Best practice on removing IP Scopes(subnets)

[Glenn Satchell]

>To: Users of ISC DHCP <dhcp-users at lists.isc.org>
>Subject: Re: Best practice on removing IP Scopes(subnets) 
>Date: Fri, 24 Apr 2009 11:54:35 CDT
>From: John Hascall <john at iastate.edu>
>
>Christof Chen writes:
>> I just want to mention there is a fairly recent addition to DHCPD:
>>     deny after TIME;
>> in a pool shortens the lease duration automatically as TIME approaches.
>> Together with a corresponding
>>     allow after TIME;
>> in a different pool this allows for a nearly automatic switchover at a
>> preconfigured time.
>
>That's pretty swell, but what would really be awesome is
>something which would allow renews, but not new offers
>in a pool!
>
>Maybe allowing "deny booting" in pool scope could do that.
>
>Then you could very nicely switch from one pool to another.
>
>John

Note this is untested by me, but in theory something like this
in the pool, or subnet might do this:

# 1 = DHCPDISCOVER
if option dhcp-message-type = 1 {
	deny booting;
}

regards,
-glenn