Network interface cards
A network card, network adapter or NIC (network interface) is part of computer hardware designed for computers to communicate through a computer network. It provides physical access to the network environment and often provides low-level addressing system through the use of MAC addresses.
Repeaters
Repeater receives a signal and a higher power as an obstacle to the other side it retransmits or degradation over long distances without the cover an electronic device, so that signal. In most twisted pair ethernet configurations, repeaters for long cable runs 100 meters is required.
Hubs
Hub contains multiple ports. When the package arrives at a port, it is copied unchanged to all ports hub for the transfer. Destination address in the box does not change the broadcast address.
Computer-network 