Computer Network.pdf

COMPUTER NETWORKS AND WEB TECHNOLOGIES Done By: Sakae Simpson 10/17/2023 Lesson OBJECTIVES distinguish among types of networks; explain the functions of the basic components of a network; assess the importance of mobile communication technologies; explain the interrel...

COMPUTER NETWORKS AND WEB TECHNOLOGIES Done By: Sakae Simpson 10/17/2023 Lesson OBJECTIVES distinguish among types of networks; explain the functions of the basic components of a network; assess the importance of mobile communication technologies; explain the interrelationship among key web technology concepts. SAMPLE FOOTER TEXT 2 10/17/2023 Concept Map 3 10/17/2023 INTRODUCTION TO COMPUTER NETWORK SAMPLE FOOTER TEXT 4 10/17/2023 Computer Network A computer network is a group of computing devices that are joined together so that they can share data and resources. SAMPLE FOOTER TEXT 5 10/17/2023 Mobile Network A mobile network, often referred to as a cellular network or wireless network, is a telecommunications network that allows mobile devices (such as smartphones, tablets, and laptops) to connect to the internet and communicate with each other over a wireless connection. SAMPLE FOOTER TEXT 6 10/17/2023 Wi-Fi Wi-Fi (Wireless Fidelity) is a standard for wireless communication between computing devices. In a wired network computing devices communicate using physical wires. In a wireless network computing devices communicate using electromagnetic (radio) waves of different frequencies. Types of wireless communication are Bluetooth, Wi-Fi and mobile 2G (second generation), 3G, 4G (LTE) and 5G. Most networks are a combination of wired and wireless. 7 10/17/2023 Distinguish Among Types of Networks A computer network may be classified based on its geographic span. Computer networks are designed to meet the data communication needs of individuals and organisations. A small network may connect computers in multiple rooms in a building; large networks may connect computers in different countries. The three types of network based on geographic span are discussed below. SAMPLE FOOTER TEXT 8 10/17/2023 SAMPLE FOOTER TEXT 9 10/17/2023 Local area networks A local area network (LAN) is a computer network that interconnects computers within a limited area such as a home, school, laboratory or office building. Chances are there is a government office or a private organisation nearby that has a LAN in operation. The computer lab at your school may well have a local area network in operation. As a matter of fact, there may be more than one LAN in operation at your school. 10/17/2023 SAMPLE FOOTER TEXT 11 10/17/2023 Metropolitan area networks A metropolitan area network (MAN) is a computer network in a geographic area or region larger than that covered by a LAN. A local supermarket chain will have branches throughout the city. Each branch will have one or more local area networks, but they will all be networked to the head office in the city centre, creating a metropolitan area network. 12 10/17/2023 10/17/2023 Wide area networks A wide area network (WAN) is a computer network in which the computers connected may be far apart, even in different countries. WANs provide national, regional and international organisations with the connectivity needed to sustain their operations. SAMPLE FOOTER TEXT 14 10/17/2023 Common carrier A common carrier is a company that offers communication services to the general public. SAMPLE FOOTER TEXT 15  Internet Service Provider An internet service provider (ISP) is a company that has a direct connection to the internet and gives users access to it, usually for a fee. The company usually has a small network that is linked via a high-speed communications link to a high-speed link that forms part of the internet’s backbone (supercomputers and other large networks that make up the internet world wide). 10/17/2023 QUESTIONS What does the abbreviation "Wi-Fi" stand for? What type of network do you use on your cell phone? What type of network does a local dentist practice use? What type of network Jet Blue Airline use? What type of network PriceSmart Supermarket use? State one similarity and one difference between a computer network and a mobile network. 10/17/2023 Mobile networks as radio-based common carriers A mobile network is a network of communication and computing devices where the last link is over a mobile phone network. Mobile network services are operated by a few large companies in each country, for example Digicel and FLOW. Many computer networks rely on mobile networks to provided additional flexible connectivity. SAMPLE FOOTER TEXT 18 10/17/2023 Mobile networks Mobile networks started life as networks for cellular phones. They are called cell phones because of the way in which mobile networks work. A mobile phone mast has a radio transmitter and receiver at the top. The signals from the mast reach out in a circle – or cell. Any mobile phone within that cell can communicate with the mast. SAMPLE FOOTER TEXT 19 10/17/2023 Telephone Mast  10/17/2023 Mobile wireless standards Mobile wireless standards: from 2G to 5G First there was mobile technology, then second-generation mobile technology (2G). As of 2019, 3G and 4G are in widespread use around the Caribbean and the world. The change from 2G to 3G was a major breakthrough in communications. 