CISCOCCNA認證考試640-810題庫原題9

your boss at testking asks you about half-duplex and full-duplex ethernet. what are unique for halfduplex ethernet? (choose two) 
a. half-duplex ethernet operates in a shared collision domain. 
b. half-duplex ethernet operates in a private collision domain. 
c. half-duplex ethernet has higher effective throughput. 
d. half-duplex ethernet has lower effective throughput. 
e. half-duplex ethernet operates in a private broadcast domain.

answer: a d 
explanation: 
a single device could not be sending a frame and receiving a frame at the same time because it would mean that a collision was occurring. so, devices simply chose not to send a frame while receiving a frame. that logic is  called half-duplex logic. 
ethernet switches allow multiple frames to be sent over different ports at the same time. additionally, if only  one device is connected to a switch port, there is never a possibility that a collision could occur. so, lan  switches with only one device cabled to each port of the switch allow the use of full-duplex operation. full 
duplex means that an ethernet card can send and receive concurrently.