What is a VLAN and why is it used in networks?

• A. A service that ensures data integrity in wireless networks.
• B. A Virtual Local Area Network that segments broadcast domains, improving security and traffic management.
• C. A protocol for dynamic IP address assignment.
• D. A type of firewall that filters traffic between subnets.

Answer: (B)

A VLAN, or Virtual Local Area Network, is a way to divide a single physical network into multiple logical broadcast domains. This segmentation keeps broadcast and multicast traffic inside the same VLAN, which reduces unnecessary traffic across the network and makes security easier to manage because devices in different VLANs won’t see each other’s broadcasts unless you deliberately route between them. In practice, switches assign ports to specific VLANs and use 802.1Q tagging on trunk links to carry traffic for multiple VLANs; devices within the same VLAN can communicate directly at Layer 2, while inter-VLAN communication requires a router or Layer 3 switch to route traffic between VLANs. Common uses include separating departments (like engineering, HR, and guest networks) or isolating IoT devices for security and control. So the description that defines a VLAN as a Virtual Local Area Network that segments broadcast domains to improve security and traffic management accurately captures what VLANs do. The other options describe different concepts—data integrity services for wireless networks, DHCP for dynamic IP addresses, and firewalls between subnets—which are not what VLANs are.