VISUAL SUMMARY Communications and Networks

Home , Hotspot (Wi-Fi), Personal area network

Rev.Confirming Pages

COMMUNICATIONS COMMUNICATION CHANNELS

Communications is the process of sharing data, pro- Communication channels carry data from one com- grams, and information between two or more computer to another. puters. Applications include e-mail, texting, Internet telephones, and electronic commerce. Physical Connections Physical connections use a solid medium to connect Connectivity sending and receiving devices. Connections include Connectivity is a concept related to using computer twisted pair (telephone lines and Ethernet cables), networks to link people and resources. You can link or coaxial cable, and fiber-optic cable. connect to large computers and the Internet, provid- Wireless Connections ing access to extensive information resources. Wireless connections do not use a solid substance to The Wireless Revolution connect devices. Most use radio waves. Mobile devices like smartphones and tablets have • Bluetooth— transmits data over short distances; brought dramatic changes in connectivity and com- widely used for wireless headsets, printers, and munications. These wireless devices are becoming handheld devices. widely used for computer communication. • Wi-Fi (wireless fidelity)— uses high-frequency radio signals; most home and business wireless Communication Systems networks use Wi-Fi. Communication systems transmit data from one loca- • Microwave— line-of-sight communication; used tion to another. Four basic elements are to send data between buildings; longer distances • Sending and receiving devices require microwave stations. • Communication channel (transmission medium) • WiMax (Worldwide Interoperability for Microwave Access)— extends the range of Wi-Fi • Connection (communication) devices networks using microwave connections. • Data transmission specifications • LTE (Long Term Evolution) —currently has similar performance to WiMax; promises to provide greater speed and quality transmissions in the near future. • Satellite—uses microwave relay stations in the sky; GPS (global positioning system) tracks geographic locations. • Infrared —uses light waves over a short distance; line-of-sight communication.

232 CHAPTER 8

oole16864_ch08_210-239.inddle16864_ch08_210-239.indd 223232 110/29/120/29/12 12:4312:43 PMPM Rev.Confirming Pages

To be a competent end user you need to understand the concepts of connectivity, the wireless revolution, and communication systems. Additionally, you need to know the essential parts of communication technology, including channels, connection devices, data transmission, networks, network architectures, and network types.

CONNECTION DEVICES NETWORKS

Computer networks connect two or more computers. Some specialized network terms include • Node —any device connected to a network. • Client —node requesting resources. • Server —node providing resources. • Directory server —specialized node that manages resources. • Host —any computer system that can be accessed over a network. • Router —a node that forwards data packets from one network to another network. • Switch —node that coordinates direct flow of data Many communication systems use standard tele- between other nodes. Hub is an older device that phone lines and analog signals. Computers use digital directed flow to all nodes. signals. • NIC (network interface card) —LAN adapter card Modems for connecting to a network. • NOS (network operating system) —controls and Modems modulate and demodulate . Transfer rate is coordinates network operations. measured in megabits per second. Four types are telephone, DSL, cable, and wireless (wireless wide area • Network administrator —network specialist network, WWAN). responsible for network operations. Connection Service T1, T3 (DS3), and OC (optical carrier) lines provide NETWORK TYPES support for very high speed, all-digital transmission for large corporations. More affordable technologies Networks can be citywide or even international, using include dial-up, DSL (digital subscriber line), ADSL both wired and wireless connections. (widely used), cable, satellite , and cellular services. • Local area networks (LANs) connect nearby 4G (fourth-generation mobile telecommunications) devices. Network gateways connect networks to promises 10 times faster speeds than 3G . one another. Ethernet is a LAN standard. These LANs are called Ethernet LANs. • Home networks are LANs used in homes. DATA TRANSMISSION • Hotspots provide Internet access typically using Wi-Fi technology. Bandwidth measures a communication channel’s • Wireless LANs (WLANs) use a wireless access width or capacity. Four bandwidths are voiceband point (base station) as a hub. (low bandwidth), medium band, broadband (high- capacity transmissions), and baseband . Protocols are • Personal area networks (PANs) are wireless net- rules for exchanging data. Widely used Internet pro- works for PDAs, cell phones, and other small tocols include http, https, and TCP/IP . IP addresses gadgets. (Internet protocol addresses) are unique numeric • Metropolitan area networks (MANs) link office Internet addresses. DNS (domain name server) con- buildings within a city, spanning up to 100 miles. verts text-based addresses to and from numeric IP • Wide area networks or WANs are the largest type. addresses. Packets are small parts of messages. They span states and countries or form worldwide networks. The Internet is the largest wide area network in the world.

