Comment 2 for bug 1288923

There was never a guarantee that moving the DHCP server from one network host to another would result in getting the same IP address. For example, if an agent's host failed and the agent went away without warning, it would not have the opportunity to release its DHCP port and a new agent -- presumably started by some HA setup -- would not be able to pick it up.

With that said, it used to be more likely that an intentional move of the DHCP server to another host would preserve the IP address . That was when IP addresses were returned to to the availability pool immediately rather than waiting for the pool to be exhausted. It was this change that made this scenario more likely to happen.