Quick Definition
The set of all devices that receive a Layer 2 broadcast frame.
A broadcast domain is the group of all network devices that receive a broadcast frame sent by any one member. Layer 2 switches forward broadcasts out all ports except the receiving port, so all devices connected to a switch share one broadcast domain by default. Routers and Layer 3 interfaces break broadcast domains — each router interface or VLAN is a separate broadcast domain.
If SW1 has 24 ports and no VLANs configured, all 24 devices share one broadcast domain. If you create VLAN 10 and VLAN 20 and assign ports to each, you now have two broadcast domains.
VLANs create separate broadcast domains even on the same switch. This is a key VLAN benefit: reducing unnecessary broadcast traffic.
A broadcast domain is the group of all network devices that receive a broadcast frame sent by any one member. Layer 2 switches forward broadcasts out all ports except the receiving port, so all devices connected to a switch share one broadcast domain by default. Routers and Layer 3 interfaces break broadcast domains — each router interface or VLAN is a separate broadcast domain.
VLANs create separate broadcast domains even on the same switch. This is a key VLAN benefit: reducing unnecessary broadcast traffic.
If SW1 has 24 ports and no VLANs configured, all 24 devices share one broadcast domain. If you create VLAN 10 and VLAN 20 and assign ports to each, you now have two broadcast domains.
Broadcast Domain falls under the Network Fundamentals domain of the 200-301 exam. Understanding it in context with related terms like vlan and collision-domain is essential for answering scenario-based questions correctly.