ITN Chapter 4
With odd parity (assume that the parity bit (in bold) has been placed at the end of each of the following) and a 7-bit ASCII code, which of the following is incorrect? 01101011 00011011 00100101 10110110 11111110
00011011
The probability of detecting an error, given that one has occurred, using parity checking is about: 100% 0% 50% 75% 98%
50%
Only the sender of a data transmission needs to be concerned about the rules or protocols that govern how it communicates with the receiver True False
False
The distance between repeaters or amplifiers on a telephone circuit is determined by the amount of power gained per unit length of the transmission. True False
False
The two categories of network errors are: lost data and delimited data. True False
False
Transmission efficiency refers to the percentage of bits transmitted without errors. True False
False
With contention, a computer does not have to wait before it can transmit. A computer can transmit at anytime. True False
False
__________can obliterate a group of bits, causing a burst error. Cross-talk Attenuation Impulse noise Intermodulation noise White noise
Impulse noise
________ is the process of sending a signal to a client that gives its permission to transmit or asks it to receive. Contention Polling Pooling Carrier sense CRC
Polling
_____________ is an effective way to prevent impulse noise, cross talk, and intermodulation noise. Shielding wires Adding fluorescent lights Adding repeaters to a circuit Adding amplifiers to a circuit Shorting a circuit
Shielding wires
Cyclical redundancy check is one of the most popular polynomial error-checking schemes. True False
True
Ethernet has been refined over the years and is now formally standardized as IEEE802.3ac. True False
True
Forward error correction is commonly used in satellite transmission. True False
True
HDLC is very similar to the SDLC synchronous data link protocol. True False
True
In a network, the type of errors caused during data transmission can be controlled by the network hardware and software. True False
True
Media access controls refer to the need to control when computers transmit. True False
True
Overhead bits are used for error checking and marking the start and end of characters and packets. True False
True
Point-to-point Protocol is a byte-count-oriented protocol. True False
True
____________ refers to bits that have been changed, in error, from 1 to 0, or vice versa, in a data transmission. Contracted bits Polled bits Inverse multiplexed bits Flipped bits Bit delineation
Flipped bits
______________ controls errors by detecting and correcting them at the receiving end without retransmission of the original message. Hamming code Huffman encoding Front end processing Wave division multiplexing Hub polling
Hamming code
When we amplify the signal on an analog circuit, we also amplify any noise that is present on the circuit. True False
True
With roll-call polling, a server polls clients in a consecutive, pre-arranged priority list. True False
True
Which of the following is not a type of synchronous protocol? SDLC VT100 HDLC Ethernet PPP
VT100
_____________ is an effective way to prevent attenuation. Shielding wires Adding fluorescent lights Adding repeaters or amplifiers to a circuit Changing multiplexing techniques Shorting a circuit
Adding repeaters or amplifiers to a circuit
____________ is not a function of a data link protocol. Media access control Message delineation Amplitude shift keying Indicating when a message starts and stops Error control
Amplitude shift keying
Which of the following is true with respect to the data link layer? It accepts streams of bits from the application layer. It is responsible for getting a message from one computer to another (one node to another) without errors. It does not perform error detection. It performs routing functions. It organizes data from the physical layer and passes these coherent messages to the application layer.
It is responsible for getting a message from one computer to another (one node to another) without errors.
Which of the following is true about roll call polling? It can not be modified to increase priority of clients or terminals. It does not require a server or host or special device that performs the polling. It is also called token passing. It is a type of contention approach to media access control. It typically involves some waiting because the server has to wait for a response from the polled client or terminal.
It typically involves some waiting because the server has to wait for a response from the polled client or terminal.
