7. What types of transmission media are used in client/server networks? In addition to wireless media, three main cable types are used: twisted pair cable, coaxial cable, and fiber-optic cable. Twisted pair cable consists of four pairs of wires twisted around each other to reduce interference. Coaxial cable is the same type of cable used by your cable TV company to run a signal into your house. It provides better shielding from interference than twisted pair cable but is more expensive. Fiber-optic cable uses glass or plastic bundles of fiber to send signals using light waves. It provides the largest bandwidth, but is expensive and difficult to install. Wireless media utilizes radio waves to send data between nodes on a network.
8. What software needs to be running on computers attached to a client/server network, and how does this software control network communications? Network operating system (NOS) software needs to be installed on each computer and server connected to a client/server network to provide the services necessary for the devices to communicate. The NOS provides a set of common rules (called a protocol) that controls communication between devices on the network.
9. How do network adapters enable computers to participate in a client/server network? Network adapters provide three critical functions: (1) They take low-power data signals generated by the computer and convert them into higher-powered signals that can traverse network media easily. (2) They break the data generated by the computer into packets and package them for transmission across the network media. (3) They act as gatekeepers to control the flow of data to and from the computer. Without a network adapter, a computer could not communicate on a network.
10. What devices assist in moving data around a client/server network? Repeaters are used to amplify signals on a network ensuring that signals are received even at the end of a long cable run. Hubs receive and retransmit signals to all devices attached to them. Switches are “smart” hubs in that they can read the address of data packets and retransmit a signal to its destination instead of to every device connected to the switch. Routers are used to route data between two different networks such as between a corporate network and the Internet.
11. What measures are employed to keep large networks secure? Access to most networks requires authentication procedures (such as entering a user ID and password) to ensure that only authorized users access the network. The system administrator defines access privileges for users so that they can access only specific files. Network equipment is physically secured behind locked doors, which are often protected by biometric access devices. Biometric devices, such as fingerprint and palm readers, use unique physical characteristics of individuals for identification purposes. Firewalls are also employed to keep hackers from attacking networks through Internet connections. Packet screeners review traffic going to and from the network to ascertain whether it was generated by a legitimate user.