Which issue arises from not segmenting a network properly?

Improper network segmentation can lead to a situation known as a broadcast storm, which occurs when there is excessive broadcast traffic in the network. In a non-segmented network, broadcasts from one device can be sent to all devices on the same network segment. As devices respond to broadcasts or if there are multiple devices generating broadcasts, the amount of broadcast traffic can rise exponentially, saturating the network. This results in degraded performance, increased latency, and can even cause network outages, making it difficult for legitimate traffic to traverse the network efficiently.

By segmenting a network appropriately—such as using VLANs or separate physical networks—broadcast traffic can be contained within smaller segments, significantly reducing the risk of broadcast storms and maintaining overall network health and performance.

Other options, like increased security from limited access, higher network costs, and faster data transfer rates, do not directly relate to the consequences of failing to segment a network and instead describe benefits that may arise from proper segmentation or associated network changes.