Key Protocols Accessible On The Web


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Key Protocols Accessible On The Web

  1. 1. ELC 200 Day 3
  2. 2. Agenda <ul><li>Questions?? </li></ul><ul><li>Signed Contracts (4 miseing) </li></ul><ul><li>Finish Discussion on the World Wide Web </li></ul><ul><li>Begin discussion on Internet Architecture </li></ul><ul><li>Assignment 1 is Due </li></ul><ul><li>Quiz 1 on Sep 24 </li></ul><ul><ul><li>Chap 1 & 2 from text </li></ul></ul><ul><ul><li>45 min time limit, each extra min or fraction of a min will cost 3 points </li></ul></ul><ul><ul><li>20 M/C @ 4 points each </li></ul></ul><ul><ul><li>4 short essays @ 5 points each </li></ul></ul><ul><li>No class on Sep 27 </li></ul><ul><ul><li>I will post several discussion questions from Chap 3 & 4 on the evening of Sept 26 in the discussion boards in Blackboard </li></ul></ul><ul><ul><li>You must submit at least 2 answers and may submit up 4 answers </li></ul></ul><ul><ul><li>If you do not submit 2 answers, two points will taken from your quiz score total </li></ul></ul><ul><ul><li>+ 2 points will be added to your quiz score total for the first correct answer to every question. </li></ul></ul><ul><ul><li>+2 points for any student that submits 4 correct answers (they do not have to be first) </li></ul></ul><ul><ul><li>Only responses posted between 11 AM Sept 27 and 11 AM Sept 28 will graded </li></ul></ul><ul><li>Assignment 2 is posted (well ahead of schedule) </li></ul><ul><ul><li>Not due until Oct 4 </li></ul></ul>
  3. 3. Key Protocols Accessible on the Web <ul><li>E-mail - the protocol for e-mail is Simple Mail Transport Protocol, or SMTP </li></ul><ul><li>HTTP - Hypertext Transfer Protocol makes possible transmission of hypertext over networks </li></ul><ul><li>VoIP - Voice over Internet Protocol makes it possible to place a telephone call over the Web </li></ul>
  4. 4. Web Search Elements <ul><li>Internet contains millions of Web sites dedicated to tens of thousands of topics </li></ul><ul><li>Key elements that make the search process feasible: </li></ul><ul><ul><li>Browser </li></ul></ul><ul><ul><li>Plug-Ins </li></ul></ul><ul><ul><li>Search Engine </li></ul></ul>
  5. 5. The Browser (cont'd) <ul><li>A browser is a piece of software that allows users to navigate the Web </li></ul><ul><ul><li>Netscape Navigator </li></ul></ul><ul><ul><li>Microsoft Internet Explorer </li></ul></ul><ul><ul><li>Firefox </li></ul></ul><ul><ul><li>Opera </li></ul></ul><ul><ul><li>Winwap </li></ul></ul>
  6. 6. The Browser (cont'd) <ul><li>A browser is a Web client program that uses Hypertext Transfer Protocol (HTTP) to make requests of Web servers throughout the Internet on behalf of the browser user </li></ul><ul><ul><li>Text-only mode such as Lynx </li></ul></ul><ul><ul><li>Graphic mode involves a graphical software program that retrieves text, audio, and video </li></ul></ul>
  7. 7. Plug-Ins <ul><li>Software programs configured to a Web browser to improve its capabilities </li></ul><ul><li>Working together with plug-ins, browsers today offer seamless multimedia experiences </li></ul><ul><li>A popular plug-in on the Web is Adobe Acrobat Reader </li></ul><ul><li>Microsoft developed software called Active X, which makes plug-ins unnecessary </li></ul><ul><ul><li>This software makes it possible to embed animated objects and data on Web pages </li></ul></ul><ul><ul><li>Being a Microsoft product, Active X works best with Microsoft’s Internet Explorer browser </li></ul></ul>
  8. 8. Multimedia <ul><li>Since 1999, it is now common to use the Web to listen to audio and watch video - prerecorded or live off the Internet </li></ul><ul><li>Streaming media is audio or video that begin to play as it downloads (streaming), done through buffering </li></ul><ul><ul><li>Buffering is used to minimize the wait time between downloading and actual viewing of the material </li></ul></ul><ul><li>RealPlayer and Windows Media Player are alternative options for the broadcast of real-time (live) events </li></ul><ul><li>Shockwave is multimedia software that allows for an entire multimedia display of audio, graphics, animation, and sound </li></ul><ul><li>Live Cam software essentially is a video camera that digitizes images and transmits them in real time to a Web server </li></ul><ul><li>Chat programs make it convenient for people to “talk” to each other in real time by typing messages and receiving responses (i.e. America Online’s Instant Messenger) </li></ul>
