A printing apparatus connectable to a network, the printing apparatus comprising: a printing engine; and a transmitter-receiver to transmit packet data to an external device and to receive packet data from the external device via the network, the printing apparatus being operable in one of an active mode and a sleep mode during which less power is consumed than in the active mode, wherein: if no packet data is transmitted from the external device via the network for a predetermined period of time when the printing apparatus is in the active mode, the printing apparatus is arranged to transition to the sleep mode, if the packet data received via the transmitter-receiver from the network in the sleep mode is multicast packet data, respondent packet data is transmitted via the transmitter-receiver to the network without transitioning from the sleep mode to the active mode in response to the received multicast packet data, and if the packet data received via the transmitter-receiver from the network in the sleep mode is data to be printed, the printing apparatus is arranged to transition from the sleep mode to the active mode and the printing engine is arranged to perform a printing operation in the active mode. a printing engine; and a transmitter-receiver to transmit packet data to an external device and to receive packet data from the external device via the network, the printing apparatus being operable in one of an active mode and a sleep mode during which less power is consumed than in the active mode, wherein: if no packet data is transmitted from the external device via the network for a predetermined period of time when the printing apparatus is in the active mode, the printing apparatus is arranged to transition to the sleep mode, if the packet data received via the transmitter-receiver from the network in the sleep mode is multicast packet data, respondent packet data is transmitted via the transmitter-receiver to the network without transitioning from the sleep mode to the active mode in response to the received multicast packet data, and if the packet data received via the transmitter-receiver from the network in the sleep mode is data to be printed, the printing apparatus is arranged to transition from the sleep mode to the active mode and the printing engine is arranged to perform a printing operation in the active mode. if no packet data is transmitted from the external device via the network for a predetermined period of time when the printing apparatus is in the active mode, the printing apparatus is arranged to transition to the sleep mode, if the packet data received via the transmitter-receiver from the network in the sleep mode is multicast packet data, respondent packet data is transmitted via the transmitter-receiver to the network without transitioning from the sleep mode to the active mode in response to the received multicast packet data, and if the packet data received via the transmitter-receiver from the network in the sleep mode is data to be printed, the printing apparatus is arranged to transition from the sleep mode to the active mode and the printing engine is arranged to perform a printing operation in the active mode.