Category 4 UTP cable can only transfer up to 16 Mbps. Category 5 UTP cable can transmit up to the specified 100 Mbps. DNS names use periods to separate domain and sub-domain names. A, B - A firewall opens the necessary ports to internal host computers, and password security will deter a hacker from easily gaining access. B - Repeaters strengthen baseband signals.
Amplifiers boost signal strength on broadband networks.
Multiplexers are devices that allow sharing single medium segments by combining several channels for outgoing transmissions over a segment and reverse the process for incoming signals. They use neither signal processing nor regeneration. A time domain reflectometer is a cable testing tool, not a signal boosting technology. No centralized control is involved. With demand priority, communications only occur between a sending computer, the hub, and a receiving computer, where all transmissions are under the hub's control.