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Computer Concepts 5th Edition Parsons/Oja Page 216 CHAPTER 5 Network Building Blocks Section A PARSONS/OJA Internet and LAN Technology
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Computer Concepts 5th Edition Parsons/Oja Page 218 Section A Chapter 5 Network Building Blocks Transmitting Data: Is it easy to transmit data? A communications network is a collection of computers and other devices that communicate to share data, hardware and software
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Computer Concepts 5th Edition Parsons/Oja Page 219 Section A Chapter 5 Network Building Blocks What kind of coding process happens on a communication network? Computers use several coding schemes based on binary digits ASCII EBCDIC Unicode Binary numbers
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Computer Concepts 5th Edition Parsons/Oja Page 220 Section A Chapter 5 Network Building Blocks Exactly what is transmitted when I send a message? When data is transmitted, it usually takes the form of an electromagnetic signal On a communication network, your data may be converted into several different types of waves
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Computer Concepts 5th Edition Parsons/Oja Page 220 Section A Chapter 5 Network Building Blocks Exactly what is transmitted when I send a message?
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Computer Concepts 5th Edition Parsons/Oja Page 221 Section A Chapter 5 Network Building Blocks Network Links: How do signals travel over a network? Data can travel from one network device to another over a cable or through the air A communications channel is a physical path or a frequency for a signal frequency Networks use different types of cables
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Computer Concepts 5th Edition Parsons/Oja Page 221 Section A Chapter 5 Network Building Blocks How do signals travel over a network? Today’s networks use twisted-pair cables UTP (unshielded twisted pair) STP (shielded twisted pair) looks similar to telephone cable has square plastic RJ-45 connector
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Computer Concepts 5th Edition Parsons/Oja Page 221 Section A Chapter 5 Network Building Blocks How do signals travel over a network? Another option is coaxial cable resembles cable-TV cable round, silver BNC connector
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Computer Concepts 5th Edition Parsons/Oja Page 221-222 Section A Chapter 5 Network Building Blocks How do signals travel over a network? Fiber-optic cable is a bundle of extremely thin tubes of glass Each optical fiber (tube) is thinner than a human hair Consists of strong inner support wire, multiple strands of optical fiber and a tough outer cable Transmit pulses of light Data can also travel airways in form of RF signals sent and received by a transceiver
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Computer Concepts 5th Edition Parsons/Oja Page 222 Section A Chapter 5 Network Building Blocks How do signals travel over a network? Microwaves provide another option for transporting data Radio and microwave transmissions are bent around the surface of the earth to reach towers Communications satellites play an important part in long-distance communications A transponder on the satellite receives the signal, amplifies it, and retransmits the signal back to a ground station
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Computer Concepts 5th Edition Parsons/Oja Page 222 Section A Chapter 5 Network Building Blocks How do signals travel over a network? Infrared light can also carry data signals, but for short distances with a clear line of sight Best for transmitting between notebook computers and a printer, or between a PDA and a desktop computer Laser light can also carry data signals, for a longer distance, but requires a clear line of sight Experimental, but possibly may be useful for transmitting data between buildings
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Computer Concepts 5th Edition Parsons/Oja Page 222 Section A Chapter 5 Network Building Blocks What’s bandwidth? Bandwidth is the transmission capacity of a communications channel High-bandwidth communications systems, such as cable TV, are sometimes referred to as broadband Systems with less capacity, such as the telephone system, are referred to as narrowband The bandwidth of a digital channel is usually measured in bits per second (bps)
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Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks Network Devices: What kind of equipment populates data communications networks? Each device that is connected to a network is referred to as a node The term workstation usually refers to a personal computer connected to a local area network (LAN), it is also called a client A modem is a device that converts signals from a computer into a signal that can travel over a wide area network
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Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks What kind of equipment populates data communications networks? A network interface card (NIC) is the key hardware component for connecting a computer to a local area network. small circuit board that sends data to and from workstation to network A server refers to any computer on a LAN or the Internet that contains the software to manage and process files for other network nodes
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Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks What kind of equipment populates data communications networks? A host computer usually refers to any computer that provides services to network users A hub is a device that connects several nodes of a LAN A router is a device that is connected to at least two networks and makes decisions about the best route for data A gateway is a device that performs functions similar to a router A repeater amplifies and regenerates signals so they can retain the strength to reach their destinations
