Patent ID: 8755307

Claim:
An IP-address distribution device comprising: a path-information obtaining unit that obtains a piece of path information indicating a physical connection configuration of a communication network that reaches a terminal as a request source of an IP address; and an IP-address specifying unit that specifies an IP address to be distributed to the request source based on a piece of path information of the communication network; and an IP-address correspondence table in which correspondence relationships between pieces of path information of the communication network and IP addresses are registered, wherein the path-information obtaining unit obtains the path information by inquiring a port number of an Ethernet switch that has transmitted a MAC address of the request source, and the IP-address specifying unit, when specifying an IP address corresponding to the path information of the communication network based on a result of referring to the IP-address correspondence table, specifies and distributes a second IP address as a response to an IP address request from a second terminal, wherein the second IP address is different from a first IP address of a first terminal to which the first IP address is already distributed, the first terminal having been connected to the IP-address distribution device via a specific path, the second terminal is connected to the specific path with respect to a path from the second terminal to the IP-address distribution device, and the second terminal has a MAC address different from a MAC address of the first terminal to which the first IP address is already distributed.