  9. 9. The Search Engine <ul><li>A search process begins with a search engine: </li></ul><ul><li>a Web site or a database, along with the tools to generate that database and search its contents for “keywords” that describe what you’re looking for. </li></ul>
  10. 10. Other Definitions for Search Engines <ul><ul><li>A software program that collects and indexes Internet resources and provides a keyword search system allowing the user to identify and retrieve resources based on words, phrases, or patterns within those documents </li></ul></ul><ul><ul><li>A Web-based system for searching the information available on the Web </li></ul></ul><ul><ul><li>An automated system that relies on a software agent (otherwise known as spiders, robots or crawlers) that explores the World Wide Web following links from site to site and catalogs relevant text and content, storing Web pages and creating a customized index based on the user’s query of the search engine’s database </li></ul></ul>
  11. 11. More on Search Engines <ul><li>Two main elements of Web research are indexes and search engines </li></ul><ul><li>An index can help a searcher acquire general information or gain a feel for the general topic </li></ul><ul><ul><li> </li></ul></ul><ul><li>An index can be hierarchical or alphabetical </li></ul><ul><ul><ul><li>Hierarchical indexing leads from general to specific topics </li></ul></ul></ul><ul><ul><ul><li>Alphabetical indexing contains sources that focus on a specific topic or area of concern </li></ul></ul></ul>
  12. 12. Other Components of a Web Search Engine <ul><li>A spider is a program that roams the Web from link to link, identifying and scanning pages </li></ul><ul><li>A spider is software unique to a search engine that allows users to query the index and returns results in relevancy-ranked order (alphabetical) </li></ul><ul><li>Search Engine Improvements: </li></ul><ul><ul><li>First-generation search engine returns results in schematic order, constructing a term relevancy rating of each hit and presenting search results in this order, also called “on the page” ranking. </li></ul></ul><ul><ul><li>Second-generation search engine organizes search results by peer ranking concept, domain, or site rather than by relevancy, also called “off the page” information. </li></ul></ul>
  13. 13. Search Facts to Remember <ul><li>People look up Web sites with search engines. </li></ul><ul><li>People usually use bookmarks to visit their favorite Web sites. </li></ul><ul><li>A Web site must be quick and current. </li></ul><ul><li>A Web site should address the privacy and navigation concerns of the user. </li></ul><ul><li>The “bottleneck” problem </li></ul><ul><li>People are reluctant to pay to surf a Web site. </li></ul>
  14. 14. Search Engines Are Getting Smarter <ul><li>Experts are working feverishly at making search engines more intelligent </li></ul><ul><li>An example of incorporating “intelligence” into search engines is a software agent called Query Tracker that supplements a user’s query with its own, and it gains in performance with prolonged use and feedback. </li></ul><ul><li>Another intelligent search engine application is IBM’s WebFountain that determines whether an entity is a person’s name, a corporate logo, a product, or a discount and then goes ahead and attaches a metadata tag to it. </li></ul><ul><li>On the drawing board is “thinking in pictures” as an alternative way to search the Web </li></ul>
  15. 15. Query Tracker Source: Adapted from Anthes, Gary H., “Search For Tomorrow” Computerworld, April 5, 2004, 26.
