What is broadcasting and Name a network connection device that relies on it and one that does not rely on it?

Broadcasting is when a packet is sent to all hosts, or all hosts on a subnet. When a broadcast packet is sent through a typical ethernet switch, all port lights will flicker as that packet is forwarded out every port. Other packets are inspected for their intended destination and then forwarded out the correct port.

Two very necessary and prevalent protocols, DHCP and ARP, rely on broadcasting. This means a typical ethernet router/gateway device relies on broadcasts. A device that does not rely on broadcasts is an ethernet NIC.