Hi @achal ,
PHY address is determined by PHY address config pins on the PHY chip. Please refer to the EVK board.

MAC address is random in the demo. Officially it is allocated by IEEE (Institute of Electrical and Electronics Engineers), the last three bytes, the hexadecimal number AE-3C-40 represents the serial number of a certain network product (such as network card) manufactured by the manufacturer.
Regards,
Jing