Cisco CCNA mock exam questions sample test – Question 253

.Which of the following statements is NOT true regarding flow control?

A. It determines the rate at which the data is transmitted between the sender and receiver.
B. It can help avoid network congestion.
C. It manages the data transmission between devices.
D. It uses a cyclic redundancy check (CRC) to identify and remove corrupted data.

Correct Answer: D

Explanation:
It is NOT true that flow control uses a cyclic redundancy check (CRC) to identify and remove corrupted data. CRC is an error-checking schema that checks and removes corrupted
data. It is a calculation that is performed at the source. Flow control uses CRC to identify corrupted data for the purpose of requesting re-transmission, but it does not use CRC to
remove the corrupted data from the packet. If corruption is detected, the entire packet will be dropped.
Flow control is a function that ensures that a sending device does not overwhelm a receiving device. The following statements are TRUE regarding flow control:
Flow control controls the amount of data that the sender can send to the receiver.
Flow control determines the rate at which the data is transmitted between the sender and receiver.
Flow control of certain types can aid in routing data around network congestion
Types of flow control include windowing, buffering, and congestion avoidance:
Windowing- a process whereby the sender and receiver agree to increase or decrease the number of packets received before an acknowledgment is required based on network
conditions. This packet number is called a window. When conditions are favorable, the window size will be increased. During unfavorable network conditions, it will be decreased.
Buffering- the ability of a network card to store data received but not yet processed in a buffer (memory). This enhances its ability to handle spikes in traffic without dropping any
data.
Congestion avoidance – a process that some routing protocols can perform by adding information in each frame that indicates the existence of congestion on the network, allowing
the router to choose a different routing path based on this information.
Objective:
Network Fundamentals
Sub-Objective:
Compare and contrast OSI and TCP/IP models
References:
Cisco Documentation > Internetworking Technology Handbook > Routing Basics > Internet Protocols > TCP Packet Format