Originally posted by Him
IPCONFIG /renew will give you a new IP.
dhcp does not have to give a new address when you renew.
When the lease expires, that IP address is returned to the pool and becomes available for reassignment to another client. When a client reboots, it checks to see if its lease is still valid. If so, it continues using the same IP address. If not, it requests a new IP address from the DHCP server. Servers and other computers that should always have the same IP address may be assigned a permanent IP address using a DHCP permanent lease.