Cyber/Net Chapter 4 Study Guide

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

50%

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

False

Only the sender of a data transmission needs to be concerned about the rules or protocols that govern how it communicates with the receiver.

False

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

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.

False

The two categories of network errors are: lost data and delimited data.

False

Transmission efficiency refers to the percentage of bits transmitted without errors.

False

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

False

____________ refers to bits that have been changed, in error, from 1 to 0, or vice versa, in a data transmission.

Flipped bits

Cyclical redundancy check is one of the most popular polynomial error-checking schemes.

True

Forward error correction is commonly used in satellite transmission.

True

HDLC is very similar to the SDLC synchronous data link protocol.

True

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

True

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

True

One type of forward error correction is the Hamming code.

True

Overhead bits are used for error checking and marking the start and end of characters and packets.

True

________ has essentially replaced SDLC and offers a larger sliding window.

HDLC

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

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

Undesirable stray electrical voltage can cause data communication errors.

True

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

True

Which of the following is not a type of synchronous protocol?

VT100

In communication protocols, _________ are used to convey the user's meaning.

information bits

Which of the following is true about the data link protocol, PPP?

is is commonly used in WANs

Media Access Control (MAC)

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

In ARQ, a NAK:

is sent by the recipient if the message contains an error

____________ is not a function of a data link protocol

Amplitude shift keying

Which of the following is not a controlled access method of media access control?

CSMA/CD

Data transmission errors are typically uniformly distributed in time.

False

Gaussian noise is a special type of attenuation.

False

In an odd parity-checking scheme, the parity bit is set to make the total number of ones in the byte (including the parity bit) an even number.

False

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

It performs error detection.

Which of the following is true about the data link protocol, SDLC:

It uses a special bit pattern called a flag at the beginning and end of every frame (or packet).

The data link layer uses the ________ to recognize the source and destination addresses.

MAC address

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

Transmission efficiency

Attenuation refers to the loss of signal strength.

True

Contention is commonly used with Ethernet local area networks.

True

Controlled access MAC approaches work better in a large network with high usage.

True

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

True

ARQ means that:

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:

about 50% for either even or odd parity

The loss of power a signal suffers as it travels from the transmitting computer to a receiving computer is:

attenuation

Asynchronous transmission:

each character is transmitted independently of all other characters

When a signal is reflected back to the transmitting equipment, it is called a(n) _________.

echo

The two sublayers of the data link layer consist of the media access control sublayer and the ________.

logical link control sublayer

Which of the following is way to reduce or eliminate crosstalk on a circuit?

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.

polling

Which of the following is not an error detection method used in the data link layer?

pulse code checking

The primary source of error in data communications is:

spikes

In general, controlled approaches:

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