How to make dhcpd send NAKs instead of silently ignoring DHCPREQUESTS?

Simon Hobson dhcp1 at
Wed Apr 4 07:00:21 UTC 2012

Andre Albsmeier wrote:

>Yes, sure. I just _thought_ that if I am responsible for, let's
>say, subnet I should be able to control this

I think this used to be possible in earlier versions, but we used to 
get people coming here on a semi regular basis who were using a 
Windows Server* approach and couldn't understand why they were 
getting duplicate leases (dynamic leases for addresses "reserved" for 
fixed address hosts).

I know at some point a warning was added, so if there were overlaps 
then a warning would be spat out during startup, but I wasn't aware 
that the more specific warning/error you've seen had been added - but 
then I'm no longer a heavy user of this code, and I don't have such 
overlaps in my config.

* Don't know if you've used it, but (from memory) on Windows the 
admin is very very different. You can't modify a scope once created, 
so it's custom to create a scope that covers the entire subnet. You 
then "block out" ranges you don't want included, and reserve leases 
for specific clients. So more or less the opposite of how you 
configure the ISC server.

Simon Hobson

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