A communication apparatus includes a plurality of network connection units connected to a network. The communication apparatus (a) notifies an external device of a plurality of IP addresses assigned respectively to the plurality of network connection units so that the external device can select one of the plurality of IP addresses, and (b) releases the plurality of IP addresses except an IP address selected by the external device so that the communication apparatus can provide a service to the external device via the network using the IP address selected by the external device.