If you mean the MAC address, that's a layer-2 concept.
The NIC operates on Layer 2 (Data Link Layer) of the OSI Model.
Network layer
generally layer 4, but SOCKS operates at layer 5, which allows it to work well with applications
Application gateway/proxy
A NIC operates at those two layers.
MAC sublayer is located at Data link layer.
MAC layer by OSI model is also known as
TCP operates at Layer 4 which is Transport of the OSI Model!
Layer 1 of the OSI Layer Model does not support MAC addresses.
The MAC address would place it at the data link layer of the OSI model.
transport layer
FTP operates in application layer of ISO OSI layered model.