3G receives a signal from the nearest mobile phone tower and is used for phone calls, messaging and data. It is generally accepted that 4G works the same as 3G but with a faster Internet connection. 4G claims to be around five times faster than existing 3G services.  Technology generation 10/17/2023 Expected download speed 1G up to 2.4 kbps (kilobits per second) 2G up to 64 kbps 3G up to 5 mbps (megabits per second) 4G up to 25 mbps 5G between 10 and 20 Gbps  Wireless network 10/17/2023 technologies Mobile networks aren’t the only wireless radio-based communication technologies used in Information Technology. Both Bluetooth and Wi-Fi are widely used. SAMPLE FOOTER TEXT 24 10/17/2023 Bluetooth Bluetooth is a wireless protocol for exchanging data over short distances from one device to another. SAMPLE FOOTER TEXT 25 10/17/2023 Protocol A protocol is a set of rules or an agreed way to exchange or transmit data between devices. SAMPLE FOOTER TEXT 26 10/17/2023 Hotspot A hotspot is a physical location where persons may obtain Internet access, typically using Wi-Fi technology. Public hotspots may be created by a business for use by customers in places such as coffee shops, restaurants, shopping malls and hotels. SAMPLE FOOTER TEXT 27 10/17/2023 Levels of privacy provided by an intranet, an extranet and the Internet SAMPLE FOOTER TEXT 28 Internet, Intranet and Extranet comparison 10/17/2023 Intranet An intranet is a private computer network where only authorised persons within an organisation can access resources. Intranets are designed to meet the needs of a single organisation that needs to keep its data private and secure. It usually utilises familiar facilities such as webpages and web browsers. 10/17/2023 Extranet An extranet is a private computer network where authorised persons within an organisation and selected partners outside the organisation can access specific resources. External partners access the organisation’s resources using the Internet, so an extranet is more at risk and less secure than an intranet. SAMPLE FOOTER TEXT 31 10/17/2023 Internet The Internet is a public, globally accessible, wide area network providing information and communication facilities. With its global reach, the Internet serves the data communication needs of businesses worldwide and billions of individuals. The Internet (inter network) is known as the ‘network of networks’ because it is the world’s largest network. A network is a collection of computers and devices joined together by communication devices and media. 10/17/2023 Encryption Encryption is the process of converting data/information to a code to prevent unauthorised persons from accessing it. 34  10/17/2023 Characteristic Internet Intranet Extranet Level of privacy Public: Anyone can Private: Only Private: Only authorised access authorised employees persons can access can access Ownership Not owned by Owned by a particular May be owned by one anyone organisation or more collaborating organisations Information Information can be Information can be Information can be sharing shared with shared securely within shared between everyone an organisation employees and external across the world colleagues SAMPLE FOOTER TEXT 35 10/17/2023 The Functions of the basic components of a network Networks are all around. As an Information Technology professional, you will need to understand the various elements of a network and how they work together. Earlier we established that two connection methods are available: wired and wireless. SAMPLE FOOTER TEXT 36 10/17/2023 Wired Network A wired network uses a wired medium such as twisted pair cable, optical fiber cable or coaxial cable to transfer data between connected devices. SAMPLE FOOTER TEXT 37 10/17/2023 Wireless Network A wireless network uses radio waves instead of physical cables as the transmission medium. SAMPLE FOOTER TEXT 38 10/17/2023 Most networks use a combination of wired and wireless technologies. A wired transmission medium carries data directly from one point to another whereas a wireless medium broadcasts the data, which is carried to all devices within its range. A range of hardware devices and transmission media is used in the creation and operation of a computer network. These are listed in the table below. Method of 10/17/2023 Networking devices Transmission connectivity media Wired Hub Cables Switch Coaxial Router Twisted pair network interface card/adapter Fibre optic Wireless wireless access point Bluetooth wireless adapter microwave radio satellite Wi-Fi SAMPLE FOOTER TEXT 40 10/17/2023 Network designers make decisions as to which type of transmission media to use based on a number of factors. These include: the physical environment, for example location of the rooms in relation to each other, their size, and the material used to construct the walls the volume of data that will be transmitted and received by the various devices the flexibility and convenience required by users’ devices, for example fixed desktop computers or mobile devices. 