What is the purpose of a VLAN?

Correct answer: Logically segment a physical network into multiple isolated networks

Option B is correct because a VLAN (Virtual Local Area Network) uses switch port tagging to create logical broadcast domains within a single physical switch fabric, isolating traffic between groups of devices as if they were on separate physical networks. Option A is incorrect because VLANs do not increase bandwidth; they segment traffic, which can reduce unnecessary broadcast traffic but do not add physical capacity to links. Option C is incorrect because VLANs provide logical separation, not encryption; traffic encryption requires protocols such as MACsec or upper-layer TLS. Option D is incorrect because VLANs do not replace routers; inter-VLAN routing still requires a Layer 3 device such as a router or a Layer 3 switch with routed interfaces.