The Lease Renewal Works process of DHCP

            When the DHCP lease 50 Percentage lease time, the client attempts Renewal. This process is performed automatically in the background. The computer may have Assigned the same IP address by DHCP Server for a long period of time, if they continuous operation without the need to shut down the network. 

            To renew the IP address lease, the client DHCPREQUEST broadcast message. That That IP address of the server sending the original lease DHCPACK message back to the client; it any new message contains parameters

Change, because in the creation of the original lease.

            If the DHCP client is unable to communicate with DHCP server, the client is waiting for the expiration of the lease time of 87.5 percentage points. If renewal Unsuccessful, which means that 100% of the lease time has expired, the client computer attempts and the default gateway configured to communicate. If the gateway does not respond, the client assumes that it is a new subnet and enter the Discovery phase, it attempts from any one IP configuration DHCP server.

          During startup of the client computer can also try to reconstruct the process or when the computer detects Innovation Network. This is because the client computer is offline when they move; For example, a laptop computer can insert a new subnet. If the contract is successful, the lease term It is reset. A new feature in Windows Server 2012 supported the role of DHCP, DHCP server failover protocol. This protocol allows the synchronization of information between the DHCP server and increase rental DHCP service availability. If a DHCP server is unavailable, another DHCP server continues Service clients on the same subnet.