IS test one

Communication channel

A communications channel is such a pathway. It is comprised of two types of media: cable (twisted- pair wire, coaxial cable, or fiber-optic cable) and broadcast (microwave, satellite, radio, or infrared).

Portals

A portal is a Web-based, personalized gate- way to information and knowledge that provides relevant information from different IT systems and the Internet using advanced search and indexing techniques. After reading the next sec- tion, you will be able to distinguish among four types of portals: commercial, affinity, corpo- rate, and industrywide. The four types of portals are differentiated by the audiences they serve. A commercial (public) portal is the most popular type of portal on the Internet. It is intended for broad and diverse audiences, and it offers routine content, some of it in real time an affinity portal offers a single point of entry to an entire community of affili- ated interests, such as a hobby group or a political party. Your university most likely has an affinity portal for its alumni. a corporate portal offers a personalized, single point of access through a Web browser to critical business information located inside and outside an organization. These portals are also known as enterprise portals, information portals, and enterprise informa- tion portals. In addition to making it easier to find needed information, corporate portals offer customers and employees self-service opportunities.

Router

A router is a communications processor that routes messages from a LAN to the Internet, across several connected LANs, or across a wide area network such as the Internet.

Search engines

A search engine is a computer program that searches for specific information by keywords and then reports the results. A search engine maintains an index of billions of Web pages. It uses that index to find pages that match a set of user-specified keywords. Such indexes are created and updated by webcrawlers, which are computer programs that browse the Web and create a copy of all visited pages. Search engines then index these pages to provide fast searches. Metasearch engines search several engines at once and then integrate the findings to answer users' queries. Exam- ples are Surf-wax (www.surfwax.com), Metacrawler (www.metacrawler.com), Mamma (www. mamma.com), KartOO (www.kartoo.com), and Dogpile (www.dogpile.c

Connecting to the internet

An Internet service provider (ISP) is a company that provides Internet connections for a fee. Large ISPs include Comcast ( ISPs connect to one another through network access points (NAPs). NAPs are exchange points for Internet traffic. They determine how traffic is routed. NAPs are key components of the Internet backbone.

Intranet

An intranet is a network that uses Internet protocols so that users can take advantage of familiar applications and work habits. Intranets support discovery (easy and inexpensive browsing and search), communication, and collaboration inside an organization.

Bandwith

Bandwidth refers to the transmission capacity of a network; it is stated in bits per second. Bandwidth ranges from narrowband (relatively low transmission capacity) to broadband (relatively high network capacity).

Cable vs dsl modems

Cable: Cable modems are modems that operate over coaxial cable—for example, cable TV. They offer broadband access to the Internet or corporate intranets. Cable modem speeds vary widely. Most providers offer bandwidth between 1 and 6 million bits per second (Mbps) for downloads (from the Internet to a computer) and between 128 and 768 thousand bits per second (Kbps) for uploads. Cable modem services share bandwidth among subscribers in a locality. DSL: DSL modems operate on the same lines as voice telephones and dial-up modems. DSL modems always maintain a connection, so an Internet connection is immediately available.

Client Service Computing

Client/server computing links two or more computers in an arrangement in which some machines, called servers, provide computing services for user PCs, called clients. Usually, an organization performs the bulk of its processing or application/data storage on suitably powerful servers that can be accessed by less powerful client machines. The client requests applications, data, or processing from the server, which acts on these requests by "serving" the desired commodity. Client/server computing leads to the ideas of "fat" clients and "thin" clients. As discussed in Technology Guide 1, fat clients have large storage and processing power and therefore can run local programs (such as Microsoft Office) if the network goes down. In contrast, thin clients may have no local storage and only limited processing power. Thus, they must depend on the network to run applications. For this reason, they are of little value when the network is not functioning.

Coaxial cable

Coaxial cable (Figure 6.4) consists of insulated copper wire. Compared with twisted-pair wire, it is much less susceptible to electrical interference, and it can carry much more data. For these reasons, it is commonly used to carry high-speed data traffic as well as television signals (thus the term cable TV).

DSL

DSL and cable fall within the range of transmission capacity mentioned here and are thus defined as broadband connections. The various types of computer networks range from small to worldwide. They include (from smallest to largest) personal area networks (PANs), local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), and the ultimate WAN, the Internet. PANs are short-range networks—typically a few meters—that are used for communication among devices close to one person. They can be wired or wireless. (You will learn about wire- less PANs in Chapter 8.) MANs are relatively large computer networks that cover a metropoli- tan area. MANs fall between LANs and WANs in size. WANs typically cover large geographical areas; in some cases they can span the entire planet.

Fiber optic cable

Fiber-optic cable (Figure 6.5) consists of thousands of very thin filaments of glass fibers that transmit information via light pulses gener- ated by lasers. The fiber-optic cable is surrounded by cladding, a coating that prevents the light from leaking out of the fiber.

Hypertext

Hypertext is the underlying concept defining the structure of the World Wide Web. Hyper- text is the text displayed on a computer display or other electronic device with references, called hyperlinks, to other text that the reader can immediately access, or where text can be revealed progressively at additional levels of details. A hyperlink is a connection from a hyper- text file or document to another location or file, typically activated by clicking on a highlighted word or image on the screen, or by touching the screen.

