Which technique is used by Ethernet to prevent collisions?

A.
Packet switching.

B.
CSMA/CD

C.
UDP

D.
NetBEUI

Explanation:
Carrier Sense Multiple Access / Collision Detection (CSMA/CD) is the physical medium signaling
protocol used by Ethernet. It helps prevent collisions by detecting traffic on the medium BEFORE
attempting to transmit.
Incorrect Answers:
A: Packet switching occurs at a higher layer/level. It is not involved with the physical layer, so it is
not involved with working with the medium. A sample of Packet Switching is frame relay which
runs at layer 2.
C: UDP is a transport layer (Layer 4) protocol, and many layers above the physical layer where
medium sensing occues.
D: NetBEUI is a data link (Layer 2) protocol which uses 802.2, and is above the workings of
physical medium sensing, where collisions would occur.