DAC stands for Direct Attach Cable, also known as a direct cable, direct copper cable, or high-speed cable. It is a low-cost solution designed for short-distance connections, often replacing optical modules. A DAC consists of cable assemblies permanently attached to module-like connectors on both ends, which plug directly into fixed ports. Unlike other cabling options, the connector head and copper cable are integrated and cannot be separated.

Direct-attached Twinax DAC cables are widely used in data center environments, supporting connections between SATA storage devices, RAID systems, core routers, switches, and servers operating at 10G, 40G, and 100G Ethernet, as well as InfiniBand. They provide a reliable, high-performance, and cost-effective solution across several deployment scenarios:

• Top of Rack (ToR) / Adjacent Rack: Passive or active DACs are ideal for very short distances, where minimizing cost is a key consideration.
• Middle of Row: Active DACs are typically preferred, as long as the transmission distance remains under approximately 15 meters.
• End of Row: DACs can also be effectively used here, provided the distance does not exceed about 15 meters.