IS457 MIDTERM

Chapter 1,1,The characteristics of a data communication system?

"delivery, accuracy, and jiter"

,2, The components of a data communication system?

"message, sender, medium"

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

the geometric size of the network

,4,The largest geographic area a wide area network (WAN) can span is

the world

,5,Data can flow only in one direction all of the times in a \_________ mode.

simplex

,6,Data can flow in both directions all the times in a \_________ mode.

full duplex

,7,Which of the following is not one of the network criteria?

multipoint

,8,"In a \_____________ communication, the media needs to be shared between devices"

multipoint

,9,"In a \_____________ communication, the media is dedicated."

point-to-point

,10,"In a fully connected mesh topology with six computers, we need \________ links."

15

,11,"In a star topology with six computers, we need \________ links."

6

,12,An RFC (request for comments) is labeled ________ if it must be implemented by all Internet systems.

required

,13,The TCP/IP protocol suite consists of \_______ layers.

five

,14,A router is involved in \____________ layers of the TCP/IP protocol suite.

three

,15,A link-layer switch is involved in \______________ layers of the TCP/IP protocol suite.

two

Chapter 2,1,\_______ data are continuous and take continuous values.

Analog

,2,\_______ data have discrete states and take discrete values.

Digital

,3,\_______ signals can have only a limited number of values in a time interval.

Digital

,4,\_______ describes the position of the waveform relative to time 0.

Phase

,5,A simple sine wave can be represented by one single spike in the \_____ domain.

frequency

,6,"As frequency increases, the period \________."

decreases

,7,\________ is a type of transmission impairment in which the signal loses strength due to the resistance of the transmission medium.

Attenuation

,8,\________ is a type of transmission impairment in which the signal loses strength due to the different propagation speeds of each frequency that makes up the signal.

Distortion

,9,\________ is a type of transmission impairment in which an outside source such as crosstalk corrupts a signal.

Noise

,10,Baseband transmission of a digital signal is possible only if we have a \____ channel.

lowpass

,11,"If the available channel is a \____ channel, we cannot send a digital signal directly to the channel."

bandpass

,12,"For a \______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate."

noiseless

,13,"For a \______ channel, we need to use the Shannon capacity to find the maximum bit rate."

noisy

,14,The \_________ product defines the number of bits that can fill the link.

bandwidth-delay

,15,"\___________ conversion involves three techniques: line coding, block coding, and scrambling."

Digital-to-digital

,16,Block coding can help in \_______ and \_________ at the receiver.

synchronization and error detection

,17,\________ is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit group.

Block coding

,18,The most common technique to change an analog signal to digital data is called \__________.

PCM (pulse code modulation)

,19,\______ finds the value of the signal amplitude for each sample; \____ finds the change from the previous sample.

PCM; DM (pulse code modulation; delta modulation)

,20,"ASK, PSK, FSK, and QAM are examples of \________ conversion."

digital-to-analog

,21,"AM, FM, and PM are examples of \________ conversion."

analog to analog

,22,"In QAM (quadrature amplitude modulation), both ________ of a carrier frequency are varied."

amplitude and phase

,23,How many carrier frequencies are used in BASK?

1

,24,How many carrier frequencies are used in BFSK ?

2

,25,How many carrier frequencies are used in BPSK ((binary phrase shift keying) ?

1

,26,Which multiplexing technique is used for digital signals?

TDM (time division multiplexing)

,27,Which multiplexing technique involves signals composed of light beams?

WDM (wavelength division multiplexing)

,28,\________ is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link.

Multiplexing

,29,\____ is designed to use the high bandwidth capability of fiber-optic cable.

WDM (wavelength division multiplexing)

,30,"The \_______ technique uses M different carrier frequencies that are modulated by the source signal. At one moment, the sign modulates one carrier frequency; at the next moment, the signal modulates another carrier frequency."

FHSS (frequency hopping spread spectrum)

,31,The \______ technique expands the bandwidth of a signal by replacing each data bit with n bits using a spreading code.

DSSS (direct sequence spread spectrum)

,32,Transmission media are usually categorized as \_______.

guided or unguided

,33,Twisting in a twisted-pair help reduce the \__________.

noise

Chapter 3,1,Communication at the data-link layer is \___________________.

node-to-node

,2,"If the sender is a host and wants to send a packet to another host on the same network, the logical address that must be mapped to a physical address is \______."

the destination IP address in the datagram header

,3,An ARP(address resolution protocol) reply is normally _______.

unicast

,4,A packet at the data-link layer is normally called a   \_______.

frame

,5,An ARP (address resolution protocol) request is normally _______.

broadcast

,6,"In a \________________ link, the link is not shared between devices."

point-to-point

,7,Which of the following best describes a single-bit error?

