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Part III
Check yourself
I. a) True or false? Read the sentences and give your arguments for and against.
1. Wireless Internet service providers (WISPs) provide connection speeds more than 30 times faster than dial-up connections from 384 Kbps to2.0 Mbps.
2. Connecting to the Internet requires special devices typically a cable or DSL modem linked to a computerusing an Ethernet cable.
3. Establishing and maintaining computer security is necessary to keep hardware, software, and data safe from harm or destruction.
4. The best way to protect data is to effectively control access to it.
5. Users may need a password to log onto a computer system or to specific parts of it.
6. A network is a group of two or more computers linked together.
7. A telephone network is similar in makes up to a computer network. The Public Switched Telephone Network (PSTN) supports telephone service, and it is the worlds largest collection of interconnected commercial and government- owned voice-oriented systems.
8. You can use a network for information sharing, hardware sharing, software sharing, and as a collaborative environment.
9. Networks are categorized according to size as local area networks (LANs) and wide area networks (WANs).
10. LANs connect personal computers, workstations, and other devices such as printers and scanners in a limited geographical area, such as a office building, a school, or a home.
11. A WAN is made up of several connected local area networks.
12. In a client/server network, one or more computers on the network acts as a server. The server manages network resources.
13. In a peer-to-peer (P2P) network, all of the computers are equal. No computer is designated as the server. People on the network each determine what files on their computer they share with others on the network.
14. Data insecurity is a risk with many networks.
15. Some risks to computers are natural causes, some are accidents, and others are intentional.
16. The biggest network is the Internet.
17. E-mail always is private.
18. A WAN covers a large geographical area.
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19. The best way to protect data is to effectively control access to it.
20. Networks are classified according to speed.
21. Communication languages used by computer devices are called network protocol.
22. Yet another way to classify computer networks is by the set of protocols they support.
23. Networks often implement multiple protocols with each supporting specific applications.
24. Popular protocols include TCP/IP, the most common protocol found on the Internet and in home networks.
b) Multiple Choice. Select the best response for the following statements:
1. A telephone network is similar in make up to a ___________ network.
a. Computer network b. Local area network c. Tiny area network d. Metropolitan area network
2. A ____________ server acts as an intermediary between a user and the Internet.
a. High-level b. Proxy c. Connected-level d. Biometric
3. The two broad categories of network architecture are _______ and peer-to-peer.
a. Intranet/extranet b. DSL c. Client/server d. Proxy/server
4. A(n) _____________ can carry both data and voice.
a. SLD b. Bridge c. WAN d. DSL
5. A ________________ is a variation of the LAN that use nophysical wires.
a. WLAN b. PSTN c. P2P d. WiMAX
Additional information
Understand Network communications Most networks consist of a network server and computer clients.In addition, networks use two other categories of hardware:communications devices and devices that connect the networkcabling and amplify the signal. Communication hardware devices help to transmit and receive data. When we think about communication hardware, the first thing that generally comes to mind is the desktop computer and router. However, other types of computers and devices send and receive data. Some examples are mainframe computers, minicomputers, and large computers such as supercomputers; handheld and laptop computers; and even fax machines and digital cameras. All of these devices require some type of transmitting hardware device
Modem is an acronym for modulated-demodulate, which means tocovert analog signals to digital and vice versa. This device enables a computer to transmit data over telephone lines.Computer information is stored digitally (in binary code of 0sand 1s), where as information sent over telephone lines orother media generally is transmitted in the form of analog waves. Both the sending and receiving users must have a modem. The speed at which modems can transmit data has increased dramatically in the past few decades. The first modems introduced in the 1960s could send data at a rate of about 300 bits per second (bps). By the early 1990s, the speed of data transmission via modem had increased to 9600bps, with the standard modem speed of 56 Kbps (kilobits persecond) reached by the middle of the decade. Special modems can transmit data as fast as 8 Mbps (megabits per second) over telephone lines.
Cable Modem uses coaxial cable to send and receive data. This is the same type of cable used for cable TV. The band width, which determines the amount of data that can be sent at one-time, is much greater with a cable modem than with the other technology of dial-up modem. For this reason, cable modems are used to deliver broad band Internet access, which is a high data rate connection to the Internet. Cable modems allow as many as 1,000 users to transmit data onone 6-MHz (megahertz) channel and can transmit data atspeeds of 30 to 40 Mbps. A cable modem can be connected directly to your computer, enabling you to connect to the Internet, or it can be connected to a router so that your computer has wireless access to the Internet.
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Digital Subscriber Line (DSL). DSL is an Internet connection technology that provides for the transfer of information to a computer at a high-speed band width over ordinary copper telephone lines. A DSL can carry both data and voice. The data part of the line is a dedicated connection to the Internet. High bit-rate DSL (HDSL) was the first DSL technology to use twisted-pair cables. Very-high bit-rate DSL (VDSL) can support HDTV, telephone services, and Internet access over a single connection. Like cable modems, DSLmodems are widely used to provide broadband Internet accesss
T-1 Line. T-1 line is a type of fiber-optic telephone line that can transmit up to 1.544 megabits per second or can be used to transmit 25digitized voice channels. T-1 lines can be used for data transferon a network or to provide phone service for a commercial building.
Wireless. Wireless Internet service providers (WISPs) provide connection speedsmore than 30 times faster than dial-up connections from 384 Kbps to2.0 Mbps. WiMAX (Worldwide Interoperability for Microwave Access) is a wireless technology that can deliver maximum speeds of up to 1 Gbps to your cell phone, home computer, or car. WiMAX is an alternative to cable and DSL, especially for users in areas that cable and DSL service providers do not serve. It is also used to connect mobile computer users to the Internet acrosscities and countries. You can use WiMAX USB modem to connect toWiMAX network.
Connecting to the Internet. As indicated earlier, connecting to the Internet requires special devices typically a cable or DSL modem linked to a computer using an Ethernet cable, a type of cable designed to connect devices on a network.
Wirelessly connect to Internet A notebook computer or other type of device such as acomputer game system an iPhone or other smart phone, orsimilar devicesAn internal wireless adapter or a USB port for connecting anexternal adapter; the adapter must be compatible with thewireless providers protocolsA high-speed, wireless Internet access plan from a providerSniffer software, used to locate hot spots: usually build intothe device
