Exam 1

Question 1

The word ________ refers to information presented in whatever form is agreed upon by the parties creating and using it.

Answer 1

data

Question 2

________ is the exchange of data between two devices via some form of transmission medium such as a wire cable.

Answer 2

Data communications

Question 3

The effectiveness of a data communications system depends on four fundamental characteristics. Which one of the following is not one of those four fundamental characteristics?

delivery

accuracy

timeliness

effectiveness

Answer 3

effectiveness

Question 4

Packets which are small segments of a larger messages can arrive out of sequence and at different times. Which one of the following refers to this variation in the packet arrival time?

Jitter

Delay

Segmentation

None of the other choices is correct answer

Answer 4

Jitter

Question 5

A data communications system has five components. Which one of the following is not one of those five components?

Message

Sender

Receiver

Data

Protocol

Answer 5

Data

Question 6

In data communications, text is represented as a _____________.

Answer 6

Bit patter

Question 7

Which one of the following is not one of the transmission modes?

simplex

duplex

half-duplex

full-duplex

Answer 7

duplex

Question 8

Which of the following are the valid types of line configurations?

hybrid

point-to-point

multi-point

single point

Answer 8

all answers are correct

Question 9

Assume six devices are arranged in a mesh topology. How many cables are needed?

Answer 9

15

Question 10

Assume six devices are arranged in a mesh topology. How many ports are needed for each device?

Answer 10

5

Question 11

The _________ address, also known as the link address, is the address of a node as defined by its LAN or WAN.

Answer 11

transport

Question 12

The unit of data at the network layer is known as __________.

Answer 12

datagram

Question 13

Four levels of addresses are used in an internet following the TCP/IP protocols. Which one of the following is not one of these addresses?

physical

logical

port

transport

Answer 13

transport

Question 14

A local area network (LAN) is defined by _______________.

Answer 14

the geometric size of the network

Question 15

The length of address at the datalink layer is ________ bits.

Answer 15

48

Question 16

The _________ layer is responsible for delivering data units from one station to the next without errors.

Answer 16

data-link

Question 17

The length of address at the transport layer is ________ bits.

Answer 17

16

Question 18

The _______ uniquely defines a host on the Internet.

Answer 18

IP address

Question 19

The _________ layer is responsible for the source-to-destination delivery of a packet across multiple network links.

Answer 19

network

Question 20

when the communication is complex, we may need to divide the task between different layers, in which case we need a _________ at each layer.

Answer 20

protocol

Question 21

The length of address (IPv4) at the network layer is ________ bits.

Answer 21

32

Question 22

The _________ layer coordinates the functions required to transmit a bit stream over a physical medium.

Answer 22

physical

Question 23

In data communications and networking, a _________ defines the rules that both the sender and receiver and all intermediate devices need to follow to be able to communicate effectively.

Answer 23

protocol

Question 24

The unit of data at the transport layer is known as __________.

Answer 24

segment

Question 25

The __________ layer enables the users to access the network.

Answer 25

application

Question 26

The unit of data at the physical layer is known as __________.

Answer 26

bit

Question 27

True or False: TCP/IP is a hierarchical protocol suite made up of seven layers: physical, data-link, network, transport, session, presentation, and application

Answer 27

False

Question 28

The ________ address identifies a process on a host.

Answer 28

port

Question 29

The _________ layer is responsible for the process-to-process delivery of the entire message.

Answer 29

transport

Question 30

The unit of data at the data-link layer is known as __________.

Answer 30

frame

Question 31

The ________ can be analog or digital.

Answer 31

signals

Question 32

An _________ signal takes many values; a digital signal takes a limited number of values.

Answer 32

analog

Question 33

A simple periodic analog signal is a _________ which cannot be decomposed into simpler signals

Answer 33

sine wave

Question 34

The ________ refers to the amount of time, in seconds, a signal needs to complete one cycle.

Answer 34

period

Question 35

The _________, measured in hertz (Hz), refers to the number of periods in 1 s.

Answer 35

frequency

Question 36

The ________ is the distance a simple signal can travel in one period.

Answer 36

wavelength

Question 37

The range of frequencies contained in a composite signal is its _______.

Answer 37

bandwidth

Question 38

The _______ is the number of bits sent in 1 s, expressed in bits per second (bps).

Answer 38

bit rate

Question 39

The term _____ describes the position of the waveform relative to time 0.

Answer 39

phase

Question 40

Assume we need to download text documents at the rate of 200 pages per minute. What is the required bit rate of the channel? A page is an average of 24 lines with 80 characters in each line. If we assume that one character requires 8 bits, the bit rate is

Answer 40

3.072

Question 41

The _________ is the distance 1 bit occupies on the transmission medium.

Answer 41

bit length

Question 42

There are three causes of signal impairment which are all of the following except

Answer 42

jitter

Question 43

__________ means a loss of energy.

Answer 43

attenuation

Question 44

__________ means that the signal changes its form or shape.

Answer 44

distortion

Question 45

To show that a signal has lost or gained strength, engineers use the unit of the _________ which measures the relative strengths of two signals or one signal at two different points.

Answer 45

decibel

Question 47

True or False: If a signal travels from point 1 to point 2, the attenuation is computed by the formula dB = 10 log10 (P2/P1), where P1 and P2 are the powers at point 1 and 2.

Answer 47

True

Question 48

Suppose a signal travels through a transmission medium and its power is reduced to one-half. The loss of the power is which one of the following?

Answer 48

-3

Question 49

For a noiseless channel, the _______ bit rate formula defines the theoretical maximum bit rate which is given by the formula: BitRate = 2 × B × log2 L, where B is the bandwidth and L is the number of signal levels used to represent data.

Answer 49

Nyquist

Question 50

_______ capacity determines the theoretical highest data rate for a noisy channel which is given by the formula: Capacity, C = B × log2 (1 + SNR), where B is the bandwidth and SNR is the signal to noise ratio.

Answer 50

Shannon

Question 51

Consider an extremely noisy channel in which the value of the signal-to-noise ratio is almost zero. In other words, the noise is so strong that the signal is faint. For this channel what would be the capacity C?

Answer 51

0