Communications and Networks 233

oole16864_ch08_210-239.inddle16864_ch08_210-239.indd 223333 110/29/120/29/12 12:4312:43 PMPM Rev.Confirming Pages

NETWORK ARCHITECTURE ORGANIZATIONAL NETWORKS

Internet Technologies Network architecture describes how networks are Internet technologies support effective communica- arranged and resources are shared. tion using intranets and extranets. Topologies • Intranet —private network within an organization; uses browsers, websites, and web pages. Typical A network’s topology describes the physical arrange- applications include electronic telephone directo- ment of a network. ries, e-mail addresses, employee benefit informa- • Bus network— each device is connected to a tion, internal job openings, and much more. common cable called a bus or backbone. • Extranet —like intranet except connects more than • Ring network— each device is connected to two one organization; typically allows suppliers and other devices, forming a ring. others limited access to their networks. • Star network—each device is connected directly to a central network switch; most common type Network Security today. Three technologies commonly used to ensure net- • Tree (hierarchical) network —a central node is work security are firewalls, intrusion detection sys- connected to subordinate nodes forming a treelike tems, and virtual private networks. structure. • Firewall —controls access; all communications • Mesh network —newest; each node has two or pass through proxy server. more connecting nodes. • Intrusion detection systems (IDS) —work with firewalls; use sophisticated statistical techniques Strategies to recognize and disable network attacks. Every network has a strategy, or way of sharing infor- • Virtual private network (VPN) —creates secure mation and resources. Common network strategies private connection between remote user and orga- include client/server and peer-to-peer. nization’s internal network. • Client/server (hierarchical) network —central computers coordinate and supply services to other nodes; based on specialization of nodes; widely CAREERS IN IT used on the Internet; able to handle very large networks efficiently; powerful network management Network administrators manage a company’s software available. LAN and WAN networks. Bachelor’s or specialized • Peer-to-peer network —nodes have equal authority advanced associate’s degree in computer science, and act as both clients and servers; widely used to computer technology, or information systems and share games, movies, and music over the Internet; practical networking experience required. Salary easy to set up and use; lacks security controls. range is $46,000 to $84,000.

234 CHAPTER 8

oole16864_ch08_210-239.inddle16864_ch08_210-239.indd 223434 110/29/120/29/12 12:4312:43 PMPM Rev.Confirming Pages

KEY TERMS

1G (first-generation downlink (215) optical carrier (OC) (217) mobile telecommuni- DS3 (217) packet (220) cations) (218) Ethernet (223) peer-to-peer (P2P) 2G (second-generation Ethernet cable (214) network (227) mobile telecommuni- extranet (227) personal area network cations) (218) fiber-optic cable (214) (PAN) (224) 3G (third-generation firewall (228) protocol (220) mobile telecommuni- global positioning system proxy server (228) cations) (218) (GPS) (215) ring network (225) 4G (fourth-generation hierarchical network (226) router (222) mobile telecommuni- home network (223) satellite (215) cations) (218) host (222) satellite connection analog signal (216) hotspot (224) service (217) asymmetric digital subscriber http (hypertext transfer server (221) line (ADSL) (217) protocol) (220) star network (225) backbone (225) https (hypertext transfer strategy (226) bandwidth (218) protocol secure) (220) switch (222) base station (223) hub (222) T1 (217) baseband (218) infrared (216) T3 (217) Bluetooth (215) intranet (227) telephone line (214) broadband (218) intrusion detection system telephone modem (216) bus (225) (IDS) (228) topology (225) bus network (225) IP address (Internet transfer rate (216) cable modem (217) protocol address) (220) transmission control cable service (217) local area network protocol/Internet protocol cellular service (LAN) (222) (TCP/IP) (220) provider (218) low bandwidth (218) tree network (226) client (221) LTE (Long Term twisted-pair cable (214) client/server Evolution) (215) uplink (215) network (226) medium band (218) virtual private network coaxial cable (214) megabits per second (VPN) (229) communication (Mbps) (216) voiceband (218) channel (214) mesh network (226) wide area network communication metropolitan area network (WAN) (224) system (213) (MAN) (224) Wi-Fi (wireless computer network (221) microwave (215) fidelity) (215) connectivity (212) modem (216) WiMax (Worldwide demodulation (216) modulation (216) Interoperability for dial-up service (217) network Microwave Access) (215) digital signal (216) administrator (222, 229) wireless access digital subscriber line network architecture (225) point (223) (DSL) (216) network gateway (223) wireless LAN digital subscriber line network interface card (WLAN) (223) (DSL) service (217) (NIC) (222) wireless modem (217) directory server (222) network operating system wireless wide area domain name server (NOS) (222) network (WWAN) (DNS) (220) node (221) modem (217) To test your knowledge of these key terms with animated flash cards, visit our website at www.computing2014.com and enter the keyword terms8 . Or use the free Computing Essentials 2014 app.

