QNAP CAB-DAC15M-Q28B4 QSFP28 to 4x SFP28 100GbE Breakout DAC Cable
Overview
The CAB-DAC15M-Q28B4 is a 1.5-meter twinaxial direct attach breakout cable that fans a single QSFP28 100GbE port into four independent SFP28 25GbE links — letting you connect four 25GbE devices from one switch port without an optical transceiver or media converter in the path. The result is lower latency, zero SFP28 transceiver cost per link, and a cleaner rack wiring path for short top-of-rack runs. It is the right cable when you are aggregating 25GbE uplinks from servers, NAS units, or storage nodes into a 100GbE spine switch port and the cable run stays within 1.5 meters. For anything longer, passive DAC is the wrong medium — consider active optical cables instead. Browse the full QNAP networking line to match compatible switches and adapters.
Compatibility
Designed for use with QNAP 100GbE-capable switches and network adapters that expose a QSFP28 port, including configurations built around the QNAP QSW-series 100GbE switches. The four SFP28 ends connect to any standard 25GbE SFP28 host interface — QNAP NAS units fitted with 25GbE expansion cards (such as the QXG-25G series) and servers running 25GbE NICs are the primary targets. Also referenced in QNAP deployment guides alongside the QXG-100G2SF-E810 100GbE network card for high-throughput NAS-to-switch connectivity. The sibling SKU CAB-DAC15M-Q28 is the non-breakout 100GbE QSFP28-to-QSFP28 variant — confirm your port type before ordering. See direct attach cables for the full DAC lineup, and review your switch port inventory to verify QSFP28 availability before deploying.
Installation Notes
DAC cables have a strict reach limit — at 1.5 meters, this cable is suited for same-rack or adjacent-rack top-of-rack scenarios only. Exceeding the rated length is not possible with this passive cable; passive twinax does not amplify or retransmit. Ensure the QSFP28 host port supports breakout mode in firmware or the switch OS before cabling — not all QSFP28 ports support 4x25G breakout by default and may require explicit port-split configuration. No external power supply is required; the DAC draws operating power from the host transceiver cage.