41 10/17/2023 Networks are created by combining computing devices (desktop computers, laptops, tablets and smartphones) and peripherals (printers, scanners, network-attached storage) to a central connection point known as a hub. We need to understand all the components used in a network: Transmission media are the cables that connect everything together. Hubs, routers and switches make sure that data gets directed to the right computer. Network interface cards and network adapters ensure that computers can receive the data. 42 10/17/2023 Transmission Media The transmission media are the mechanisms by which computing devices are connected together. Transmission media can be physical hardware (cables) or wireless media (infrared, Wi-Fi, Bluetooth, microwaves, satellites and mobile networks). SAMPLE FOOTER TEXT 43 10/17/2023 Physical wired network transmission media 10/17/2023 Twisted pair Twisted pair cable consists of eight copper wires, twisted in pairs to reduce interference and enclosed in a plastic covering. SAMPLE FOOTER TEXT 45 10/17/2023 Coaxial Cable Coaxial cable consists of a single copper core surrounded by a metal shield to reduce interference and all enclosed in a plastic covering. Coaxial cable was used during the 1980s to early 1990s but is hardly ever used in modern networks. SAMPLE FOOTER TEXT 46 10/17/2023 Fiber Optic Fiber optic cable consists of flexible fibers with a glass core; they carry information using light. SAMPLE FOOTER TEXT 47 10/17/2023 Wireless network transmission media SAMPLE FOOTER TEXT 48 10/17/2023 Infrared Infrared is part of the electromagnetic radiation spectrum at wavelengths that fall between visible light and radio waves at frequencies 300GHz up to 430THz. In terms of Information Technology, infrared communication works in the same way as Wi-Fi but at a different frequency. An example of infrared transmission is communication between a desktop and netbook computer where the distance is small and there is a clear line of sight between the two devices. The requirement for a clear line of sight between devices has limited the popularity of infrared communication. 10/17/2023 Microwaves Microwaves are part of the electromagnetic radiation spectrum at frequencies 300MHz to 300GHz. Like infrared, microwave communication works in the same way as Wi-Fi. The range of microwave transmission is many kilometres but there must be clear line of sight between the two antennae. Microwave communications can be used to connect remote locations to a network providing there is a clear line of sight: for example, a hilltop weather station may be networked to the valley-bottom laboratory using microwaves. SAMPLE FOOTER TEXT 50 10/17/2023 Satellite A satellite is a communication device orbiting in space that relays and amplifies radio telecommunication signals to and from remote locations. Connection devices 10/17/2023 Hub A hub is a multiport device that connects many computing devices together. A simple hub works by repeating data received from one of its ports to all other ports. Every computer linked to the hub ‘hears’ everything any of the other computers ‘says’ but ignores anything not meant for them. This is like a roundtable meeting. Participants sit round a table listening to others and asking questions but responding only when remarks or questions are addressed to them. 10/17/2023 SAMPLE FOOTER TEXT 54 10/17/2023 Router A router is an intelligent network device that connects two networks together. The term ‘Internet router’ refers to the device that home users and small offices use to connect their LAN to the Internet. It is usually a combined hub and router in one device. Acting as a hub it allows all your computing devices to be attached to each other, wired or wirelessly. The router is also connected to the Internet, usually via a telephone line, and it joins your local network to the Internet. 10/17/2023 Switch A switch is an intelligent device that routes incoming data directly to the specific output port that will take the data towards its intended destination. Switches and routers are similar devices but operate on a different technical level. For example, switches use MAC (Media Access Control) addresses while routers use IP (Internet Protocol) addresses. SAMPLE FOOTER TEXT 56 10/17/2023 Modem Modem is an abbreviation for modulator-demodulator, a device that converts signals from analogue to digital and vice versa. A modem allows computers to exchange information through telephone lines. Modems are now much less common because they offer only slow Internet connection and connect only a single computer to the Internet. Modems are being replaced by more up-to-date technologies. Network interface cards and network adapters  NETWORK INTERFACE CARD A network interface card (NIC) is a computer hardware component installed in a device into which a network cable may be plugged. As the name suggests, a wireless network interface card communicates wirelessly and has an antenna instead of a port that accepts a cable.  NETWORK ADAPTOR A network adapter is a converter that adapts/extends a USB port for it to function like a NIC or a wireless NIC. A network adapter is needed if the computing device does not have a built-in networking component. 