Simultaneous transmission between two or more network domain devices or nodes.

• A. Collision
• B. Congestion
• C. Interference
• D. Collusion

Answer: (D)

When two or more devices transmit at the same time on a shared network medium, their signals interfere with each other, causing a collision. This garbling is the term used to describe the problem in many Ethernet networks. In practice, CSMA/CD works by listening before transmitting; if the medium is free, a device starts sending, but if another device begins transmitting too, the signals collide. The devices then detect the collision, stop transmitting, wait a random backoff period, and attempt to transmit again. This concept is distinct from congestion (too much traffic overall, causing delays), interference (external noise or signals disrupting transmission), and collusion (not a standard networking term for this context). Understanding collisions also explains why switches, which create separate collision domains per port, reduce or eliminate these events on modern networks.