CHAPTER 8 235

oole16864_ch08_210-239.inddle16864_ch08_210-239.indd 223535 110/29/120/29/12 12:4312:43 PMPM Rev.Confirming Pages

MULTIPLE CHOICE

Circle the letter of the correct answer.

1 . The concept related to using computer networks to link people and resources. a . connectivity c. TCP/IP b. GPS d. Wi-Fi 2 . A high-frequency transmission cable that delivers television signals as well as connects computers in a network. a . coaxial c. 3-D b. hi def d. twisted pair 3 . A short-range radio communication standard that transmits data over short distances of up to approximately 33 feet. a . Bluetooth c. DSL b. broadband d. TCP/IP 4 . The speed with which a modem transmits data is called its: a . digital velocity c. modular rating b. dynamic rate d. transfer rate 5 . The bandwidth typically used for DSL, cable, and satellite connections to the Internet. a . baseband c. medium band b. broadband d. voiceband 6 . Every computer on the Internet has a unique numeric address called a(n): a . IP address c. broadcast b. DNS d. p a c k e t 7 . Sometimes referred to as a LAN adapter, these expansion cards connect a computer to a network. a . PCMCIA c. server b. NIC d. VPN 8 . A device that allows one LAN to be linked to other LANs or to larger networks. a . IDS c. PAN b. network gateway d. switch 9 . Typically using Wi-Fi technology, these wireless access points are available from public places such as coffee shops, libraries, bookstores, colleges, and universities. a . hotspots c. PANs b. extranets d. LANs 10. Bus, ring, star, tree, and mesh are five types of network: a . topologies c. strategies b. protocols d. devices

For an interactive multiple-choice practice test, visit our website at www. computing2014 .com and enter the keyword multiple8 . Or use the free Computing Essentials 2014 app.

236 CHAPTER 8

oole16864_ch08_210-239.inddle16864_ch08_210-239.indd 223636 110/29/120/29/12 12:4312:43 PMPM Rev.Confirming Pages

MATCHING

Match each numbered item with the most closely related lettered item. Write your answers in the spaces provided.

a . analog 1. Type of network topology in which each device is b. bus connected to a common cable called a backbone. c. intrusion 2. Uses radio signals to communicate between wireless detection systems devices. d. microwave 3. Uses high-frequency radio waves. e. network 4. Signals that are continuous electronic waves. administrator 5. Rules for exchanging data between computers. f. node 6. Any device that is connected to a network. g. peer-to-peer 7. A computer specialist responsible for efficient network h. protocols operations and implementation of new networks. i. RF 8. This network, also known as a hierarchical network, is j. tree often used to share corporatewide data. 9. In this network, nodes have equal authority and can act as both clients and servers. 10. Work with firewalls to protect an organization’s network.

For an interactive matching practice test, visit our website at www.computing2014.com and enter the keyword matching8 . Or use the free Computing Essentials 2014 app. OPEN-ENDED

On a separate sheet of paper, respond to each question or statement. 1 . Define communications including connectivity, the wireless revolution, and communication systems. 2 . Discuss communication channels including physical connections (twisted-pair, coaxial, and fiber-optic cable) and wireless connections (Bluetooth, Wi-Fi, microwave, WiMax, LTE, satellite, and infrared). 3 . Discuss connection devices including modems (telephone, DSL, cable, and wireless modems) and connection services (DSL, ADSL, cable, satellite, and cellular connection services). 4 . Discuss data transmission including bandwidths (voiceband, medium band, broadband, and baseband) as well as protocols (IP addresses, domain name servers, and packetization). 5 . Discuss networks by identifying and defining specialized terms that describe computer networks. 6 . Discuss network types including local area, home, wireless, personal, metropolitan, and wide area networks. 7 . Define network architecture including topologies (bus, ring, star, tree, and mesh) and strategies (client/server and peer-to-peer). 8 . Discuss organization networks including Internet technologies (intranets and extranets) and network security (firewalls, proxy servers, intrusion detection systems, and virtual private networks).

CHAPTER 8 237

oole16864_ch08_210-239.inddle16864_ch08_210-239.indd 223737 110/29/120/29/12 12:4312:43 PMPM