Ch4 Flashcards
Media access controls refer to the need to control when computers transmit
T
The data link layer accepts messages from the network layer and controls the
hardware that transmits them.
T
Only the sender of a data transmission needs to be concerned about the rules or
protocols that govern how it communicates with the receiver.
F
As part of the five-layer network model used in this textbook, the data link layer sits directly
between:
a. the physical and the application layers
b. the network and the application layers
c. the network and transport layers
d. the physical and the application layers
e. the physical and the network layers
E
Which of the following is true with respect to the data link layer?
a. It accepts streams of bits from the application layer.
b. It is responsible for getting a message from one computer to another (one node to
another) without errors.
c. It does not perform error detection.
d. It performs routing functions.
e. It organizes data from the physical layer and passes these coherent messages to the
application layer.
B
____________ is not a function of a data link protocol.
a. Media access control
b. Message delineation
c. Amplitude shift keying
d. Indicating when a message starts and stops
e. Error control
C
The first sublayer of the data link layer is the
a. logical link control sublayer
b. media access control sublayer
c. session sublayer
d. physical sublayer
e. transport sublayer
A. Second sublayer is Media Access Control
What function does the Logical Link Control (LLC) sublayer perform within the Data Link Layer?
A) It converts data link layer PDUs into a stream of bits and controls the timing of transmission at the physical layer.
B) It ensures reliable, ordered, and error-checked delivery of data between communicating devices.
C) It establishes, maintains, and terminates connections between devices on a network.
D) It connects to and communicates with the network layer above.
D
At the receiving end in the Media Access Control (MAC) sublayer, what is the main task performed?
A) Translating a stream of bits into a coherent PDU
B) Controlling the physical hardware of the network interface
C) Ensuring no errors have occurred during transmission
D) Establishing connections between network devices
A
- What does the transmitting end do in the Logical Link Control (LLC) sublayer?
A) Surrounds the IP packet with an Ethernet frame
B) Controls when physical layer hardware can transmit bits
C) Ensures error-free transmission at the data link layer
D) Establishes connections between devices on a network
A
What is the primary responsibility of the transmitting end in the Media Access Control (MAC) sublayer?
A) Translating data link layer PDUs into a coherent message
B) Controlling when physical layer hardware can transmit bits
C) Ensuring error-free transmission at the network layer
D) Establishing connections between devices on a network
B
What is the primary task of the receiving end in the Logical Link Control (LLC) sublayer?
A) Removing the data link layer PDU and passing the contained message to the network layer
B) Controlling the physical hardware of the network interface
C) Ensuring the integrity of the IP packet
D) Establishing connections between network devices
A
Which task is specifically associated with the transmitting end in the Logical Link Control (LLC) sublayer?
A) Translating a stream of bits into a coherent PDU
B) Surrounding the IP packet with a data link layer PDU
C) Ensuring error-free transmission at the physical layer
D) Establishing connections between network devices
B
Which function is primarily associated with the Media Access Control (MAC) aspect of a data link layer protocol?
A) Detects and corrects transmission errors
B) Controls when computers transmit
C) Identifies the start and end of a message
D) Establishes connections between network devices
B
What is the primary role of error control in a data link layer protocol?
A) Controls when computers transmit
B) Detects and corrects transmission errors
C) Identifies the start and end of a message
D) Establishes connections between network devices
B
Which aspect of a data link layer protocol is responsible for ensuring that computers transmit data in an organized manner?
A) Error control
B) Media Access Control (MAC)
C) Message delineation
D) Connection establishment
B
What aspect of a data link layer protocol determines the boundaries of individual messages?
A) Media Access Control (MAC)
B) Error control
C) Message delineation
D) Connection establishment
C
What are the three major functions associated with a data link layer protocol?”
A) Media Access Control (MAC), Error control, Connection establishment
B) Error detection, Message delineation, Media Access Control (MAC)
C) Error control, Media Access Control (MAC), Message delineation
D) Connection establishment, Error control, Media Access Control (MAC)
C
Most computer networks managed by a host mainframe computer tend to use a form
of media access control called contention.
F. Contention: Computers wait for the circuit to be free before transmitting their data
With contention, a computer does not have to wait before it can transmit. A computer
can transmit at any time.
F. Computers wait for the circuit to be free before transmitting their data.
Media access control is not very important in point-to-point with full duplex configuration.
T. In point-to-point full-duplex configurations, media access control is not needed because only two computers are on the circuit and can transmit simultaneously.
Media access control is not very important in local area networks
F. MAC protocols can support networks ranging from small local area networks (LANs)
Media access control is not very important in a point-to-point with a half-duplex
configuration
F
What characteristic defines a multipoint circuit?
