During the autonegotiation process, network devices communicate and determine the highest mutually supported data rate. In the case of a network adapter supporting both 10 Gigabit per second (10Gb/s) and 1 Gigabit per second (1 Gb/s), the negotiation will typically select the highest possible speed that both devices support.
If the network adapter supports 10Gb/s and the connected device also supports 10Gb/s, and the cable quality and length are suitable for that data rate, the autonegotiation will likely result in a 10Gb/s connection.
However, if there are factors such as excessive cable length or poor cable quality that prevent reliable communication at 10Gb/s, could it be possible that the negotiation succeeds but the transmission rate is lower, for instance 8Gb/s?
Or in case the above factors occur, the network adapter will inevitably renegotiate with the connected device and agree upon a lower speed, such as 1Gb/s, that can be reliably supported over the given cable conditions?