What could be a consequence of not using a VLAN?

The consequence of not using a Virtual Local Area Network (VLAN) is that devices on the same network segment can communicate freely with one another, which can lead to traffic congestion. In a typical flat network where VLANs are not implemented, all devices share the same broadcast domain. This means that any broadcast traffic sent by one device will be received by all other devices on the network, leading to a significant increase in unnecessary traffic.

As more devices communicate without any segmentation, the amount of broadcast traffic can grow, causing delays and reduced network performance. Consequently, as network congestion happens, the overall efficiency and responsiveness of the network decrease, which can affect all devices connected to that network.

Using VLANs helps to segment traffic and restrict communication based on specific criteria, like department or function, allowing for improved performance and reduced congestion. It effectively limits broadcast traffic to only those devices that need to communicate with one another, improving overall network efficiency.