100G QSFP28 to 4x25G SFP28 Breakout DAC Cable - 1M Passive Twinax

In this review the focus is on a practical, rack-level connectivity tool: a 1-meter passive breakout DAC that converts a single 100G QSFP28 port into four 25G SFP28 ports. The bottom line is that this cable is for engineers and data center operators who need a low-cost, short-reach solution for high-density switching and server interconnects; the single biggest reason to buy is straightforward compatibility with Cisco QSFP-4SFP25G-CU1M style ports and factory signal validation that reduces integration hassle.

Key Features

• 100Gb/s breakout: Converts a single QSFP28 port into four independent 25G SFP28 links for flexible aggregation and server connectivity.
• Passive twinax construction: Offers a cost-effective, low-power option for very short links within racks and across adjacent racks.
• 1-meter length: The 1 m (3.3 ft) reach is ideal for top-of-rack and adjacent-rack connections without excess cabling clutter.
• 30 AWG cable: Thin twinax conductors help minimize bulk and allow neat routing in dense cable environments.
• Compatibility testing: Each cable is individually tested on switches in a lab environment and passes TDR and VNA validation for signal integrity.
• Manufacturer support: Supplied by a direct attach cable manufacturer who offers customization and understands DAC requirements.

Who It's For

This breakout cable suits network engineers, data center operators, and systems integrators who need a reliable short-reach connection between 100G QSFP ports and multiple 25G SFP ports on switches, servers, or NICs. It is particularly useful for consolidating links when migrating server ports to higher density switch fabrics.

Those who need long-reach optics, hot-pluggable active cables, or fiber-based connections should look elsewhere; this passive twinax is intended for short intra-rack connections and is not a replacement for fiber over longer distances or where electrical isolation is required.

Pros & Cons

Pros

• Cost-effective passive design for short links that reduces power and complexity compared with active optics.
• Clear compatibility with Cisco-style QSFP-4SFP25G-CU1M ports and positive customer reports on interoperability with other vendors.
• Individually tested in a signal integrity lab with TDR and VNA verification, lowering the risk of link issues on deployment.
• Compact 30 AWG twinax enables neat routing in dense rack environments.

Cons

• Limited to very short distances; the 1 m length and passive nature make it unsuitable for longer, cross-room links.
• No hot-swap electrical amplification since the cable is passive, which can limit margin in noisy or marginal port conditions.

Specifications

Data Rate	100 Gb/s
Form Factor	QSFP28 to 4 x SFP28
Length	1 meter (3.3 ft)
Cable Gauge	30 AWG
Type	Passive Direct Attach Copper Twinax
Compatibility	Compatible with Cisco QSFP-4SFP25G-CU1M style ports
Operating Temp	Standard 0 to 70 C; Industrial -20 to 80 C

Our Verdict

The 1-meter QSFP28 to 4x25G SFP28 passive DAC is a solid value for data center racks that need short, cost-conscious breakout links. Network teams seeking simple, proven compatibility and low-power connections will appreciate the lab testing and individual switch validation, while those needing longer reach or active amplification should choose a different solution.

Frequently Asked Questions

Will this cable work with Cisco QSFP-4SFP25G-CU1M ports?
Yes, the cable is designed to be fully compatible with Cisco QSFP-4SFP25G-CU1M style QSFP28 ports and is tested for interoperability.

Is this cable suitable for connections longer than 1 meter?
No, this passive twinax is intended for very short links; for longer distances use fiber or active solutions.

Does the cable require configuration or special firmware?
No special configuration is required; it is a passive direct attach cable and operates as a plug-and-play electrical connection when inserted into supported ports.