DHCP does not issue or respond to a MAC address. It receives a broadcast from a client that basically says, "This is my MAC address, may I please have an IP address?" The way to prevent this is to disable the clients ability to request an IP address.
The answer is: 1. statically assign an IP address -- by doing this you turn off the client pc from making a request. 2. Since you statically assigned the ip address a. make sure that it is not in you DHCP pool of addresses or b. reserve the ipto the corresponding MAC Address or c. just remove that ip address from pool after statically assigning it.
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Exclude MAC from DHCP