Which of the following WAN services usually provides the highest bandwidth?

SONET (Synchronous Optical Network) is known for providing the highest bandwidth among the options listed. It is a standardized protocol that transmits digital data over optical fibers at very high speeds. SONET is capable of supporting bandwidths ranging from 51.84 Mbps to 10 Gbps and even higher in more advanced implementations. This capability makes SONET particularly suitable for enterprise and telecommunications environments where high-speed data transmission is crucial.

In comparison, DSL (Digital Subscriber Line) typically offers lower bandwidth, usually under 100 Mbps, depending on the specific technology and conditions. T1 lines provide a fixed bandwidth of 1.544 Mbps, primarily used for business connections. Frame Relay, which operates at various speeds, generally provides bandwidth in the range of 56 Kbps to 2 Mbps and is often not as fast or reliable as other options for high-bandwidth needs.

Overall, SONET is designed specifically for high-capacity requirements, which is why it stands out as the service providing the highest bandwidth.