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Computer Concepts 5th Edition Parsons/Oja Page 223 Section A Chapter 5 Network Building Blocks Network Addresses: How does data find its destination? Every node on a network has an address Every packet of data that travels over a network also has an address which helps to route a packet to its destination
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Computer Concepts 5th Edition Parsons/Oja Page 224 Section A Chapter 5 Network Building Blocks Network Topology: Does a network require a certain configuration of nodes? The layout of a network is referred to as its physical topology
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Computer Concepts 5th Edition Parsons/Oja Page 224 Section A Chapter 5 Network Building Blocks Does a network require a certain configuration of nodes? A real-world network can make use of more than one topology
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Computer Concepts 5th Edition Parsons/Oja Page 225 Section A Chapter 5 Network Building Blocks Packet and Circuit Switching Technology: What’s a packet? When you transmit data, it is broken up into small pieces called packets A packet is a parcel of data that is sent across a network Has the address of its sender Has the address of the destination Has some data When they reach the destination, they are put back together into original form
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Computer Concepts 5th Edition Parsons/Oja Page 226 Section A Chapter 5 Network Building Blocks Why not just send an entire message? Engineers wanted a more robust communications link for computer networks They devised packet switching in which a message was divided into several packets that can be routed independently to their destination to avoid out-of-service or congested links Packet switching makes very efficient use of available bandwidth and provides a steady stream of data
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Computer Concepts 5th Edition Parsons/Oja Page 226 Section A Chapter 5 Network Building Blocks Communications Protocols: What is a communications protocol? Communications protocol refers to set of rules for transmitting data from one node to another Protocols allow two devices to negotiate and agree on how data will be transmitted Scripts for dial-up modem
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Computer Concepts 5th Edition Parsons/Oja Page 226-227 Section A Chapter 5 Network Building Blocks How does a protocol initiate a transmission? Protocols establish communications through handshaking The devices decide on how to coordinate its transmission Synchronous protocols are synchronized by a signal called a clock when sending and receiving data Asynchronous protocols require the transmitting computer to send a start bit, then data is sent, and a stop bit to mark the end of the data
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Computer Concepts 5th Edition Parsons/Oja Page 227 Section A Chapter 5 Network Building Blocks Does data travel in both directions over the same channel? Simplex – signal travels in only one direction Half duplex – signal travels in both directions, but only one direction at a time Full duplex – signal travels in both directions at the same time
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Computer Concepts 5th Edition Parsons/Oja Page 227 Section A Chapter 5 Network Building Blocks How does a protocol make sure that data arrives without errors? Computers use error-checking protocols to make ensure accurate delivery of data (such as over the Internet) Parity bit – added to keep track of the number of 1s and 0s Even parity protocol – requires number of 1s to be an even number
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Computer Concepts 5th Edition Parsons/Oja Page 228 Section A Chapter 5 Network Building Blocks Network Classifications: How are networks classified? Internetwork – a network composed of many smaller networks Intranet – uses TCP/IP protocols but owned by a private business and does not typically allow remote access Extranet – similar to intranet except that it allows remote password-protected access WAN – (wide area network) covers a large geographical area and may consist of smaller networks
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Computer Concepts 5th Edition Parsons/Oja Page 228 Section A Chapter 5 Network Building Blocks How are networks classified? LAN (local area network) – typically covers a very limited geographical area Wireless network – uses radio frequencies HomeRF network – low-power wireless network for home use HomePLC – uses building’s existing power line cables HomePNA – uses existing telephone cables Novell – LAN that uses Novell Netware
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Computer Concepts 5th Edition Parsons/Oja Page 229 Section A Chapter 5 Network Building Blocks How are networks classified? Ethernet – free for all
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Computer Concepts 5th Edition Parsons/Oja Page 229 Section A Chapter 5 Network Building Blocks How are networks classified? Token Ring – connects nodes in a physical star configuration, but passes data around a logical ring using a technology called a “token”. Wait for your turn…
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Computer Concepts 5th Edition Parsons/Oja Page 230 Section A Chapter 5 Network Building Blocks How are networks classified? Client/server – contains servers and clients Peer-to-peer (P2P) – every computer is considered an equal KaZaa: file sharing among peers