10/17/2023 Importance of Mobile Communication Technologies 10/17/2023 Mobile networks in education In education, public school students are increasingly able to access services via mobile networks. Mobile networks are well suited to the education sector, providing access to streaming content from services like TeacherTube, YouTube and Khan Academy, and providing syllabi as enhanced eBooks from the Caribbean Examinations Council. 10/17/2023 Mobile networks used with mobile devices such as smartphones, laptops and tablets are playing an increasing role in education. They enable learning away from the traditional classroom environment where teacher and students are in the same room. Using mobile networks teachers and students don’t need to be in the same room; they don’t even need to be in the same country. 10/17/2023 When learning moves away from the classroom and onto a network, eBooks replace physical books, e-assessment replaces paper-based testing, videoconferencing replaces face-to-face tutor communication, and collaborative working online with shared documents replaces collaborative group working in the classroom. Activity monitoring is automatically performed by the system. CXC’s new interactive learning site ‘CXC Learning Hub’ is an example of how education is responding to the opportunities digital technology brings with it. 10/17/2023 Mobile networks in journalism Journalism is one of the first professions to reap the benefits of the new mobile network technology as it has developed with mobile devices such as smartphones, laptops and tablets. Journalists may be reporting on breaking or in-depth stories for newspapers, magazines, websites, TV or radio, or creating blogs and podcasts. Working to tight deadlines, a journalist would traditionally investigate the story and then return to the office to create the report.  10/17/2023 The use of mobile networks and smartphones allows a journalist to file a report on the go when a big story breaks. Camera applications allow the capture of video and still photographs, word processing apps allow words to be added to the story, and audio-recording apps allow for the capture of interviews for radio stations and podcasts. This content is then transmitted back to the editor in the office using mobile network communication. 10/17/2023 Mobile networks in commerce E-commerce or electronic commerce has been about for many years and involves trading products and services via the Internet and other computer networks. Examples include banking, retail, insurance and advertising. M-commerce has developed from e-commerce and involves using computing devices connected to the Internet via mobile networks to carry out e-commerce. The advantage of m-commerce is improved portability and flexibility. Typical commercial applications that use mobile networks include: 10/17/2023 Mobile banking. Checking your bank balance, paying directly using a smartphone, managing your accounts and executing money transfers are examples of mobile banking. Mobile buying and selling. Shopping can now be done on the move using your mobile. You can make purchases on the seller’s website or in their dedicated app. Mobile tickets, boarding passes and vouchers. Printed tickets are replaced with an electronic version containing a machine-readable barcode or QR code, which is scanned at the venue directly from a smartphone. 10/17/2023 Web technology concepts. SAMPLE FOOTER TEXT 69  The World Wide Web The World Wide Web is a huge collection of interlinked specially formatted documents, standards and protocols that reside on the Internet. Each specially formatted document is known as a web page, which is created using Hyper Text Markup Language (HTML), graphics, audio and video files. Web pages that are connected by hyperlinks and reside on a special computer known as a server are known as a web site. One example of a web site is Yahoo! Every Yahoo web page has the logo on it and maybe accessed via a hyperlink. 10/17/2023 Web Browser A web browser is a program that allows users to view and explore information on the World Wide Web. Web browsers such as Internet Explorer, Edge, Mozilla Firefox, Google Chrome and Apple’s Safari are available. You need a web browser application program to view web pages on the WWW. HyperText Markup Language (HTML). HTML is a programming language that you can use to create web pages. It contains standard codes that are used to specify how a web page is structured and formatted. They determine the appearance of the web page when it is displayed by your browser. HTML, also contains tags that are used to create hyperlinks to access related information on the web.  Hyperlink A hyperlink is a word, phrase, or image that you can click on to jump to a new document or a new section within the current document. A hyperlink is a piece of text or part of a web page or an image that when selected and clicked with the mouse displays another web page document (or resource). Hyperlinks are what make the WWW so easy to use. HyperText Transfer Protocol (HTTP) HyperText Transfer Protocol (HTTP) - the underlying protocol used by the World Wide Web that defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. It is the most commonly used protocol of those mentioned here. Hypertext Transfer Protocol is a protocol used to request and transmit files, especially web pages and web page components, over the Internet or other computer network.  