15. CSMACD

Learn how CSMA/CD works and why it was essential for managing traffic on shared Ethernet networks — an important networking concept that is tested on the CCNA exam and helps you understand why switches replaced hubs! In this video, you'll learn: - What CSMA/CD stands for — Carrier Sense Multiple Access with Collision Detection - Why CSMA/CD was needed on shared Ethernet networks using hubs and coaxial cable - How the carrier sense mechanism works — listening before transmitting - What multiple access means and why it creates the possibility of collisions - How collision detection works when two devices transmit simultaneously - What a jam signal is and how it notifies all devices of a collision - How the exponential backoff algorithm determines when a device retransmits after a collision - How the collision domain size affects the frequency of collisions and network performance - Why CSMA/CD is not used in modern full-duplex switched Ethernet - How understanding CSMA/CD explains the performance limitations of hub-based networks CSMA/CD is the mechanism that kept early shared Ethernet networks from collapsing under simultaneous transmissions. Understanding how it works explains why collision domains matter, why hubs are inefficient, and why full-duplex switched Ethernet was such a significant improvement — all key concepts for the CCNA exam. #systemengineer7131 #CCNA #CSMACD #Ethernet #CollisionDomain #HubVsSwitch #CiscoNetworking #CCNABoost #NetworkingTutorial #CCNA2026