Quick Definition
A network segment where two devices can cause a collision if they transmit simultaneously.
A collision domain is a network segment where a frame transmitted by one device can collide with a frame transmitted by another device at the same time. In legacy hub-based networks, all ports shared one collision domain. Modern Ethernet switches give each port its own collision domain by operating in full-duplex mode, eliminating collisions entirely. The term is still tested in CCNA because it is foundational to understanding why switches replaced hubs.
A hub extends one collision domain across all its ports. A switch gives each port its own collision domain but merges broadcast domains (unless VLANs are used).
A collision domain is a network segment where a frame transmitted by one device can collide with a frame transmitted by another device at the same time. In legacy hub-based networks, all ports shared one collision domain. Modern Ethernet switches give each port its own collision domain by operating in full-duplex mode, eliminating collisions entirely. The term is still tested in CCNA because it is foundational to understanding why switches replaced hubs.
A hub extends one collision domain across all its ports. A switch gives each port its own collision domain but merges broadcast domains (unless VLANs are used).
Collision Domain falls under the Network Fundamentals domain of the 200-301 exam. Understanding it in context with related terms like broadcast-domain and mac-address is essential for answering scenario-based questions correctly.