Microsoft has developed or added some security to DHCP Server by means of CLASS ID. You can use Class ID to secure a network for client who is part of the network or laptop users who receive their IP Address from this DHCP Server on the network. In DHCP Server you can configure the Class ID. When you configure Class ID you need to use the Same ID on all client machines so any DHCP Packet sent by the client can be understood by the DHCP server of that class. You set Class ID on client machines using *Ipconfig /setclassid* command.