If an address conflict is detected, the address is removed from the pool and an administrator must resolve the conflict.
An address conflict occurs when two hosts use the same IP address. During address assignment, DHCP checks for conflicts using ping and gratuitous ARP. If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict.
(Reference: https://www.cisco.com/en/US/docs/ios/12_1/iproute/configuration/guide/1cddhcp.html)
