What is a network protocal?
a set of rules that govern communication in the network.
What is a virtual private network? Why is it called virtual?
A virtual private network (VPN) is practically part of the Internet, but special software protects sites from unauthorized access.

This gives the feeling that the organization uses a private network.

Explain the notions of WAN, LAN, MAN, and PAN
A WAN is a network that serves a large area, usually national or global. A LAN serves an office, a campus, or a household. A MAN serves a metropolitan area. (WiMAX is intended to support MANs.

) A PAN is a digital network that supports an individual. Bluetooth serves this purpose.

What is the difference between circut switching and packet switching
In circuit switching (used for telephoning), a certain path in the network is devoted for communication between the parties for the duration of the communication session. All communication (voice or data) occurs in this path, called a circuit.

In packet switching, each packet of several bits may be transmitted in another path to the destination. Frame relay is a packet switching standard of variable packet size. TCP/IP works with packet switching.

What are technical advantages of optical fibers over other communications media?
Optical fibers support greater speed (bit rate), are not prone to EMI and RFI, and need fewer repeaters for long distances than other media.