CH 4 MIS 140

The probability of detecting an error, given that one has occurred, using parity checking is about: 50% 75% 98% 0% 100%

50%

the probability of detecting an error, provided that one has occured, using cyclic redundancy checking is about >99% 0% exactly 100% 75% 50%

> 99%

With __________ ARQ, the sender immediately sends the next message or packet of data. a. continuous b. immediate c. open window d. stop-and-wait e. halt and be recognized (HBR)

Continuous

_____________ is an effective way to prevent impulse noise, cross talk, and intermodulation noise. Group of answer choices Shorting a circuit Shielding wires Adding fluorescent lights Adding amplifiers to a circuit Adding repeaters to a circuit

Shielding wires

____________ refers to bits that have been changed, in error, from 1 to 0, or vice versa, in a data transmission. Group of answer choices Contracted bits Flipped bits Polled bits Inverse multiplexed bits Bit delineation

Flipped bits

When we amplify the signal on an analog circuit, we also amplify any noise that is present on the circuit. True False

True

forward error correction is commonly used in satellite transmission True False

True

Which of the following is not a type of synchronous protocol? Group of answer choices HDLC SDLC Ethernet PPP VT100

VT100

As part of the five-layer network model used in this textbook, the data link layer sits directly between: the physical and the network layers the physical and the application layers the network and transport layers the network and the application layers

the physical and the network layers

If a computer transmits a message containing "ABC" and the destination computer receives "abc" as the message, the message is corrupted. true false

true

Media access controls refer to the need to control when computers transmit. true false

true

One type of forward error correction is the Hamming code. Group of answer choices True False

true

The data link layer accepts messages from the network layer and controls the hardware that transmits them. true false

true

__________can obliterate a group of bits, causing a burst error. Cross-talk Intermodulation noise White noise Impulse noise Attenuation

impulse noise

Media Access Control (MAC) is not very important to point to point with a half duplex configuration is not very important in LAN does not control when computers transmit is not very important in multipoint configuration is not very important in point to point with full duplex configuration

is not very important in point to point with full duplex configuration

which of the following is true with respect to the data link layer it performs error detection it performs routing functions it accepts streams of bits from the application layer

it performs error detection

Data transmission errors are typically uniformly distributed in time True False

False

Impulse noise is caused by the thermal agitation of electrons. True False

False

ARQ means that: a. a receiver that detects an error in a message simply asks the sender to retransmit the message until it is received without error b. the common carrier Automatically Returns Queries to the subscriber upon receipt of such queries c. a sender is using a data link protocol called Asynchronous Repeating reQuest d. a fiber optic cable meets the American Registered Quality, a certification standard for use in high-quality data communication transmission lines e. a sender is using a parity scheme called Array Resource Quality

a receiver that detects an error in a message simply asks the sender to retransmit the message until it is received without error

Using parity, the probability for detecting an error, given that one has occurred, is: a. about 50% for either even or odd parity b. about 70% for even parity and 30% for odd parity c. about 30% for even parity and 70% for odd parity d. about 0% for either even or odd parity e. about 100% for either even or odd parity

about 50% for either even or odd parity

___________ is not a function of a data link protocol message delineation error control media access control amplitude shift keying indicating when a message starts and stops

amplitude shift keying

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is: echo spiking intermodulation noise attenuation white noise

attenuation

Errors on a network can occur: Group of answer choices only due to Gaussian noise only on dial-up type of circuits because of noise on the line only due to lightning strikes only on poorly maintained networks

because of noise on the line

Calculating the actual throughput of a data communication network is: far less complicated if the system operates on a contention basis not normally required for synchronous networks because they are so fast not needed for satellite-based networks simple because packet size is the primary factor affecting throughput complex because many factors affect throughput

complex because many factors affect throughput

When a signal is reflected back to the transmitting equipment, it is called a(n) _________. white noise attenuation echo impulse noise crosstalk

echo

Most computer networks managed by a host mainframe computer use contention media access control. true false

false

Parity checking can only detect an error when an even number of bits are switched. 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

which of the following is true about roll call polling it can not be modified to increase priority of clients or terminals it is a type of contention approach to media access control it is also called token passing it does not require a server or host or special device that performs polling 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

The two sublayers of the data link layer consist of the media access control sublayer and the________ . logical link control sublayer network control sublayer physical sublayer session sublayer transport sublayer

logical link control sublayer

Which of the following is way to reduce or eliminate crosswalk on a circuit shorting a circuit adding repeaters or amplifiers to a circuit adding fluorescent lights reducing the length of the cable physically separating the cables from other communication cables

physically separating the cables from other communication cables

________ is the process of sending a signal to a client that gives its permission to transmit or asks it to receive. Group of answer choices Polling CRC Carrier sense Contention Pooling

polling

which of the following is not an error detection method used in the data link layer cyclic rendundancy checking CRC 32 parity checking pulse code checking odd parity

pulse code checking

with_____ ARQ, the sender pauses for a response from the receiver to alter each message or packet of data continous open window halt and be recognized (HBR) stop and wait sliding window

stop and wait

The physical and data link layers of wired Ethernet have been refined over the years as a collection of standards under the IEEE 802.3 workgroup. true false

true

Token passing is a term that refers to hub polling, in which one computer starts a poll and passes it to the next computer on a multipoint circuit. true false

true

With roll-call polling, a server polls clients in a consecutive, pre-arranged priority list. true false

true

In general, controlled approaches: work better than contention approaches for large networks that have high usage have many collisions work better than contention approaches for all sizes of networks do not require a host, server, or active monitor to assign media access control work better than contention approaches for small networks that have low usage

work better than contention approaches for large networks that have high usage