TRIB, an acronym that relates to throughput, stands for: Throughput Reduction of Information Barriers Transmission Rate of Information Bits Throughput Rate of Iso-synchronous Bytes Transmission Regulation for Inverse-multiplexing Bands Trellis-coded Regulation of Information Bits
Transmission Rate of Information Bits
_________________ is defined as the total number of information bits divided by the total number of bits in the transmission. Asynchronous rate Protocol percentage Throughput Transmission Rate of Information Bits Transmission efficiency
Transmission efficiency
Attenuation refers to the loss of signal strength. True False
True
Contention is commonly used with Ethernet local area networks. True False
True
Using parity, the probability for detecting an error, given that one has occurred, is: about 50% for either even or odd parity about 70% for even parity and 30% for odd parity about 30% for even parity and 70% for odd parity about 0% for either even or odd parity about 100% for either even or odd parity
about 50% for either even or odd parity
Which of the following is way to reduce or eliminate crosstalk on a circuit, changing multiplexing techniques adding repeaters or amplifiers to a circuit reducing the length of the cable adding fluorescent lights shorting a circuit
changing multiplexing techniques
With contention: computers wait until the circuit is free before they send data the server or front end processor works consecutively through a list of clients to determine who should have access to the media the front end processor must wait for a response from the polled client or terminal one computer starts the poll and passes it to the next computer on the multipoint circuit there is never a chance for "collision," or two computers trying to send data at the same time
computers wait until the circuit is free before they send data
With __________ ARQ, the sender immediately sends the next message or packet of data. continuous immediate open window stop-and-wait halt and be recognized (HBR)
continuous
When the output signal from an amplifier on a circuit is different from the input signal, this is called _________________. intermodulation noise attenuation echo white noise cross-talk
cross-talk
Stop-and-wait ARQ uses ___________ type of data flow. full simplex half complex full duplex half duplex full complex
half duplex
In communication protocols, _________ are used to convey the user's meaning. information bits overhead bits stop bits start bits flag bits
information bits
If a signal with a frequency of 500 MHz combines with a another signal of 1500 MHz and they form a new signal of 2000 MHz; this is an example of: intermodulation noise attenuation echo white noise cross-talk
intermodulation noise
Which of the following is true about the data link protocol, Ethernet (IEEE 802.3)? it is not very popular it is a bit-oriented protocol it uses block check characters for error detection newer version permits jumbo frames it uses parity bits for error detection
newer version permits jumbo frames
In ARQ, a NAK: is sent by the recipient if the message was received without error is sent by the sender at the same time as it sends a data packet is sent by the recipient if the message contains an error refers to non-asynchronous Kermit technique means that the sender should continue with sending the next message
is sent by the recipient if the message contains an error
Which of the following is true about the data link protocol, PPP? it is commonly used in WANs it is a bit-oriented protocol it uses block check characters for error detection it was developed in the 1970s it uses parity bits for error detection
it is commonly used in WANs
The first sublayer of the data link layer is the logical link control sublayer media access control sublayer session sublayer physical sublayer transport sublayer
logical link control sublayer
Cross-talk: occurs when one circuit picks up signals in another is always bothersome because it has a high signal strength decreases with increased proximity of two wires decreases during wet or damp weather increases with lower frequency signals
occurs when one circuit picks up signals in another
On digital circuits, we use _________ to reshape the incoming signal and prevent attenuation. amplifiers repeaters multiplexers digitizers modems
repeaters
Another term for impulse noise is: Gaussian noise spikes attenuation cross-talk intermodulation noise
spikes
The primary source of error in data communications is: echoes intermodulation noise spikes attenuation cross-talk
spikes
With __________ ARQ, the sender pauses for a response from the receiver to alter each message or packet of data. open window halt and be recognized (HBR) sliding window stop and wait continuous
stop and wait
As part of the five-layer network model used in this textbook, the data link layer sits directly between: the physical and the application layers the network and the application layers the network and transport layers the physical and the application layers the physical and the network layers
the physical and the network layers
In general, controlled approaches: work better than contention approaches for small networks that have low usage work better than contention approaches for large networks that have high usage work better than contention approaches for all sizes of networks do not require a host, server, or active monitor to assign media access control have many collisions
work better than contention approaches for large networks that have high usage