  16. 16. Search Engine Optimization <ul><li>A way of trying to increase the number of visitors to a Web site by ranking high in the search results displayed by a search engine </li></ul><ul><li>One way to optimize is via hyperlinks </li></ul>
  17. 17. Tips for Search Engine Optimization <ul><li>General keywords are nowhere as good as specific keyword phrases </li></ul><ul><li>Check the Web site of the competition for ideas </li></ul><ul><li>Think of what visitors would search for in the page you’re optimizing </li></ul><ul><li>Include the most important keyword phrases in heading tags on your page </li></ul><ul><li>Finalize the list of keyword phrases for the pages you optimize </li></ul><ul><li>The title tag of your page is the most important factor to consider </li></ul><ul><li>Visitors as well as search engines read your pages by looking at keywords to see what you have to offer </li></ul><ul><li>Many people have a false impression that good metatags are all that is needed to achieve good listings in the search engine </li></ul><ul><li>There are two metatags that can help in listing your Web site: meta keywords and meta descriptions </li></ul>
  18. 18. Meta tags <title> Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more</title> <meta name=&quot;description&quot; content=&quot;Online shopping from the earth's biggest selection of books, magazines, music, DVDs, videos, electronics, computers, software, apparel & accessories, shoes, jewelry, tools & hardware, housewares, furniture, sporting goods, beauty & personal care, broadband & dsl, gourmet food & just about anything else.&quot; /> <meta name=&quot;keywords&quot; content=&quot;Amazon,, Books, Online Shopping, Book Store, Magazine, Subscription, Music, CDs, DVDs, Videos, Electronics, Video Games, Computers, Cell Phones, Toys, Games, Apparel, Accessories, Shoes, Jewelry, Watches, Office Products, Sports & Outdoors, Sporting Goods, Baby Products, Health, Personal Care, Beauty, Home, Garden, Bed & Bath, Furniture, Tools, Hardware, Vacuums, Outdoor Living, Automotive Parts, Pet Supplies, Broadband, DSL&quot; /> </head>
  19. 19. Internet Service Providers <ul><li>Internet service provider (ISP) is a company that links users to the Internet for a fee </li></ul><ul><li>Services offered by ISPs </li></ul><ul><ul><li>Linking consumers and businesses to the Internet </li></ul></ul><ul><ul><li>Monitoring and maintaining customers’ Web sites </li></ul></ul><ul><ul><li>Providing network management and system integration </li></ul></ul><ul><ul><li>Providing backbone access services for other ISPs (like PSI and UUNET) </li></ul></ul><ul><ul><li>Offering payment systems for online purchases </li></ul></ul>
  20. 20. Internet Service Providers (cont'd) <ul><li>Initially, the cost for Internet access often exceeded $1,000 per month </li></ul><ul><li>Many of today’s ISPs offer unlimited access for as low as $5 per month </li></ul><ul><li>Many local governments are funding the use of the Internet because of its political, educational, and commercial benefits </li></ul><ul><li>The problem for some ISPs is sudden growth without advance planning to accommodate that growth </li></ul><ul><li>A well managed ISP requires: </li></ul><ul><ul><li>Professional management </li></ul></ul><ul><ul><li>A highly skilled technical staff </li></ul></ul><ul><ul><li>Healthy budget to bring the technology in line with the voracious </li></ul></ul><ul><ul><li>Ensure a balance between creativity and control and between managing growth and a stable technical infrastructure appetite of today’s consumer </li></ul></ul>
  21. 21. Stability and Reliability of the Web <ul><li>No one single agency or company owns the Internet </li></ul><ul><li>Each company on the Internet owns its own network </li></ul><ul><li>Links between these companies and the Internet are owned by telephone companies and ISPs </li></ul><ul><li>The organization that coordinates Internet functions is the Internet Society </li></ul><ul><li>Internet is designed to be indefinitely extendable </li></ul><ul><li>Reliability depends primarily on the quality of service providers’ equipment </li></ul>