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Computer Concepts 5th Edition Parsons/Oja Page 231 Section B Chapter 5 Internet Building Blocks Background: How did the Internet get started? The United States created ARPA (Advanced Research Projects Agency). to help scientists communicate and share valuable computer resources in response to the Soviet Union’s launch of Sputnik in 1957, the first artificial satellite The ARPANET, created in 1969, connected computers at four universities
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Computer Concepts 5th Edition Parsons/Oja Page 231 Section B Chapter 5 Internet Building Blocks How did the Internet get started? In early 1990s, software developers created new user-friendly Internet access tools Web browser: created at the University of Illinois Today, the Internet connects computers all over the globe and supplies information to people of all ages and interests
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Computer Concepts 5th Edition Parsons/Oja Page 232 Section B Chapter 5 Internet Building Blocks Internet Hardware and Connections: What type of hardware populates Internet nodes? Difficult to diagram due to over 100 million nodes and 350 million users
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Computer Concepts 5th Edition Parsons/Oja Page 232 Section B Chapter 5 Internet Building Blocks What kinds of network devices are part of an ISP? An ISP operates network devices that handle the physical aspects of transmitting and receiving data from your computer Modems Domain name server Router
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Computer Concepts 5th Edition Parsons/Oja Page 233 Section B Chapter 5 Internet Building Blocks What kinds of network devices are part of an ISP? An ISP links to other ISPs in a sort of ISP network Network service Providers (NSPs) supply ISPs with access to high-speed transmission lines that form the backbone of the Internet Interstate highways of the Internet NSPs also provide routers at network connection points
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Computer Concepts 5th Edition Parsons/Oja Page 233 Section B Chapter 5 Internet Building Blocks How fast does data travel over the Internet? Using Ping or Traceroute, you can discover how long data is in transit On average, data within the US usually arrives at its destination 110-120 ms (milliseconds) after it is sent Overseas transmission require a little more time
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Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks Internet Protocols: Why does the Internet use TCP/IP? TCP/IP provides a standard that is fairly easy to implement, public, free, and extensible The Internet is not owned, operated, or controlled by any single entity TCP/IP is glue that holds the Internet together
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Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks How does TCP/IP work? It is a suite of protocols TCP (Transmission Control Protocol) – breaks a message or file into packets IP (Internet Protocol) – responsible for addressing packets so that they can be routed to their destination
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Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks Is TCP/IP the only Internet Protocol?
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Computer Concepts 5th Edition Parsons/Oja Page 234 Section B Chapter 5 Internet Building Blocks IP Addresses: Does the Internet use a special addressing scheme? The IP part of TCP/IP defines the format for the addresses that identify computers on the Internet These addresses are called IP addresses An IP address is a series of numbers, such as 204.127.129.001 It is separated into four sections by periods Each section’s number cannot exceed 255 Each address requires 32 bits (8 bits per section)
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Computer Concepts 5th Edition Parsons/Oja Page 235 Section B Chapter 5 Internet Building Blocks Do I need a permanent IP address? Static IP address – permanently assigned IP address Dynamic IP address – temporarily assigned ISPs need static IP addresses Clients typically use dynamic IP addresses as the IP addressing scheme provides approximately only 4.3 billion unique addresses
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Computer Concepts 5th Edition Parsons/Oja Page 235 Section B Chapter 5 Internet Building Blocks Domain Names: What’s a domain name? People find it difficult to remember long strings of numbers, so host computers also have names called domain names Domain name – “fully qualified domain name” (FQDN), usually typed in all lowercase Key component of URLs and e-mail addresses www.thex-files.com/episode236 - www.thex- files is the domain name
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Computer Concepts 5th Edition Parsons/Oja Page 236 Section B Chapter 5 Internet Building Blocks What’s a domain name? A domain name ends with an extension that indicates its top-level domain
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Computer Concepts 5th Edition Parsons/Oja Page 236 Section B Chapter 5 Internet Building Blocks How are domain names related to IP addresses? Each name corresponds to an IP address Domain name system – huge database that houses the names and IP addresses Domain name servers – computers that house the database
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Computer Concepts 5th Edition Parsons/Oja Page 237 Section B Chapter 5 Internet Building Blocks Do I need my own domain name? Not for normal client-style Internet activities If you plan to operate your own Web server, you may want a name
