In the strength of the carrier signal is varied to represent binary 1 or 0. (72) is a system that can map a name to an address and conversely an address to an name. (73) is a three-way handshaking authentication protocol that it's packets are encapsulated in the point-to-point protocol (74) is an approach that enables an ATM Switch to behave like a LAN switch. (75) is an guided media which is made of glass or plastic and transmits signals in the form. of light.