  22. 22. Web Fundamentals <ul><li>The WWW is a global network of millions of Web servers and Web browsers connected by the hypertext transfer protocol (HTTP) </li></ul><ul><li>The WWW is a giant client/server system </li></ul><ul><ul><li>Content is held by Web servers and requested by clients or browsers </li></ul></ul><ul><ul><li>Clients display the information sent by the Web server on their monitors </li></ul></ul><ul><ul><li>Web servers provide pages of multimedia information in seconds </li></ul></ul><ul><ul><li>The most important element of a Web site is its links to other pages within the site or across sites </li></ul></ul>
  23. 23. Web Fundamentals - URLs and HTTP <ul><li>Uniform Resource Locators (URLs) are central to the Web in e-commerce </li></ul><ul><li>A URL such as consists of two key parts: </li></ul><ul><ul><li>http:// (Hypertext Transport Protocol) is a protocol designator </li></ul></ul><ul><ul><li> is the server name: </li></ul></ul><ul><ul><ul><li>www after the double slash tells the network that the material requested is located on a dedicated Web server </li></ul></ul></ul><ul><ul><ul><li>Virginia is the name of the Web site requested </li></ul></ul></ul><ul><ul><ul><li>Edu is a code for the domain of the Web server indicating that the site is an edu cational institution </li></ul></ul></ul>
  24. 24. Security Protocols <ul><li>Two main security protocols </li></ul><ul><ul><li>Secure Sockets Layer (SSL) is a protocol for transmitting private information in a secure way over the Internet </li></ul></ul><ul><ul><li>Secure HTTP (S-HTTP) provides various security features such as client/server authentication and allows Web clients and servers to specify privacy capabilities </li></ul></ul><ul><li>Security is a major concern </li></ul>
  25. 25. Key Terms for Internet Literacy <ul><li>Internet service provider (ISP) is a company that links users to the Internet for a fee; the entrance ramp to the Internet. </li></ul><ul><li>A Browser is a software program loaded on a PC that allows you to access or read information stored on the Internet. It is the client program that enables you to interface with the Internet. </li></ul><ul><li>Server is the destination point on the Internet where the information you are seeking is stored. </li></ul><ul><li>Electronic mail (e-mail) is probably the most popular and abused network application across all user categories. </li></ul>
  26. 26. Key Terms for Internet Literacy (c ont’d ) <ul><li>File transfer protocol (FTP) is a standard protocol that allows you to copy files from computer to computer </li></ul><ul><li>Telnet is a basic Internet protocol that allows you to log on to a computer and access files from a remote location as if they were local files </li></ul><ul><li>Bulletin board systems (BBS) is a computer-based meeting and announcement system that allows local people to exchange information free of charge. A BBS generally has a simple interface to the Internet for users to access services like e-mail and NetNews. </li></ul>
  27. 27. Key Terms for Internet Literacy (cont'd) <ul><li>Web pages are written in a language called Hypertext Markup Language (HTML) </li></ul><ul><ul><li>Language specifies display features that visually structure a page </li></ul></ul><ul><ul><li>Best known for publishing static information (flows in one direction) </li></ul></ul><ul><li>How to allow the user to interact with a Web site? </li></ul><ul><ul><li>Common gateway interface (CGI) scripts execute a process on the server. When executed, the script passes data (posted form) provided by the customer for verification and action. </li></ul></ul><ul><ul><li>Java programming language or Java makes it possible for the customer to interact directly with the program on the screen. </li></ul></ul>
  28. 28. Managerial Implications <ul><li>The Web has changed the way business and information technology work together. </li></ul><ul><li>E-commerce is transforming the Internet from a “browse-and-surf” environment into a mammoth information exchange. </li></ul><ul><li>The important thing is to keep an eye on the technologies, as they evolve, and to be familiar with the changes before taking a dive into the Internet. </li></ul><ul><li>Strategize first, test the waters, and be sure you have a unique product supported by qualified staff to follow up on the Web traffic that it attracts. </li></ul>
