Full Duplex (FDX) is a type of communication system. In full duplex, there is a two-way communication between the sender and the receiver.

A firewall is a network security system that prevents unauthorized users from having access to a network.

Frequency is defined as the number of cycles per unit time. Frequency is usually used to represent short and fast waves like sound and radio signals.

Frequency Division Duplex (FDD) is a duplex communication technique in which connected parties transmit at different frequencies for upstream and downstream communication.