StarTech.com Juniper QFX-QSFP-DAC-1M Compatible 1m 40G QSFP+ to QSFP+ Direct Attach Cable Twinax - 40GbE QSFP+ Copper DAC 40 Gbps Low Power Passive Transceiver Module DAC

Product Overview

AI-generated summary

For £21 ex-VAT, this is the kind of “get it working” DAC you buy when you already know you’re doing short-reach 40GbE and you don’t want to pay for optics. The passive twinax approach means low fuss, quick install, and typically fewer moving parts to go wrong than with active optics—great for patching between top-of-rack switches, within the same rack, or any setup where 1m is realistic. If you’re building a lab, doing break/fix, or topping up a bunch of spares for a datacentre-friendly environment, it’s genuinely good value.

That said, I wouldn’t buy it if you need flexibility beyond a rack run, or if you’re not confident your switch will like the optics/copper DAC pairing. DAC compatibility can be picky depending on vendor/port expectations, and passive cables tend to be more “distance strict” than active solutions. Also, if you’re chasing best-in-class signal quality for marginal links or longer runs, spend a bit more on something engineered for your exact scenario. In short: buy it if your use-case is 40GbE over very short distances and you want cost control; skip it if you need guaranteed broad interoperability or you’re anywhere near the edge of the expected cable length.