  29. 29. Chapter Summary <ul><li>The Web is the fastest growing, most user-friendly, and most commercially popular technology to date. </li></ul><ul><li>The Internet owes its existence to the Pentagon, where it originally was created for military research. </li></ul><ul><li>The Internet is physically hierarchical. High-speed backbones are at the top, with regional and individual networks at the bottom. </li></ul><ul><li>Internet service providers link commercial traffic to its destination. </li></ul>
  30. 30. Chapter Summary (cont’d) <ul><li>The Internet has many uses; it also has many limitations. </li></ul><ul><li>World Wide Web is a global hypertext network of millions of Web servers and browsers connected by hypertext transfer protocol (HTTP) and its many derivatives. </li></ul><ul><li>It is important to learn the language of the Internet before starting an e-commerce project. </li></ul><ul><li>The Internet and the Web have changed the way business and technology work together. </li></ul>
  31. 31. Internet Architecture
  32. 32. The focus of this chapter is on several learning objectives <ul><li>Types of networks required to conduct e-commerce </li></ul><ul><li>The technical backbone behind accessing information on Web sites </li></ul><ul><li>How information is transferred between a customer’s browser and a Web site on the Internet </li></ul><ul><li>How a message is handled in transit on the Internet </li></ul><ul><li>Hardware and software requirements to support a Web site for e-commerce </li></ul><ul><li>Factors to consider in designing and managing networks </li></ul>
  33. 33. Building Blocks of Electronic Commerce
  34. 34. Internet Basics <ul><li>The Internet is a network of networks </li></ul><ul><ul><li>Network is any-to-any communications </li></ul></ul><ul><li>Each station on the network has a unique address (much like a phone number) called an IP address </li></ul><ul><li>Routers and switches forward traffic between network segments </li></ul><ul><li>Protocols are rules that govern the way a network operates: </li></ul><ul><ul><li>How data travel in packets </li></ul></ul><ul><ul><li>How electrical signals represent data on a network cable </li></ul></ul>
  35. 35. What Is a (computer) Network? <ul><li>A connection between at least two computers for the purpose of sharing resources </li></ul><ul><li>All networks are based on the concept of sharing </li></ul><ul><ul><li>Why connect if you don’t share? </li></ul></ul>
  36. 36. Types of Networks <ul><li>Peer-to-Peer Networks are the linking of several PCs so that each acts as a peer, sharing and exchanging information without the need for a centralized server </li></ul><ul><li>Client / Server Networks are a cluster of computers (called clients) connected to one or more servers to form a network </li></ul>
  37. 37. Peer-to-Peer Networks <ul><li>Computers are linked together as equals </li></ul><ul><li>No centralized server or control </li></ul><ul><li>Any computer can share its resources with any other computer on the same network in any way and whenever it chooses </li></ul><ul><li>Users are network administrators in that they control access to the resources residing on their own computer </li></ul><ul><li>Can result in institutionalized chaos, and security can be a problem </li></ul>
  38. 38. Peer-to-Peer Networks ( cont'd ) <ul><li>Setup usually connects fewer than 10 computer </li></ul><ul><li>As the number of users increases, the peer-to-peer environment becomes impractical </li></ul><ul><li>Most common </li></ul><ul><ul><li>AppleTalk </li></ul></ul><ul><ul><li>NetBios </li></ul></ul>
  39. 39. Basic Peer-to-Peer Network
  40. 40. Pros and Cons of Peer-to-Peer Network
  41. 41. Client/Server Networks <ul><li>A server is simply a special-purpose computer designed to address a client’s requests </li></ul><ul><li>A client is any computer or workstation connected to the server within a network </li></ul><ul><li>All programs or applications reside on the server </li></ul><ul><li>The client downloads software and/or data from the server </li></ul><ul><li>When the client finishes data may be uploaded back to the server </li></ul>
  42. 42. Client/Server Network
  43. 43. Pros and Cons of Client/Server Network
  44. 44. IP Addresses <ul><li>A Web site’s address includes the name of the host computer’s link the Web site resides on </li></ul><ul><li>Each host is identified by a unique host number (called an IP address) and by a name that is easier to remember than the number </li></ul>
