[Kea-users] Why ISC KEA DHCP (DHCPv4) does not release an IP that has heen reserved and now released?

[Brian Candler]

On 17/12/2019 23:39, Eduardo Lúcio Amorim Costa wrote:
> I reserved an IP ("reservations") for a MAC ("hw-address"). That MAC 
> was removed from my subnet and the IP was reserved for another MAC. 
> That another MAC cannot "get" the IP that is now reserved for it and 
> ends up using an IP from "pool".
>
> What I can do to make the new machine (MAC) use this IP?

I suspect there is still a valid lease for the old MAC address with that 
IP address.  Kea doesn't rip it away: the new host will get an IP from 
pool until the old lease has expired.  For a full description of this 
scenario see:

https://kea.readthedocs.io/en/v1_6_0/arm/dhcp4-srv.html#conflicts-in-dhcpv4-reservations