ch. 4 data comm

inter modulation noise

An example of _______ is when a signal with a frequency of 500 MHz combines with another signal of 1500 MHz and they form a new signal of 2000 MHz

true

Crosstalk occurs when the signal transmitted on one circuit or channel of a transmission systems creates an undesired effect in another circuit or channel.

true

If a computer transmits a message containing "ABC" and the destination computer recieves "abc" as the massage, the message is corrupted

false

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

true

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

spikes

The most common cause of burst errors is _____.

impulse noise

The most common source of data communications errors is/are

over 99%

Given that one has occurred, the probability of detecting an error using cyclic redundancy checking is:

50%

Given that one has occurred, the probability of detecting an error using parity checking is about:

amplitude shift keying

Which of the following is not a function of a data link protocol?

it is responsible for getting a message from one computer (node) to another without errors

Which of the following is true with respect to the data link layer?

false

With contention, a computer does not have to wait before it can transmit. It can transmit anytime.

computers must wait until the circuit is free before they can send data

With contention:

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

ARQ means that:

white noise

Background static on radios and telephones is called:

true

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

repeaters

On digital circuits, ______ are used to reshape the incoming signal and prevent attenuation

transmission efficiency

is defined as the total number of information bits divided by the total number of bits in the transmission

polling

is the process of sending a signal to a client that gives it permissiion to transmit or asks it to receive.

flipped bits

refers to bits that have been changed from 1 to 0, or vice versa, during data transmission between sender and receiver