At which layer does UDP operate?

UDP, or User Datagram Protocol, operates at the transport layer of the Internet Protocol Suite. This layer is responsible for providing end-to-end communication services for applications, which includes reliable or unreliable delivery of messages. The transport layer manages the flow of data between devices and ensures that data packets are delivered accurately and in order, if necessary.

UDP is specifically known for its simplicity and efficiency. Unlike TCP (Transmission Control Protocol), which also operates at the transport layer but includes additional functionalities for establishing connections and error checking, UDP does not guarantee delivery, order, or error correction. This makes UDP suitable for applications where speed is more critical than reliability, such as video streaming, online gaming, or VoIP.

The other options represent layers of the OSI model or the Internet Protocol Suite but do not pertain to the functionality of UDP. The network layer is responsible for routing packets across different networks, the application layer supports application services, and the data link layer controls how data is physically sent through the network, all of which are layers distinct from where UDP operates.