  45. 45. IP Address Arithmetic <ul><li>An IP address consists of 32 binary digits or bits (zeros and ones) </li></ul><ul><li>Divide the 32 bits into 4 groups of 8 bits called a byte, or octet </li></ul><ul><li>Each octet represents a decimal value from 0 through 255 </li></ul><ul><li>Write the four decimal values separated by dots </li></ul><ul><li> - computer friendly, but not human friendly </li></ul><ul><li>Every host on the Internet has a host number </li></ul><ul><li>My address (use scientific calculator in XP) </li></ul><ul><ul><li> </li></ul></ul><ul><ul><li>10000010.01101111.01000010.11110000 </li></ul></ul><ul><ul><li>10000010011011110100001011110000 </li></ul></ul>
  46. 46. Host Naming <ul><li>A host name is an Internet address consisting of text labels separated by dots </li></ul><ul><li>Host name is people friendly </li></ul><ul><li>Host names used instead of IP addresses or host numbers </li></ul><ul><ul><li>Wouldn’t it be great if the phone system worked this way? </li></ul></ul><ul><ul><ul><li>Why isn’t it? </li></ul></ul></ul>
  47. 47. Networks and Numbers <ul><li>Host number divided into two parts </li></ul><ul><ul><li>Network part - 2 octets </li></ul></ul><ul><ul><li>Local part - 2 octets </li></ul></ul><ul><ul><li>University of Virginia host number </li></ul></ul><ul><ul><li>191 . 170 . 64 . 12 </li></ul></ul><ul><ul><li>network local </li></ul></ul><ul><ul><li>part part </li></ul></ul><ul><ul><li>All UVa addresses begin with 191 . 170 </li></ul></ul><ul><ul><ul><li>UMS is 130.111 </li></ul></ul></ul><ul><ul><li>64 identifies a subnet at UVa </li></ul></ul><ul><ul><li>12 is the machine on the subnet </li></ul></ul>{ {
  48. 48. Networks and Sizes <ul><li>Networks are classified in three sizes: </li></ul><ul><ul><li>Class A (large) </li></ul></ul><ul><ul><li>Class B (medium) </li></ul></ul><ul><ul><li>Class C (small) </li></ul></ul><ul><ul><li>Class D is a multicast network </li></ul></ul><ul><li>The initial bits of the IP address tells the size of the network host </li></ul>
  49. 49. IP Address Classes WRONG! 3,720,183,052                       532,676,100   254   2,097,150 Class C 1,073,577,988   65,534   16,382 Class B 2,113,928,964   16,777,214   126 Class A total   # Hosts / network   # of networks              
  50. 50. Class A Networks <ul><li>A host is in a Class A network if the first bit of the first octet is 0 </li></ul><ul><li>0 xxxxxxx </li></ul><ul><li>Class A network host number format </li></ul><ul><li>NNN.LLL.LLL.LLL NNN = network part </li></ul><ul><li> LLL = local part </li></ul><ul><li>There are 7 bits left in the first octet for network host number - 126 Class A networks (2 16 ) </li></ul><ul><ul><li>The part in the text is wrong also! </li></ul></ul><ul><li>The remaining three octets are for the local host id on the network - 16 million local hosts (2 24 ) </li></ul>
  51. 51. Class B Networks <ul><li>A host is in a Class B network if the first two bits of the first octet are 10 </li></ul><ul><li>10 xxxxxx </li></ul><ul><li>Class B network host number format </li></ul><ul><li>NNN.NNN.LLL.LLL NNN = network part </li></ul><ul><li>LLL = local part </li></ul><ul><li>There are 14 bits left in the first two octets for network host number - 16000 Class B networks (2 14 ) </li></ul><ul><li>The remaining two octets are for the local host id on the network - 65000 local hosts (2 16 ) </li></ul>
  52. 52. Class C Networks <ul><li>A host is in a Class C network if the first three bits of the first octet are 110 </li></ul><ul><li>110 xxxxx </li></ul><ul><li>Class C network host number format </li></ul><ul><li>NNN.NNN.NNN.LLL NNN = network part </li></ul><ul><li>LLL = local part </li></ul><ul><li>There are 21 bits left in the first three octets for network host number - 2 million Class C networks (2 21 ) </li></ul><ul><li>The remaining one octet is for the local host id on the network - 254 local hosts (2 8 ) </li></ul><ul><ul><li>[Note: 2 8 = 256, however, two of the local host ids are reserved] </li></ul></ul>
  53. 53. Class D Networks <ul><li>A host is in a Class D network if the first four bits of the first octet are 1110 </li></ul><ul><li>1110 xxxx </li></ul><ul><li>Used for multicasting </li></ul><ul><li>The packet goes to all hosts on that subnet. </li></ul>
