Communication device and communication system

A communication device in a communication system including a plurality of communication devices on a network, the plurality of communication devices each having a Dynamic Host Configuration Protocol (DHCP) server function of allocating an Internet Protocol (IP) address, the communication device comprising:

• a communicator that transmits a confirmation signal for confirming presence or absence of an other communication device having the DHCP server function started on the network;
• and
• a controller that controls the DHCP server function,
• wherein the controller:
• transmits a first confirmation signal to the other communication device through the communicator;
• starts the DHCP server function and transmits a second confirmation signal to the other communication device through the communicator when a first response signal is not received from the other communication device in response to the first confirmation signal;
• stops the DHCP server function when a second response signal is received in response to the second confirmation signal;
• and
• performs a transmission control of a third confirmation signal to the other communication device through the communicator, based on the second response signal.