Thanks but i have noticed that this only applies to IPv6 and not to IPv4, is that right ?
If it is windows 2008 go to the Microsoft library:
After you enable it, you will find event logs for the following:
ID: A DHCP server event ID code.
Date: The logged on entry date on the DHCP server.
Time: The log in time for the entry on the DHCP server.
Description: A description of this DHCP server event.
IP Address: The IP address of the DHCP client.
Host Name: The host name of the DHCP client.
MAC Address: The media access control (MAC) address used by the network adapter hardware of the client.