The maximum length of a QSFP+ (Quad Small Form-Factor Pluggable Plus) Direct Attach Copper (DAC) cable depends on the specific cable construction and the technology used. QSFP+ DAC cables are copper cables with QSFP+ connectors on both ends and are commonly used for short-distance, high-speed connections within data centers.

Typically, the maximum length of QSFP+ DAC cables is limited to a few meters. Common lengths for QSFP+ DAC cables include 1 meter, 3 meters, and 5 meters. The exact maximum length can vary based on the cable manufacturer, the cable gauge, and the specific design of the cable.

It's important to check the product documentation or datasheet provided by the manufacturer of the QSFP+ DAC cable for precise information on the maximum supported length. Using cables beyond the specified maximum length may result in signal degradation and performance issues.