A Lease time, is the lease duration. A client acquires a lease for a network address for a fixed period of time. Throughout the protocol, times are to be represented in units of seconds.
On receiving a DHCP request, the DHCP server may respond with specific information for each client, as previously configured by an administrator, or with a specific address and any other information valid for the entire network and for the time period(Lease time) for which the allocation (lease) is valid.
A client MAY choose to renew or extend its lease prior to half of the Lease time. If a client does not extend its lease in the Lease time, A DHCP server sets the IP address as "Expired" and may allocate the same IP address to another.