All the advice about DHCP and PXEClient tells you about the ability to configure based on the client’s vendor-class-identifier string, but nowhere tells you how to find out the contents of this magical string. In fact it couldn’t really be easier, as the following instructions explain:

Step 1 - Update DHCP Server

Simply modify /etc/dhcp3/dhcpd.conf on your DHCP server and add the following somewhere near the top:

# So that the vendor-class-identifier shows in dhcpd.leases file
set vendor-string = option vendor-class-identifier;

Step 2 - Restart your DHCP server

# /etc/init.d/dhcp3-server restart

Step 3 - Test Boot a Client

Then boot a client and look at the contents of the /var/lib/dhcp3/dhcpd.leases file, you should find entries like this:

lease 192.168.0.174 {
    starts 2 2009/04/14 07:40:21;
    ends 2 2009/04/14 13:40:21;
    binding state active;
    next binding state free;
    hardware ethernet 00:fb:3d:5f:fg:7e;
    set vendor-string = "PXEClient:Arch:00000:UNDI:002001";
}