Patent ID: 8713136

Claim:
A method of allocating an IP address of an image forming apparatus using Dynamic Host Configuration Protocol (DHCP), comprising: requesting a DHCP server to allocate an IP address to an image forming apparatus having a previously allocated IP address wherein the requesting is performed by the image forming apparatus, in response to the image forming apparatus being re-connected to a network; responding to the IP address allocation request wherein the responding is performed by the DHCP server; checking an IP allocation mode set for the image forming apparatus; determining, by the image forming apparatus, whether to respond to the response of the DHCP server according to the checked IP allocation mode; and providing, by the DHCP server, the previously allocated IP address to the image forming apparatus when a response is not received from the image forming apparatus in a predetermined time, or a new IP address to the image forming apparatus when a response is received from the image forming apparatus.