File Transfer Protocol (FTP) File Transfer Protocol (FTP) - the protocol for exchanging files over the Internet. FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server (e.g., uploading a Web page file to a server). File Transfer Protocol (FTP) is the special language two computers use when copying or moving files between them.  Web Page Web Page – A web page is a single document that can be view on the web. A collection of web pages stored together with the same title is known as a web site.  Uniform Resources Locator The Uniform Resources Locator or URL, for short, is a standard for locating Internet documents. Each URL (also known as a web address) can be identified with only one Internet document (for e.g. a web page). A Uniform Resource Locator is found in the address bar. An example of a URL is http://www.thoughtpolice.com/bayboyz/1040.html protocol server address path To make the WWW really easy to use every resource on the web has a Uniform Reference Locator, or URL for short. Each page on the World Wide Web has a unique address; these addresses are called Uniform Resource Locators (URLs).  10/17/2023 http://www.macmillan-Caribbean.com/Products/CAPE-Maths-Unit-1.html. URL part Function http:// HTTP is a special language (protocol) that tells the web browser that this resource can be accessed using the Hypertext Transfer Protocol www The ‘www’ tells the browser that this is a web page macmillan-Caribbean.com This is the domain name and tells the web browser to contact the Macmillan Caribbean web server to obtain this resource. A domain name is a label that identifies a network /Products/ This describes the directory structure (where the document is stored) CAPE-Maths-Unit-1 This is the document’s name.html.html is the file type and indicates that the document was created SAMPLE FOOTER TEXT 79 10/17/2023 Group Work Consider these two URLs: https://cxc-store.com/csec-information-technology-syllabus-2010-2019-ebook.html http://www.macmillan-Caribbean.com/Products/CAPE-Maths-Unit-1.html Look at the URL and complete the URL #1 and URL #2 columns of the table. Examine both URLs carefully, noting similarities and differences. Are your findings in keeping with your expectations? Justify your response. URL #1 URL #2 Protocol Domain name Folder Filename File type (of web page) SAMPLE FOOTER TEXT 80 10/17/2023 Web Server A web server is a computer that delivers (serves up) web pages. When a request is made to access a website, the request is sent to the web server. The server then fetches the page and sends it to your browser. Web servers usually run on powerful computers dedicated to the task. When you type in a web address or click on a hyperlink, routers and switches direct your request to the correct web server. Web browsers and web servers use their own special language, Hypertext Transfer (or Transport) Protocol (HTTP), to communicate with each other. HTTP comes in two variations: HTTP and HTTPS. The ‘S’ in the second variation stands for secure and is used for applications like passwords and online banking. 10/17/2023 Upload When files are transferred to another computer they are sent or ‘uploaded’ by one computer and received or ‘downloaded’ by the other computer. Upload is a process of reading data from a user’s computer storage and sending it to another computer via communication channels. SAMPLE FOOTER TEXT 82 10/17/2023 Download Download is a process whereby programs or data are transferred via communications channels from a computer and stored on media located at the user’s computer. In simple terms you upload files TO another computer and download FROM the other computer. SAMPLE FOOTER TEXT 83 10/17/2023 Email Email The last key concept we will look at is email or electronic mail. Email replaces the traditional letter that is written on paper, addressed and delivered by the postal service. Electronic mail is mail or messages transmitted electronically by computers via a communications channel. It is usual for such messages to be held in a central store for retrieval at the user’s convenience.  Vlogging Vlogging is video blogging. As with a blog, users record personal stories and share them on video-hosting sites. Other users can then watch and comment.  Blogging Blogging – Blog is short for web log, and it is a kind of personal website. The blogger will post (that is, publish) entries at frequent intervals, giving their own thoughts on the issues and topics that concern them. Readers may also leave comments on any of the postings, so lively discussion can develop.  References Campbell, H., & Wood, A. (2020). Information Technology for CSEC Examinations (Third ed., pp. 37-39). 4 Crinan Street, United Kingston: Macmillan Education. Gay, G., & Blades, R. (2019). Information Technology CSEC (Third ed., pp. 62-70). : Oxford University Press.