After running cmd, you can check the MAC (Physical Address) address by using the command ipconfig /all.
assuming that by down you mean get... ipconfig if you want all ip settings then ipconfig /all command ipconfig If you mean to disable or turn off the ip to disconnect from the internet then ipconfig /release
Ipconfig shows IP address, Subnet Mask, and Default gateway for all adapters. Ipconfig /all shows the description of each network connection along with additional information such as your physical (MAC) address, DHCP connections, Lease times, as well as in-depth IPv6 information.
click start search for: cmd hit enter type in ipconfig /all Under Physical address that is your MAC address
ipconfig /release
host name physical address Lease Obtained Lease Expires
XP and Vista: WindowsKey+R type cmd type ipconfig/all at the command prompt look under physical address
ipconfig /release ipconfig /renew
ipconfig /release
ipconfig /release ipconfig /renew
ipconfig
From a command prompt type: ipconfig /all It will list the adapter's Ethernet address as "Physical Address". It will be 6 pairs of hex values with dashes in between.