What is the unit of data transferred by an ATM network?

The correct answer is "Cell." An ATM (Asynchronous Transfer Mode) network uses fixed-size packets known as cells to transfer data. Each ATM cell is 53 bytes long, composed of 48 bytes of data and 5 bytes of header information. This fixed size allows for consistent and efficient data transfer, which is critical in time-sensitive applications like voice and video.

Using a standard cell structure helps ATM networks manage bandwidth effectively and maintain the quality of service, making it suitable for various types of traffic. While other terms like packet, frame, and segment refer to different data structures in other networking protocols (e.g., IP packets, Ethernet frames, TCP segments), they do not apply to the fundamental unit of data in an ATM network. Therefore, the use of "Cell" specifically identifies the correct unit of transfer within this technology.