  54. 54. Network Class Example <ul><li>UVa network host number is </li></ul><ul><li>Binary representation for the 191 is </li></ul><ul><li>10111111 </li></ul><ul><li>First two bits are 10 -> Class B network </li></ul><ul><li>UVa is a class B network </li></ul><ul><ul><li>65,000 possible hosts in UVa network (2 16 ) </li></ul></ul>
  55. 55. Network Class Example <ul><li>UMS network host number is </li></ul><ul><li>Binary representation for the 130 is </li></ul><ul><li>10000010 </li></ul><ul><li>First two bits are 10 -> Class B network </li></ul><ul><li>UMS is a class B network </li></ul><ul><ul><li>65,000 possible hosts in UMS network (2 16 ) </li></ul></ul>
  56. 56. Zones and Domain Names <ul><li>An Internet name is decoded from right to left </li></ul><ul><li>Zone name is the last (rightmost) part of a domain name preceded by a dot, specifying the type of domain name </li></ul><ul><li>Zones are classified in two ways: </li></ul><ul><ul><li>Three-letter zone names </li></ul></ul><ul><ul><li>Two-letter zone names </li></ul></ul><ul><li>Domain name is a Web address that contains two or more word groups separated by periods </li></ul><ul><li> => domain name </li></ul><ul><li> .com => zone </li></ul>
  57. 57. Sample Zone Names
  58. 58. Common Geographical Two-Letter Zone Names
  59. 59. How to Pick a Domain Name <ul><li>Pointer for picking domain names </li></ul><ul><ul><li>If you sell bricks, pick a domain name containing a word like brick </li></ul></ul><ul><ul><li>Consider name length and ease of remembering the name </li></ul></ul><ul><ul><li>Hyphens to force search engines to see keywords in your domain name </li></ul></ul><ul><ul><li>Make sure the domain name is easy for Web users to remember and find </li></ul></ul><ul><ul><li>The domain name should suggest the nature of your product or service </li></ul></ul><ul><ul><li>The domain name should serve as a trademark </li></ul></ul><ul><ul><li>The domain name should be free of legal conflicts </li></ul></ul>
  60. 60. How to Register a Domain Name <ul><li>Check if the domain name you propose has been taken </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li>One of the most popular and reliable registration sites is </li></ul><ul><ul><li>I use </li></ul></ul>
  61. 61. Packets and Protocols <ul><li>All data sent through the Internet are sent as packets </li></ul><ul><li>A packet is a sequence of bits that carries identifying information for transmitting the data as well as the data itself </li></ul><ul><li>A single packet contains a header to keep track of the actual data it carries </li></ul><ul><li>Packets range in size from 100 bytes to 2,000 bytes </li></ul><ul><li>Messages that are larger than the standard packet size are split into a series of packets for transmission </li></ul>
  62. 62. Packets and Internet Protocols <ul><li>Protocols are pieces of software that run on every node or computer and allow every pair of computers to communicate directly without having to know much about each other, except for the IP address </li></ul><ul><li>Protocols govern communication between peer processes on different systems </li></ul><ul><li>Differing client browser and Web server </li></ul><ul><li>Protocols used in connection with the Internet include many functions and the TCP/IP protocol suite </li></ul>
  63. 63. Packet Switching <ul><li>The way data are exchanged between two communicating computers </li></ul><ul><li>Divides data into packets (datagrams), which also contain control information like Internet addresses of the source and destination computers </li></ul><ul><li>Packet switching makes it possible to enable multiple communicating computers to share the network efficiently, quickly, and accurately </li></ul>
  64. 64. OSI Reference Model <ul><li>Application Layer </li></ul><ul><li>Presentation Layer </li></ul><ul><li>Session Layer </li></ul><ul><li>Transport Layer </li></ul><ul><li>Network (Internet) Layer </li></ul><ul><li>Data Link Layer </li></ul><ul><li>Physical Layer </li></ul>
  65. 65. OSI Reference Model - ( cont’d ) <ul><li>A seven-layer model that defines the basic network functions </li></ul><ul><li>Each layer handles a different portion of the communications process with specific network functions </li></ul>
