A LAN is best described as

• A. a layer 2 broadcast domain
• B. a group of endpoints in a single building
• C. a cloud service
• D. a WAN connection

Answer: (A)

A LAN is best described as a layer 2 broadcast domain. At the data link layer, devices within the same LAN use MAC addresses and are connected by switches that forward frames to destinations in the same local domain. A broadcast frame—like an ARP request—is delivered to every device on that same layer 2 network, unless segmentation is used with VLANs. Routers, not switches, separate these broadcast domains, so traffic between different networks must be routed at layer 3. That’s why a LAN isn’t defined as a cloud service or a WAN connection, and while it often sits in a single building, the defining characteristic is the shared layer 2 broadcast domain (which can be split into multiple domains with VLANs).