Address on the internet

ISPs connect to one another through network access points (NAPs). NAPs are exchange points for Internet traffic. They determine how traffic is routed. NAPs are key components of the Internet backbone.

LAN

Local area network= connects two or more devices in a limited geographical region, usually within the same building, so that every device on the network can communicate with every other device. Most LANs today use Ethernet (discussed later in this chapter). Figure 6.1 illustrates an Ethernet LAN that consists of four computers, a server, and a printer, all of which connect via a shared cable. Every device in the LAN has a network interface card (NIC) that allows the device to physically connect to the LAN's communications medium. This medium is typically unshielded twisted-pair wire (UTP).

Peer to peer processing

Peer-to-peer (P2P) processing is a type of client/server distrib- uted processing where each computer acts as both a client and a server. Each computer can access (as assigned for security or integrity purposes) all files on all other computers. There are three basic types of peer-to-peer processing. The first type accesses unused CPU power among networked computers. An application of this type is SETI@home (http://setiathome.ssl.berkeley.edu). These applications are from open-source projects, and they can be downloaded at no cost. The second form of peer-to-peer is real-time, person-to-person collaboration, such as Micro- soft SharePoint Workspace (http://office.microsoft.com/en-us/sharepoint-workspace). This prod- uct provides P2P collaborative applications that use buddy lists to establish a connection and allow real-time collaboration within the application. The third peer-to-peer category is advanced search and file sharing. This category is char- acterized by natural language searches of millions of peer systems. It enables users to discover other users, not just data and Web pages. One example of this category is BitTorrent.

TCP/IP

The Transmission Control Pro- tocol/Internet Protocol (TCP/IP) is the protocol of the Internet. TCP/IP uses a suite of proto- cols, the main ones being the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The TCP performs three basic functions: (1) It manages the movement of data packets (see below) between computers by establishing a connection between the computers, (2) it sequences the transfer of packets, and (3) it acknowledges the packets that have been transmit- ted. The Internet Protocol (IP) is responsible for disassembling, delivering, and reassembling the data during transmission.

The world wide web

The World Wide Web (The Web, WWW, or W3) is a system of universally accepted stan- dards for storing, retrieving, formatting, and displaying information via a client/server architec- ture. The Web handles all types of digital information, including text, hypermedia, graphics, and sound. It uses graphical user interfaces (GUIs) (explained in Technology Guide 2), so it is very easy to navigate.

Internet backbone

The pri- mary network connections and telecommunications lines that link the nodes are referred to as the Internet backbone. For the Internet, the backbone is a fiber-optic network that is operated primarily by large telecommunications companies. As a network of networks, the Internet enables people to access data in other organizations and to communicate, collaborate, and exchange information seamlessly around the world, quickly and inexpensively. Thus, the Internet has become a necessity for modern businesses.

Twisted pair wire

Twisted-pair wire is the most prevalent form of communications wir- ing and is used for almost all business telephone wiring. As the name suggests, it consists of strands of copper wire twisted in pairs (see Figure 6.3). Twisted-pair wire is relatively inexpen- sive to purchase, widely available, and easy to work with.

WAN

Wide area network. A wide area network (WAN) is a network that covers a large geographical area. WANs typi- cally connect multiple LANs. They are generally provided by common carriers such as tele- phone companies and the international networks of global communications services providers. Examples of these providers include AT&T (www.att.com) in the United States, Deutsche Telekom in Germany (www.telekom.com), and NTT Communications (www.ntt.com) in Japan. WANs have large capacity, and they typically combine multiple channels (e.g., fiber-optic cables, microwave, and satellite). The Internet is an example of a WAN. contain routers.

Wireline media/cable media

Wireline media or cable media use physical wires or cables to transmit data and informa- tion. Twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass. The alternative is communication over broadcast media or wireless media. The key to mobile communications in today's rapidly moving society is data transmissions over electro- magnetic media—the "airwaves."

Extranet

an extranet connects parts of the intranets of different organizations. In addi- tion, it enables business partners to communicate securely over the Internet using virtual pri- vate networks (VPNs) (explained in Chapter 4). Extranets offer limited accessibility to the intranets of participating companies, as well as necessary interorganizational communications. They are widely used in the areas of business-to-business (B2B) electronic commerce (see Chapter 7) and supply chain management (SCM) (see Chapter 11).

Backbone networks.

backbone networks are high-speed central networks to which multiple smaller networks (such as LANs and smaller WANs) connect. The LANs are called embedded LANs because they con- nect to the backbone WAN.

Broadband

broadband as the transmission capacity of a communications medium (discussed later in this chapter) faster than 25 megabits per second (Mbps) for download (transmission speed for material coming to you from an Internet server, such as a movie streamed from Netflix) and 4 Mbps for upload (transmission speed for material that you upload to an Internet server such as a Facebook post). The definition of broadband remains fluid, however, and it will undoubt- edly continue to change to reflect greater transmission capacities in the future.

Digital signals

computer networks communicate via digital signals, which are discrete pulses that are either on or off, representing a series of bits (0's and 1's). This quality allows digital signals to convey information in a binary form that can be interpreted by computers.