ____.

1. WAN sites

2. WAN links

3. network service providers

4. central offices


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Question 47

Study the following list of CHARACTERISTICS depicting the advantages and disadvantages

regarding WAN topologies:

Advantages

Single connection failure affects one location Shorter data paths between any two sites Expansion: simple, less costly

Disadvantage

Central site failure can bring down entire WAN

The above list describes the advantages and disadvantages of a topology WAN

1. ring

2. star

3. bus

4. mesh

Question 48

Which one of the following statements regarding PON (Passive optical network) is

INCORRECT?

1. A PON is a network in which a carrier uses fiber-optic cabling to connect with multiple

endpoints.

2. In a PON, repeaters are the connectivity devices that intervene between a carrier and its

customer.

3. In the point-to-multipoint structure of a PON, the single endpoint at the carriers central

office is known as the networks OLT (optical line terminal).

4. PONs can handle one of several transmission technologies, including Ethernet, ATM

(Asynchronous Transfer Mode) and SONET (Synchronous Optical Network).

Question 49

Suppose you work for a bank and are leasing a frame relay connection to link an automatic

teller machine located in a rural grocery store with your bank's headquarters. Which of the

following circuits would be the best option, given the type of use this automatic teller machine

will experience?

1. DLC (dedicated leased circuit)

2. PVC (permanent virtual circuit)

3. SVC (switched virtual circuit)

4. ALC (automatic leased circuit)

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Question 50

The "?" in the above diagram depicts a link.

1. BRI (Basic Rate Interface)

2. PRI (Primary Rate Interface)

3. DRI (Data Rate Interface)

4. CRI (Channel Rate Interface)

Question 51

Which one of the following statements regarding T-Carriers is INCORRECT?

1. T-carrier standards specify a method of signalling, which means they belong to the

Physical layer of the OSI model.

2. Multiplexing enables a single T1 circuit to carry 24 channels, each capable of 64-Kbps

throughput; thus, a T1 has a maximum capacity of 24 x 64 Kbps, or 1.544 Mbps.

3. A T3 circuit can carry the equivalent of 672 voice or data channels giving the equivalent of

274.176 Mbps.

4. A fractional T1 is best suited to businesses that expect their traffic to grow and that may

require a full T1 eventually, but cant currently justify leasing a full T1.


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Question 52

The following diagram traces the path of an ADSL (Asymmetric Digital Subscriber Line)

connection from a home computer, through the local loop, and to the telecommunication's

carrier's switching facility. Identify devices 'A', 'B' and 'C'.

1. splitter; DSL modem; DSLAM (DSL Access Multiplexer)

2. CSU/DSU (Channel Service Unit/Data Service Unit); cable modem; virtual circuit

3. NIU (Network Interface Unit); splitter; SVC (Switched Virtual Circuit)

4. terminal adapter; demarcation point; NT2 (Network Termination 2)

Question 53

Broadband cable requires many subscribers to share the same local line, thus raising concerns

about ____ and actual (versus theoretical) throughput.

1. access

2. costs

3. noise

4. security

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Question 54

Which one of the following statements regarding ATM is INCORRECT?

1. ATM relies on virtual circuits.

2. On an ATM network, routers determine the optimal path between the sender and receiver

then establish this path before the network transmits data.

3. ATM is typically considered a packet-switching technology.

4. ATM is a connection-oriented technology

Question 55

The data rate of a particular SONET ring is indicated by its ____, a rating that is internationally

recognized by networking professionals and standards organizations.

1. OC (Optical Carrier) level

2. CIR (Committed Information Rate)

3. BRI (Basic Rate Interface)

4. DS0 (Digital Signal, Level 0)

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Assignment 1 Semester 2