DHCP Client Behavior after Reboot

If the DHCP client device reboots with a previously obtained IP address, the DHCP client sends the DHCP request packet, which is a subnet-directed broadcast packet from all the operationally up ports of the device. Once the DHCP server responds positively to the request, the previously obtained IP address is leased seamlessly. If the DHCP server responds in the negative, the previously obtained IP address will be released, and the DHCP process restarts.

If the software version is Layer 3, when the DHCP client comes up after a reboot with a previously obtained IP address, the DHCP client sends the DHCP request packets only on the ports where the DHCP client was enabled previously on the device.