Internet Classes

Internet Classes - Mastering the Internet, XHTML, and...

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Unformatted text preview: Mastering the Internet, XHTML, and JavaScript Chapter 1 Overview of the Internet Outline Goals and Objectives Chapter headlines Introduction Internet and WWW Client/Server Model Diagnostic commands Evolution of Internet Transmission IP Addresses and URLs Internet Domain Names E-mail addresses File Protocols File Compression and Decompression Intranets and Extranets Connecting to the Internet Types of Modems Internet Tools Summary Chapter 1 - Overview of the Internet 2 Goals and Objectives Goals Understand and master some of the basic concepts of Internet and World Wide Web, to be able to use them effectively in ordinary life, as well as in professional activities Objectives Client/Server Model Data and file transmission URLs and IP addresses E-mail addresses File protocols, compression and decompression Intranets and Extranets Internet connections Modems Chapter 1 - Overview of the Internet 3 Chapter Headlines 1.1 Introduction The Internet is dubbed as a new mode of transportation 1.2 The Internet and the World Wide Web The web is the section of internet that features multimedia capabilities 1.3 Internet Jargon Learn the internet jargon as you go 1.4 Client Server Model This model allows two networked computers to talk to each other 1.5 Client/Server Diagnostic Commands These are useful to probe communication with a server Chapter 1 - Overview of the Internet 4 Chapter Headlines 1.6 Evolution of the internet and the World Wide Web The internet has been evolving since the 1960s 1.7 Transmission across the Internet The TCP/IP protocol and its packets are central to internet use 1.8 IP Addresses and URLs Computers use IP addresses and humans use URLs 1.9 Internet domain Names An internet domain is a part of a URL 1.10 E-mail Addresses An E-mail address extends the naming scheme of a domain name Chapter 1 - Overview of the Internet 5 Chapter Headlines 1.11 File protocols on the Internet Formats and rules of exchanging files on the Internet 1.12 File Compression and Decompression Keeping file size small to speed up downloads and uploads 1.13 Intranets and Extranets Companies use these private networks for security reasons 1.14 Connecting to the Internet Companies use T lines while homes use dial-up connection 1.15 Types of Modems Analog (phone), cable, and DSL modems 1.16 Internet Tools These tools depend on you interest Chapter 1 - Overview of the Internet 6 Introduction The internet provides an instant mode of information and communication Internet had more users in its first five years than telephone did in its first thirty years E-mails already outnumbers regular mails Chapter 1 - Overview of the Internet 7 Internet and World Wide Web Internet is a network of networks It is known as information superhighway Internet links powerful servers in every part of the world World Wide Web (WWW) is the driving force of internet that features multimedia capabilities, such as, text, audio, video, graphics, and images The heart of internet is its dynamic nature and randomness of information Chapter 1 - Overview of the Internet 8 Client/Server Model Client/Sever model uses two computer programs installed on separate, but networked, computers located at different locations The client requests services from the server Multiple clients can access a server concurrently Chapter 1 - Overview of the Internet 9 Two-tier/Three-tier Architecture Client/Server databases are used extensively on web. Two-tier architecture is the most common model. In three-tier model, a middle server is added between the database and the client for security purposes. Chapter 1 - Overview of the Internet 10 Client/Server Diagnostic Commands The three important commands are: 1. finger: Allows you to find who is currently logged into a given host or whether a particular user is logged in e.g. finger hostname finger username@hostname 2. ping: Allows a client to check whether a server is up and running e.g. ping hostname 3. tracert: Traces the transmission route of data from client to a server e.g. tracert hostname Chapter 1 - Overview of the Internet 11 Evolution of the Internet Early research on the concept of internet began in 1962 at Advanced Research Project Agency (ARPA) The sequence of Internet development is: 1960s ARPANET 1970s-1980s CSNET, USENET, BITNET, NSFNET 1990s World Wide Web In 1989, WWW was conceived by Berner-Lee The Web exploded when Mosaic (first graphicallyoriented browser) became available from the NCSA Center at the University of Illinois, UrbanaChampaign in 1992 Chapter 1 - Overview of the Internet 12 Transmission across the Internet Data, such as Web pages and e-mail messages, are transmitted from one computer to another across the Internet via the TCP/IP protocol The TCP/IP protocol is embedded in TCP/IP software that is part of the OS (operating system) of any computer Each computer on the Internet has a unique IP address that is used to identify it. The TCP/IP software uses this IP address in data transmission Chapter 1 - Overview of the Internet 13 Transmission across the Internet The TCP/IP software breaks the data to be delivered into TCP packets (similar to letters), bundles them, labels them with the sender and receiver IP addresses (similar to envelopes), and sends them