Kbase Article of the Week: About the 10 Gigabit Ethernet Port on Mac »

Apple Support:

The 10 Gigabit Ethernet (RJ-45) port is Nbase-T Ethernet technology that supports multiple data rates for speeds up to 10 Gbps over standard twisted pair copper cabling up to 100 meters (328 feet) in length. Depending on the device you’re connecting to, the cable type and technology used, and the cable length, the highest link speed is automatically negotiated. For example, if the device you’re connecting to is 10 Gbps-capable and the cable can support the speed, the two devices would negotiate the 10 Gbps speed.