In a Ethernet local area network (LAN), promiscuous mode is a mode of operation in which every data packet transmitted is received and read by every network adapter. Promiscuous mode must be supported by each network adapter as well as by the input/output driver in the host operating system. Promiscuous mode is often used to monitor network activity. Promiscuous mode is the opposite of non-promiscuous mode. When a data packet is transmitted in non-promiscuous mode, all the LAN devices "hear" the data to determine if the network address included in the data packet is theirs. If it isn't, the data packet is passed onto the next LAN device until the device with the correct network address is reached. That device then receives and reads the data.