A) It uses different circuits for each connection.
B) It shares the same circuit among multiple connections.
C) It connects only two devices at a time.
D) It operates independently of other circuits.
B
Media access control is not very important in a multipoint configuration.
F
Media access control does not control when computers transmit.
F
In a contention, what defines a collision?
a) A computer’s failure to transmit data.
b) When two or more computers attempt to transmit data simultaneously.
c) The loss of data during transmission.
d) When a computer overheats due to excessive network activity.
B
Contention is widely used with Ethernet local area networks.
T
Roll call polling is a type of contention approach to media access control
F
Controlled access MAC approaches work well in a large network with high usage
T
There are three commonly used controlled access techniques: access requests, access
demands, and polling
F. just 2: access request and polling
In general, controlled approaches work better than contention approaches for small
networks that have low usage
F
In general, controlled approaches work better than contention approaches for large
networks that have high usage
T
In general, controlled approaches work better than contention approaches for all sizes of networks
F
In general, controlled approaches do not require a host, server, or active monitor to
assign media access control.
F
In general, controlled approaches have many collisions
F
Which of the following is not a controlled access method of media access control?
a. Token passing
b. CSMA/CD
c. polling
d. roll call polling
e. hub polling
B
In general, controlled approaches:
a. work better than contention approaches for small networks that have low usage.
b. work better than contention approaches for large networks that have high usage.
c. work better than contention approaches for all sizes of networks.
d. do not require a host, server, or active monitor to assign media access control.
e. have many collisions.
B
Which of the following best describes controlled access in a network environment?
A) Every device on the network can transmit data simultaneously.
B) Multiple devices control access to the circuit.
C) One device controls the circuit and determines which clients can transmit at what time.
D) Access to the shared circuit is unregulated.
E) Controlled access relies on a decentralized approach for managing network traffic.
C. Controlled Access: One device controls the circuit and determines which clients can transmit at what time:
+Controls access to the shared circuit
+Acts like a stop light
What is the primary function of a controlled access device in a network?
A) Transmit data to all connected clients simultaneously
B) Regulate access to a shared circuit
C) Monitor network traffic for security threats
D) Increase the speed of data transmission
B.Controlled Access: One device controls the circuit and determines which clients can transmit at what time:
+Controls access to the shared circuit
+Acts like a stop light
What is the primary role of controlled access in a wireless LAN (Local Area Network)?
A) Regulating the speed of data transmission
B) Determining which computer has access to the base station
C) Encrypting all data transmissions for security
D) Monitoring the signal strength of connected devices
B
In a wireless LAN environment, what does the controlled access mechanism determine?
A) Which devices are allowed to connect to the internet
B) Which computer has access to the central base station at any given time
C) The range of the wireless network
D) The type of data protocols used for transmission
B
How does controlled access operate in a wireless LAN?
A) It allows all devices to transmit data simultaneously
B) It grants exclusive access to the base station for one computer at a time
C) It randomly assigns access privileges to connected devices
D) It restricts access to the network based on device location
B. Wireless access point = wireless LAN
Which device typically controls access in a wireless LAN?
A) Modem
B) Router
C) Access point (base station)
D) Network interface card (NIC)
C
What is the main benefit of using controlled access in a wireless LAN?
A) Increased network speed
B) Enhanced signal strength
C) Reduced interference and data collisions
D) Greater range of connectivity
C
In the access request technique, what action do client computers take when they want to transmit data?
A) They immediately start transmitting data.
B) They send a request to the controlling device.
C) They wait for permission from other client computers.
D) They disconnect from the network temporarily.
B
Which of the following is an example of a device that controls access to the shared circuit in wireless networks?
A) Modem
B) Router
C) Wireless access point
D) Network switch
C
How does the controlling device manage data transmission in the access request technique?
A) By allowing all client computers to transmit simultaneously
B) By granting permission for one client computer at a time to transmit
C) By blocking all client computers from transmitting data
D) By slowing down the data transmission speed for all client computers
B
What role does the wireless access point play in the access request technique?
A) It encrypts all data transmissions for security purposes.
B) It connects client computers to the internet.
C) It controls access to the shared wireless medium.
D) It provides physical support for wireless devices.
C
How do client computers behave while one computer has permission to transmit data?
A) They continue transmitting data simultaneously.
B) They wait until the currently transmitting computer finishes.
C) They disconnect from the network.
D) They send requests to other client computers for permission to transmit
B
Polling is the process of permitting all clients to transmit or receive at any time
F. Polling is the process of sending a signal to a client computer that permits it to transmit.
________ is the process of sending a signal to a client that gives its permission to
transmit or asks it to receive.
a. Contention
b. Polling
c. Pooling
d. Carrier sense
e. CRC
B
What is polling in a network communication context?