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Computer Concepts 5th Edition Parsons/Oja Page 237 Section B Chapter 5 Internet Building Blocks How do I get a domain name? ICANN (Internet Corporation for Assigned Names and Numbers) – global organization that coordinates the technical management of the Internet’s domain name system, allocation of IP addresses, and the assignment of protocol parameters Organizations or individuals can select a domain name and register it by using an online registration service
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Computer Concepts 5th Edition Parsons/Oja Page 237 Section B Chapter 5 Internet Building Blocks How do I get a domain name? Click to start
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Computer Concepts 5th Edition Parsons/Oja Page 238 Section B Chapter 5 Internet Building Blocks Is a fee required to obtain a domain name? You can register a domain name for a minimal annual fee ($25 - $50) Some Internet entrepreneurs have registered high-profile domain names and resell them Sell-videos.com - $35,000 Thelocallistings.com - $87,500
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Computer Concepts 5th Edition Parsons/Oja Page 240 Section C Chapter 5 Internet Access Dial-Up Connections: How does a dial- up connection work? Uses POTS (plain old telephone service) to transport data between your computer and your ISP
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Computer Concepts 5th Edition Parsons/Oja Page 241 Section C Chapter 5 Internet Access How does a dial-up connection work? While connected to your ISP, your call is routed through the telephone company’s local switch to the ISP Local Switch
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Computer Concepts 5th Edition Parsons/Oja Page 241 Section C Chapter 5 Internet Access How does a modem work?
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Computer Concepts 5th Edition Parsons/Oja Page 242 Section C Chapter 5 Internet Access Can I talk and send data at the same time? When connected to ISP, data is transmitted in same frequencies used for voice conversations
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Computer Concepts 5th Edition Parsons/Oja Page 242 Section C Chapter 5 Internet Access How fast is a modem? Speed was measured as baud rate, number of times per second that a signal in a communications channel varies speeds Today, measure in terms of bits per second V.90 – theoretical maximum speed of 56 Kbps Even with perfect connection, a 56 Kbps modem tops out at about 44 Kbps Downstream vs. upstream
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Computer Concepts 5th Edition Parsons/Oja Page 243 Section C Chapter 5 Internet Access Cable Television Connections: How can the cable TV system provide Internet access? Community antenna television – CATV The satellite dish farm at which television broadcasts are received and retransmitted is referred to as the head-end From the head-end, cabling system branches out and eventually reaches consumers’ homes Topology is similar to computer network, and that is what is formed when you use cable TV as your ISP
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Computer Concepts 5th Edition Parsons/Oja Page 243 Section C Chapter 5 Internet Access How can the cable TV system provide Internet access?
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Computer Concepts 5th Edition Parsons/Oja Page 244 Section C Chapter 5 Internet Access Are television and data signals carried over the same cable? Lowest-capacity coaxial cable has far greater capacity than POTS lines Cable’s bandwidth is divided among 3 activities
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Computer Concepts 5th Edition Parsons/Oja Page 244 Section C Chapter 5 Internet Access How do I set up a cable modem connection? Need an Ethernet NIC Need a cable modem, which converts your computer’s signal into one that can travel over CATV cable
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Computer Concepts 5th Edition Parsons/Oja Page 245 Section C Chapter 5 Internet Access What’s the significance of becoming part of a “neighborhood network”? With CATV, your computer becomes part of a neighborhood data network More people on the network, means slower service Also, in early days your network neighborhood showed your neighbors
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Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access What’s the significance of becoming part of a “neighborhood network”? An always-on connection is always connected A hacker who discovers that your computer has a security weakness can easily find it again, and its high-speed access makes it a very desirable target
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Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access How do I secure an always-on connection? Disable file and print sharing
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Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access How do I secure an always-on connection? Shut down your computer when you are not using it Install personal firewall software, which is designed to analyze and control incoming and outgoing packets Pick level – high, medium, or low
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Computer Concepts 5th Edition Parsons/Oja Page 246 Section C Chapter 5 Internet Access DSL, ISDN, T1, and T3: What other options are available for high-speed Internet access? Several services such as DSL, ISDN, T1, and T3 take advantage of full capacity of the telephone connections (normal dial-up services do not) Offers high-speed digital communications links for voice and data
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Computer Concepts 5th Edition Parsons/Oja Page 247 Section C Chapter 5 Internet Access What is DSL? DSL (Digital Subscriber Line) is a high-speed, always-on, Internet access technology that runs over standard phone lines
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Computer Concepts 5th Edition Parsons/Oja Page 247 Section C Chapter 5 Internet Access What is DSL?
