Which type of network service operates at the Data Link Layer and is connection-oriented?

The correct answer is Frame Relay, which is a data link layer protocol designed for connecting devices on a wide area network (WAN). Being connection-oriented means that Frame Relay establishes a virtual circuit or logical connection before data transfer begins. This allows it to maintain the state of the connection, providing more reliable communication by confirming that data is being sent and received in the correct order, which is crucial for certain applications.

Within the context of the Data Link Layer, Frame Relay encapsulates frames with the necessary addressing and control information required for reliable transmission over the network. It uses local area network techniques in a WAN environment, effectively managing how data is transported between devices.

In contrast, the other options do not fulfill both criteria of operating at the Data Link Layer and being connection-oriented. Internet Protocol (IP) operates at the Network Layer and is inherently connectionless, as it does not establish a dedicated end-to-end connection. Asynchronous Transfer Mode (ATM) is a cell-based switching technology that operates at both the Network Layer and Data Link Layer but is not considered typically connection-oriented in the sense that it can also function in a connectionless manner. Ethernet, on the other hand, is primarily a connectionless service that operates at the Data Link Layer and does not establish