to the receiver's IP address The TCP/IP software of the receiving computer unpacks the TCP packets (similar to opening an envelope), connects them to construct the original data (such as an e-mail message), and makes it available for an application program to read (such as an e-mail tool) Chapter 1 - Overview of the Internet 14 The Internet Chapter 1 - Overview of the Internet 15 IP Addresses and URLs An IP address is a 32 bit integer represented by four 8-bit numbers, separated by periods A typical IP address is 155.33.227.141 An IP address is assigned to one and only one host A URL (uniform resource locator) is the name version of IP address A typical URL is http://www.neu.edu whose IP address is the one given above We use URLs because IP addresses are difficult to remember DNS (Domain Name System) software converts URLs to IP addresses and vice-versa. Chapter 1 - Overview of the Internet 16 URLs are also known as domain names Domain name consists of sub-domains (usually less than 5) The first sub-domain is host name The last sub-domain is top-level domain (TLD) Second level domain excludes the host name Example: Domain name Internet Domain Names www.coe.neu.edu Host name Second level domain name Chapter 1 - Overview of the Internet TLD 17 Internet Domain Names TLD can also be geographic i.e. country codes, such as `au' for Australia, `uk' for England, etc. The most common top-level domain names are .com: commercial organization .edu: educational institution .gov: government agency .org: nonprofit organization .net: network service provider .mil: U.S. military Chapter 1 - Overview of the Internet 18 E-mail Addresses Each user on the internet has a unique e-mail address The format of e-mail address is: username@second-levelDomainName The username in the format above is selected by the user and it can be a combination of letters, numbers and certain special characters Some example e-mail addresses are: a.smith@neu.edu zeid@coe.neu.edu a_smith@mit.edu smith01@harvard.edu Chapter 1 - Overview of the Internet 19 File Protocols File protocols determine the formats and rules of exchanging files between the server and client The file protocols used on the web are http: Allows client to request a webpage from server https: Secure http for secure communication smtp/pop/imap: Sends an e-mail message to a specified address nntp: Allows client to read and post messages on newsgroups ftp: Allows downloads and uploads for files telnet: Allows access to a remote computer file: Displays a file existing on client local drive Chapter 1 - Overview of the Internet 20 File Compression and Decompression File transfer through internet depends on internet connection speed, file size and server traffic. File size affects both transfer time and disk space File compression and decompression allow us to control the file size File compression softwares, e.g. winzip, use complex algorithms to decode (decompress) and encode (compress) a file. For example, the file "AAAAAAAGGGWZZZZ" can be compressed as "7A3G1W4Z" Multiple files can be compressed together to create archives that maintain file directory structure Chapter 1 - Overview of the Internet 21 Intranets and Extranets Intranet and Extranet are same as internet, the difference being in their geographical domains and level of security they use Intranet is a network that is contained within an organization. Outside intruders are not allowed to access this network Firewalls are installed around intranets for security Extranet is an organization network that allows access to outside networks Extranet may be viewed as an intermediate network between internet and intranet Chapter 1 - Overview of the Internet 22 Intranets and Extranets Chapter 1 - Overview of the Internet 23 Connecting to the Internet Internet Service Providers (ISPs) provide access to the internet by dial-up connection, DSL, or Cable connection AOL and MSN are ISPs who offer access and content Phone and cable companies are ISP who offer access only. Finding the content is users task Some ISP selection guidelines are: Maximum connection speed Type of connection (dial-up or broad band) Available help line Software provided Costs and charges Chapter 1 - Overview of the Internet 24 Types of Modems Modem is a device used to transfer data from one location to another through phone lines The types of modems are: Telephone (analog) modem Cable modem DSL and ADSL modem ISDN (digital) modem B-ISDN modem Satellite modem Wireless (cellular) modem Chapter 1 - Overview of the Internet 25 Internet Tools Internet tools allow effective use of the internet These tools are computer programs Some of these tools are shareware and the others are freeware The basic internet tools are: Web browsers Virus scan programs File compression and decompression programs FTP and Telnet programs Graphics programs Chapter 1 - Overview of the Internet 26 Summary The Internet and WWW are simple and enjoyable concepts to learn TCP/IP protocol and software transmit data (Web pages, e-mail messages) across the Internet Computers use IP addresses and humans use URLs DNS software provides URL-to-IP-address conversion Top-level domains: .com, .edu, .gov, .org, .net, and .mil E-mail addresses use username@DNS-domain format Intranets and Extranets are private networks Chapter 1 - Overview of the Internet 27 ...
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