SFP+ to SFP+ DAC is the direct attach twinax copper cable that connects a SFP+ on one terminal end and another SFP+ on the other end. It provides input and output of 10G Ethernet through the SFP+ small form factor. SFP+ to SFP+ DAC can be categorized into passive SFP+ to SFP+ DAC and active DAC. The passive copper uses straight wire which does not consume power and usually used in short distance up to 12m, while the active copper uses power-consuming electronic components which is lighter and thinner with a limitation distance from 15 to 20m.
QSFP+ to QSFP+ DAC is a type of direct attach twinax copper cable that links two QSFP+ transceiver modules on each terminal end which eliminates the connector. QSFP+ to QSFP+ DAC operates in 40G Ethernet by using the quad small-form factor pluggable plus with integrated duplex serial data links for bidirectional communication. There are classifications of passive QSFP+ to QSFP+ DAC and active QSFP+ to QSFP+ DAC. The former is cheaper but not includes electronic components, while the latter is more expensive but possesses electronic components with higher performance.
QSFP+ to 4 SFP+ DAC is the direct attach twinax copper cable which has one QSFP+ module on one end and four SFP+ modules on the other end. It is designed to be applied in 40 Gigabit Ethernet. The port with a QSFP+ is available to provide the data rate of 40Gbps, and the port with four SFP+ is able to reach the rate of 10Gbps for each module. This type of DAC enables the cable to reach more than one device at the terminal end, which is more effective and useful for multiple devices performing at the same time. And it has two sorts of passive QSFP+ to 4 SFP+ DAC and active QSFP+ to 4 SFP+ DAC.
SFP+ to SFP+ AOC is the active optical cable that attaches two SFP+ transceivers to each end. It is used for 10G Ethernet transmission for a much longer distance than direct attach copper cable which can reach up to 100 meters. The material of AOC is made of optic fiber to convey electronics and optics. This makes SFP+ to SFP+ AOC have a higher performance and lower power consumption. Since the SFP+ to SFP+ AOC is always active, it has no other classifications.
QSFP+ to QSFP+ AOC is the active optical cable which connects an QSFP+ transceiver on one end and a QSFP+ transceiver on the other end. QSFP+ to QSFP+ AOC can reach a wider bandwidth of 40G in Ethernet which enables a faster transmitting speed. The connected distance is limited up to 100m which is longer than DAC products. QSFP+ to QSFP+ AOC transmits electronic and optical data via optic fiber which provides a better functionality, and it is keeping to be active all the time.
QSFP+ to 4 SFP+ AOC is the active optical cable, one of its terminal end is linked to an QSFP+ module and the other end is linked to four different SFP+ modules. It is applied in the 40G Ethernet with a higher transmission speed than 10G products. The QSFP+ to 4 SFP+ AOC can be connected to more than one device which greatly improved the effectiveness of devices. With the development of AOC, it is now acting as the replacement of DAC for a higer performance with optic fiber.