Work out collision domain count instantly with clear inputs, formula shown and shareable results.
Each switch port is its own collision domain, so a full-duplex switched port has none at all in practice. A hub, by contrast, joins all of its stations into one shared half-duplex domain where CSMA/CD applies and bandwidth is divided between the stations. Counting domains is the classic way of showing why replacing hubs with switches multiplies usable capacity.
Domain count
collision domains = switch ports in use; nodes = (ports - hubs) + hubs x stations per hub; shared bandwidth per node = link speed / stations per hub
One per VLAN, regardless of port count. Collision domains and broadcast domains are separate concepts and only routing splits the latter.
Not on full-duplex links, where CSMA/CD is disabled entirely. Collisions only appear where legacy half-duplex hubs or misnegotiated duplex settings remain.