Which was the first version of the Data Over Cable Service Interface Specification (DOCSIS) that enabled multiple downstream and upstream channels to be used to transport data to and from a single modem?

DOCSIS 3.0 is recognized as the first version of the Data Over Cable Service Interface Specification that introduced the concept of bondable channels, allowing multiple downstream and upstream channels to be utilized simultaneously for data transmission. This innovation vastly increased the overall data throughput and capacity, which was a significant advancement over previous versions. DOCSIS 1.0 and 2.0 did not support channel bonding; they operated using a single upstream and downstream channel for data transfer. DOCSIS 4.0, while advanced, builds on the foundations laid by DOCSIS 3.0 and focuses on enhancements for future broadband capabilities rather than introducing the multi-channel feature. Thus, DOCSIS 3.0 is the correct answer, as it marks the significant upgrade that enabled improved performance through multi-channel operation.