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Computer Concepts 5th Edition Parsons/Oja Page 248 Section C Chapter 5 Internet Access What is DSL? Speed varies, but most are rated at 1.5 Mbps downstream
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Computer Concepts 5th Edition Parsons/Oja Page 248 Section C Chapter 5 Internet Access How do I install DSL? Telephone line connected to DSL switch at your house Line connected to DSL modem which connects to your computer’s Ethernet card
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Computer Concepts 5th Edition Parsons/Oja Page 249 Section C Chapter 5 Internet Access Who uses T1 or T3 service? T1 – high-speed 1.544 Mbps digital network Consists of 24 individual channels (64 Kbps for each) Popular for businesses and ISPs Not as fast as DSL T3 672 channels Supports data rates of about 43 Mbps Sometimes referred to as DS3 (Digital Service-3) lines Provide many of the links on the Internet backbone
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Computer Concepts 5th Edition Parsons/Oja Page 249 Section C Chapter 5 Internet Access Wireless Internet Access: What are the options for wireless connections to the Internet? Personal satellite connections – expensive, but sometimes only option (particularly in remote rural areas) Cellular telephones – slowest, but provides mobile Internet access
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Computer Concepts 5th Edition Parsons/Oja Page 249-250 Section C Chapter 5 Internet Access How does satellite access work? Direct satellite service (DSS) uses a geosynchronous or low-earth satellite to send television, voice, or computer data directly to a satellite dish Two-way satellite service ships both upstream and downstream data through the satellite offers 500 Kbps downstream 40-60 Kbps upstream
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Computer Concepts 5th Edition Parsons/Oja Page 249 Section C Chapter 5 Internet Access How does satellite access work?
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Computer Concepts 5th Edition Parsons/Oja Page 251 Section C Chapter 5 Internet Access What’s the fastest Internet connection?
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Computer Concepts 5th Edition Parsons/Oja Page 254 Section D Chapter 5 LAN Technology LAN Services and Resources: What sort of resources does a LAN provide? Main advantage of a LAN is that multiple users can share a limited number of resources Can share a high-speed connection
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Computer Concepts 5th Edition Parsons/Oja Page 254 Section C Chapter 5 LAN Technology How do I access network resources? When you boot your computer, OS looks to see if it can access a LAN Generally need to reboot after loosing network connection The OS keeps track of network resources you can access automatically Some network resources become available as soon as your computer completes the boot process, and others after you use your networking utilities
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Computer Concepts 5th Edition Parsons/Oja Page 255-256 Section D Chapter 5 LAN Technology Can a LAN use existing phone or electrical wiring? HomePNA uses a special NIC and cable to connect each computer to a standard telephone wall jack Network frequency is usually different from voice, so can use network at same time you place a call You can not make a call when dial-up Internet connection is active however HomePLC uses special NIC to connect to standard electrical outlet, but power fluctuations can adversely affect signal
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Computer Concepts 5th Edition Parsons/Oja Page 256 Section D Chapter 5 LAN Technology Can LANs use wireless technology? Wireless LANs are slower but eliminate unsightly wires Signals can be disrupted by large metal objects, cell phones, pagers, and other wireless devices Most popular s 802.11b 11 Mbps, spans 300 feet, and can be used with Ethernet networks Bluetooth 200-400 Kbps, range of 35 feet
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Computer Concepts 5th Edition Parsons/Oja Page 221-222 Section A Chapter 5 Network Building Blocks LANs with wireless technology Wi-Fi: Wireless Fidelity: Avoid expense of wiring installation for network Enjoy mobility Up to 100 times faster than dial-up connection 11 mps Range of 100 up to 1,000 feet Signals operate in the 2.4 and 5Ghz radio bands, which are also used today by many cordless phones Hot spot operators Starbucks, hotels, airports, etc.
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