How to allocate an address to a specific host

[Chiu, PCM (Peter)]

Thanks Simon,

Very clear explanation.   

Peter 

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
Behalf Of Simon Hobson
Sent: 13 March 2006 14:45
To: dhcp-users at isc.org
Subject: Re: How to allocate an address to a specific host

Chiu, PCM (Peter) wrote:
>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.

Because the config says to !


>=======================================================================
>=
>===
>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;
>         }
>}

You have several errors here :

1) "range 82.66.191.0 82.66.191.200" is not valid as 82.66.191.0 is not
a valid host address for the subnet.

2) You have fixed address statements with addresses within the dynamic
range. The server does NOT automatically deal with this - it is for the
administrator to make them mutually exclusive.

3) If all you want to do is serve up the fixed addresses, then omit the
range statement - as it stands, you have told it to give certain clients
fixed addresses, and anything else a dynamic address.

Simon