How to allocate an address to a specific host

[Chiu, PCM (Peter)]

I have a query about allocating address to a group of specific hosts
but no one else.

Below is our current set up.

Not sure why hosts other than those in the list are also served with 
this set up.

Can anyone spot anything?  Thanks.
========================================================================
===
option domain-name              "ncas.ac.uk";
option domain-name-servers      82.66.188.240;
option subnet-mask              255.255.252.0;
ddns-update-style ad-hoc;
subnet 82.66.191.0 netmask 255.255.255.0 {
range 82.66.191.0 82.66.191.200; 
  option routers 82.66.188.254;
}
	group {
#Insert local ip here \/
  	next-server 82.66.191.187;          # name of your TFTP server
  	filename "pxelinux.0";        # name of the bootloader program
	
	host n0.ral1 {
		hardware ethernet 00:E0:81:34:0A:4A;
		fixed-address 82.66.191.187;
	}
	host raltes1 {
                hardware ethernet 00:E0:81:34:92:18;
                fixed-address 82.66.191.50;
        }
	host raltes2 {
                hardware ethernet 00:E0:81:2F:22:BA;
                fixed-address 82.66.191.51;
        }
	host raltes3 {
                hardware ethernet 00:E0:81:34:0F:B8;
                fixed-address 82.66.191.52;
        }
	host raltes4 {
                hardware ethernet 00:E0:81:34:8D:4C;
                fixed-address 82.66.191.53;
        }
        host raltes5 {
                hardware ethernet 00:E0:81:34:92:62;
                fixed-address 82.66.191.54;
        }
        host raltes6 {
                hardware ethernet 00:E0:81:34:9B:B0;
                fixed-address 82.66.191.55;
        }
}