How to restrict Windows XP DHCP clients to a specific subnet?

[Ole Holm Nielsen]

Simon Hobson dhcp1 at thehobsons.co.uk wrote:
> You define a class that matches the group of machines - in this case XP clients.
>
> Use "allow members of ..." and "deny members of ..." to control which subnets the machines are allowed to get leases in. I suspect your problem (guessing since "it didn't work" isn't very descriptive of what you've tried) is that you have not denied the class from other subnets. Specifically, just because you have a subnet (or more correctly, a pool in a subnet) that has 'allow members of "foo"', that does not prevent members of "foo" getting leases in other subnets.

Sounds logical, but how do I define the classes of machines?  Mind you, 
I have a whole lot of client definitions like:

host camd-T61-25    { hardware ethernet 00:1A:6B:36:34:15; }

which need to be joined into some class.

Thanks,
Ole

-- 
Ole Holm Nielsen
Department of Physics, Technical University of Denmark