A single bit per data unit is inverted.

,8,Which error detection method uses one's complement arithmetic?

Checksum

,9,Which error detection method consists of just one redundant bit per data unit?

Simple parity check

,10,Which error detection method involves polynomials?

CRC (cyclic redundancy check)

,11,"If the ASCII character G is sent and the character D is received, what type of error is this?"

Burst

,12,"If the ASCII character H is sent and the character L is received, what type of error is this?"

Single bit

,13,"In cyclic redundancy checking, what forms the check bits?"

The remainder

,14,"In CRC, if the dataword is 111111, the divisor 1010, and the remainder 110, what is the codeword at the receiver?"

111111110

,15,"At the CRC generator, \_______ is (are) added to the dataword after the division process to create the codeword."

the remainder

,16,"In CRC, the quotient at the sender \_______."

is discarded

,17,"At the CRC checker, \_______ means that the dataword is damaged."

a nonzero remainder

,18,"A codeword with of 10  bits has only four 0s, how many terms are in the polynomial representation of this code."

6

,19,How many bits are in the divisor if we use CRC-8?

9

,20,Checksum uses \____________ addition.

one’s complement

,21,"To detect five errors, the Hamming distance between each pair of codewords should be at least\_________."

6

,22,A checksum can  \_________ errors.

both detect and correct

,23,The shortest frame in HDLC protocol is usually the \_______ frame.

supervisory

,24,The HDLC \_______ field defines the beginning and end of a frame.

flag

,25,"In the PPP frame, the \_______ field defines the contents of the data field."

protocol

,26,"In the PPP frame, the \_______ field has a value of 11111111 to indicate the broadcast address of HDLC."

address

,27,"In byte stuffing, we need sometimes to add a \___________ in the payload."

ESC (electronic stability control) byte

,28,"In bit stuffing, we sometimes need to add an extra  \___________ bit in the payload."

0’s

,29,PPP is a \________ oriented protocol

byte

,30,In the \_______ random-access method collision is avoided.

CSMA/CA

,31,\_______ is (are) a channelization protocol.

"FDMA, TDMA, and CDMA"

,32,"In the \_______ random-access method, stations do not sense the medium."

ALOHA

,33,The vulnerable time for a pure ALOHA is \__________ the one for SLOTTED ALOHA.

greater than

,34,"In CDMA, we use different \___________ to achieve channelization."

codes

,35,"In TDMA, we use different \___________ to achieve channelization."

time slots

Chapters 4-5,1,"Given the Ethernet address 01011010 00010001 01010101 00011000 10101010 00001111 in binary, what is the address in hexadecimal notation?"

5A:11:55:18:AA:0F

,2,"If an Ethernet destination address is 07:01:02:03:04:05, then this is an \______ address."

multicast

,3,"If an Ethernet destination address is 08:07:06:05:44:33, then this is an \______ address."

unicast

,4,The \_______ layer of Ethernet consists of the LLC sublayer and the MAC sublayer.

data link

,5,The \_____ sublayer is responsible for the operation of the CSMA/CD access method and framing.

MAC

,6,"In Ethernet addressing, if all the bits are 1s, the address is \_________."

broadcast

,7,"In the Ethernet, the \_______field is actually added at the physical layer and is not (formally) part of the frame."

preamble

,8,"In the Ethernet frame, the \_______ field contains error detection information."

CRC

,9,The largest portion of the bandwidth for ADSL carries \_______.

downstream data

,10,The traditional cable TV system used \________cable end to end.

coaxial

,11,SONET uses \_______ TDM multiplexing.

synchronous

,12,Which of the following statements about wired and wireless LANs is correct?

Both operate in the lower two layers of the TCP/IP protocol suite.

,13,"IEEE has defined the specifications for a wireless LAN, called \_______, which covers the physical and data link layers."

IEEE 802.11

,14,"In IEEE 802.11, a \___ is made of stationary or mobile wireless stations and an optional central base station, known as the access point (AP)."

BSS

,15,"In IEEE 802.11, a BSS without an AP is called \_________."

an ad hoc architecture

,16,"In IEEE 802.11, a BSS with an AP is sometimes referred to as \____________."

an infrastructure network

,17,"In IEEE 802.11, communication between two stations in two different BSSs usually occurs via two \________."

APs