DHCP states
Boots => INITIALIZE state
DHCPDISCOVER: broadcast request to servers => SELECT state
DHCPOFFER (from server) => remain in SELECT
DHCPREQUEST => select one of the offers and notify server (goto REQUEST state) about the lease
DHCPACK => server Oks request to lease => go to the BOUND state
Renewal: after 50% of lease go to RENEW state
Rebind: after 87.5% of time, if server has not responded, try again and go to REBIND.
If server NACKs or lease expires, or client sends DCHPRELEASE, go to INITIALIZE, else come back to BOUND state