What is a true statement about VLANs and broadcast domains?

• A. VLANs isolate broadcast domains, reducing broadcast traffic to within each VLAN.
• B. VLANs merge broadcast domains to simplify management.
• C. VLANs do not affect broadcast domains.
• D. VLANs increase collision domains across the network.

Answer: (A)

VLANs divide broadcast domains. When devices are placed in a VLAN on a switch, broadcasts from any device stay within that VLAN and don’t reach devices in other VLANs. The switch tags and segments traffic so the broadcast domain is confined to its own VLAN, which reduces the amount of broadcast traffic seen network-wide. If devices in different VLANs need to talk, inter-VLAN routing (via a router or a layer-3 switch) is required. The other statements aren’t correct because VLANs do not merge broadcast domains; they isolate them, and while switches create separate collision domains per port, VLANs’ primary role is about broadcast-domain separation rather than increasing collision domains.