MAC addresses of our physical NICs on ESX hosts

I have been asked a very interesting question.   What is the MAC address for each of the physical NICs inside our ESX host.   Our ESX3.5Update4 host has 6 of them.

I am able to use ESXCfg to identify the vnics but does equate to the physical nics?   or, how do I locate the MAC address of the physical nics????