Which specification for connectivity is currently used in data centers for lower cost and simplicity?

10GBase-CX is commonly used in data centers. It is referred to by its nickname of Twinax. It is a fixed, balanced coaxial pair that can be run up to 25 meters. 10GBase-T is usually category 6 cable that is nominally run up to 55 meters in length to achieve 10 Gb/s speeds. 40GBase-T is usually category 8 cable that is nominally run up to 30 meters to provide 40 Gb/s speeds. 100GBase-TX is not a valid specification for Ethernet connectivity. 100Base-TX is standard 100 Mb/s connectivity that supports full-duplex communications.