broadcast
termnetworking
One-to-all delivery inside a network segment: a frame or packet addressed so that every host must receive and process it.
On Ethernet the destination FF:FF:FF:FF:FF:FF reaches every station in the segment; in IPv4, Jon Mogul's RFC 919 (October 1984) set the conventions, 255.255.255.255 as the limited broadcast that routers never forward, and the highest address of each subnet as its directed broadcast. ARP's who-has question rides on it, as does DHCP discovery, which is why a host with no address at all can still ask for one. Because routers stop broadcasts, the broadcast domain ends where the router begins, and that boundary is most of the reason subnets and VLANs exist. IPv6 dropped broadcast entirely and does everything with multicast groups instead.