A) Sending data to all clients simultaneously
B) Controlling access to the network through encryption
C) Sending a signal to a client computer permitting it to transmit
D) Filtering incoming data packets for security purposes
C
What role do client computers play in polling?
A) They determine the frequency of polling signals.
B) They store data that needs to be transmitted.
C) They control access to the network.
D) They encrypt the data before transmission.
B
How does the controlling device in polling interact with client computers?
A) It sends a signal to all clients simultaneously.
B) It randomly selects clients to send data.
C) It periodically checks each client to see if it has data to transmit.
D) It only communicates with the client that has the most data to transmit.
C
How does a client computer respond if it has no data to send during polling?
A) It sends a positive acknowledgment to the polling signal.
B) It encrypts the data before transmission.
C) It ignores the polling signal.
D) It responds negatively to the polling signal.
D
What is the purpose of the periodic polling of client computers by the controlling device?
A) To restrict access to the network based on location
B) To ensure that all client computers have a chance to transmit data
C) To prioritize certain clients over others based on data needs
D) To maximize network bandwidth for high-priority traffic
B
With roll-call polling, a server polls clients in a consecutive, pre-arranged priority list
T
Roll call polling cannot be modified to increase priority of clients or terminals
F
Roll call polling does not require a server, host, or special device that performs the
polling
F
Roll call polling is a type of contention approach to media access control
F
Roll call polling typically involves some waiting because the server has to wait for a
response from the polled client or terminal.
T
Which of the following is true about roll call polling?
a. It cannot be modified to increase priority of clients or terminals.
b. It does not require a server, host, or special device that performs the polling.
c. It is also called token passing.
d. It is a type of contention approach to media access control.
e. It typically involves some waiting because the server has to wait for a response
from the polled client or terminal.
E
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.
T
What action does a device take after receiving the token in hub polling?
A) It sends a message to all other devices on the network.
B) It transmits data if it has any and then passes the token to the next device.
C) It waits for another device to request permission to transmit.
B
How does the hub polling cycle restart?
A) When all devices have transmitted data once
B) When the hub sends a reset signal to all devices
C) When the token reaches the first device that initiated the polling process
D) When a device detects an error in data transmission
C
The two categories of network errors are lost data and delimited data
F. Corrupted data and Lost data
How are human errors typically controlled in a network system?
a) Through hardware mechanisms
b) Through application programs
c) Through physical controls
d) Through administrative controls
B
Which type of error is exemplified by a mistake in typing a number?
a) Hardware error
b) Software error
c) Human error
d) Network error
C
What is the primary control mechanism for human errors in network systems?
a) Network hardware
b) Application programs
c) Physical controls
d) Administrative controls
B
How are network errors typically controlled?
a) Through physical controls
b) Through application programs
c) Through network hardware and software
d) Through administrative controls
C
What is an example of a network error?
a) Software bug
b) Typing mistake in a number
c) Changing a bit value during transmission
d) Power outage
C
If a computer transmits a message containing “ABC” and the destination computer
receives “abc” as the message, the message is corrupted.
T
What is corrupted data?
a) Data stored in multiple locations
b) Data with redundant information
c) Data that is changed from its original form
d) Data transmitted with encryption
C
What is lost data?
a) Data stored in multiple locations
b) Data with redundant information
c) Data that cannot be recovered
d) Data transmitted with encryption
C
Which of the following best defines error rate?
a) The probability of a single bit being transmitted correctly
b) The frequency of errors in a given amount of transmitted data
c) The rate at which data is compressed during transmission
d) The duration of time it takes for data to be transmitted
B
How is error rate typically measured?
a) In bits per second (bps)
b) In hertz (Hz)
c) In percentage of successful transmissions
d) In terms of errors per unit of transmitted data
D
What does an error rate of “1 in 500,000” mean?
a) For every 500,000 bits transmitted, one bit is expected to be in error
b) For every 500,000 bits transmitted, all bits are expected to be in error
c) For every bit transmitted, there is a 500,000% chance of error
d) For every 500,000 errors, one bit is transmitted correctly
A
In a _________, more than one data bit is changed by the error-causing condition.
a. burst error
b. data rate shift
c. Trellis-coded modulation
d. uniform distribution
e. amplitude key shift
A
What is a burst error?
a) An error that occurs randomly in data transmission
b) An error where many bits are corrupted at the same time
c) An error caused by hardware malfunctions
d) An error that affects only a single bit in the data
B