|It would find it eventually. DNS records are not updated instantly, so in the time between the changing of the IP address, it is possible, in fact likely, that the old address would still be referenced. Functions that would require the DC would be sent to the old IP address and would fail, causing all sorts of issue.|
Also, that DNS information is replicated to all other DCs. Replication would fail because other DCs would be sending to the old IP address.
It would be a mess.