DHCP server and Duplicate Address Detection (DAD)

Hello,
I have a question regarding Duplicate Address Detection (DAD) and
DHCP server on linux:
Suppose the DHCP server will try to assign , when a lease expiters, an
IP
address which is already held by a differnet machine.
What then ? will the DHCP server succeed with that ? does it try to
send
a gartutious ARP in such a case (from "0.0.0.0") and fails with
assigning an already assigned address ? is it configurable ?

I am the very popular dhcp serve (commmon in most distros) from isc,
which is in http://isc.org/products/DHCP/

I tried to find out about this in the docs and in the code, but could
not
find anything.

Regards,
Mark