  66. 66. ISO 7-layer Model Node A Node B Data translation MIME, encryption, etc. User applications FTP, email, browser, etc. End-to-End control Error correction (TCP) Link management MAC, physical addressing Session management Dialog management, security Manages data transfer Message routing (IP) Physical hardware Media, signal transmission Messages Messages Messages Messages Packets Frames Bits on physical medium Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Layer 3 Network Layer 2 Data Link Level 1 Physical Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Layer 3 Network Layer 2 Data Link Level 1 Physical
  67. 67. Application Layer <ul><li>Communicates with the actual application in use </li></ul><ul><li>Standards at the application layer specify how two application programs should communicate </li></ul><ul><ul><li>The main standard hypertext transfer protocol (HTTP) </li></ul></ul><ul><ul><li>Hypertext markup language (HTML) is a standard set of codes representing text or graphics </li></ul></ul><ul><li>The application layer is where the user begins to do something useful </li></ul><ul><li>Simple network management protocol (SNMP) is a protocol that controls network devices at the application layer </li></ul><ul><li>Domain naming service (DNS) is software that converts IP addresses into easy-to-remember names for the user </li></ul>
  68. 68. Presentation and Session Layers <ul><li>Presentation Layer </li></ul><ul><ul><li>The network’s translator </li></ul></ul><ul><ul><li>Converts data into a format for network transmission and converts incoming data into a format the receiving application can understand </li></ul></ul><ul><li>Session Layer </li></ul><ul><ul><li>Facilitates a “session” between two parties to communicate across a network </li></ul></ul><ul><ul><li>Keeps track of the status of the exchange and ensures that only designated parties are allowed to participate </li></ul></ul><ul><ul><li>Enforces security protocols </li></ul></ul>
  69. 69. Transport Layer <ul><li>Manages the transmission or flow of data between two computers or across a network </li></ul><ul><li>Manages the data flow is by segmenting data into multiple packets </li></ul><ul><li>Acknowledges successful transmissions and requests retransmission if packets are damaged or arrive in error </li></ul><ul><li>Breaks the connection when transmission ends </li></ul><ul><li>Standard for the transport layer is the transmission control protocol (TCP) </li></ul>
  70. 70. Network (Internet) Layer <ul><li>Routes messages across multiple nodes </li></ul><ul><li>Handles network congestion </li></ul><ul><li>Standard for routing packets is the Internet Protocol (IP) </li></ul><ul><li>Resends lost packets automatically </li></ul><ul><li>Defines how data are subdivided into packets </li></ul>
  71. 71. Data Link Layer <ul><li>The “basement” of the Internet </li></ul><ul><li>Messages at the data link layer are called data frames the basic unit of Internet traffic </li></ul><ul><li>Another way of sending packets is over an Ethernet </li></ul><ul><ul><li>Framing and error detection are handled automatically by Ethernet hardware </li></ul></ul><ul><ul><li>Ethernet broadcasts a message to all the computers linked to it, but only the computer with the right address broadcasts an answer </li></ul></ul>
  72. 72. Physical Layer <ul><li>Lowest layer in the journey of a message from source to destination </li></ul><ul><li>Converts bits into signals for outgoing messages and signals into bits for incoming messages </li></ul>
  73. 73. Other Networks <ul><li>TCP/IP protocols are not restricted to the Internet </li></ul><ul><li>Companies have found TCP/IP useful for: </li></ul><ul><ul><li>Creating intranets, or internal company networks </li></ul></ul><ul><ul><li>Forming extranets to connect with vendors and suppliers and establish shared databases </li></ul></ul>
  74. 74. Network Cable Types <ul><li>Network connectivity means: </li></ul><ul><ul><li>Speed of data transfer </li></ul></ul><ul><ul><li>Network size </li></ul></ul><ul><ul><li>Ease of installation </li></ul></ul><ul><li>There are three types of cable </li></ul><ul><ul><li>Twisted pair </li></ul></ul><ul><ul><li>Optical fiber </li></ul></ul><ul><ul><li>Coaxial </li></ul></ul><ul><ul><li>Wireless technology </li></ul></ul>
  75. 75. Twisted-Pair Cable <ul><li>Two pairs of insulated wires twisted around each other, even enclosed in a plastic sheath </li></ul><ul><li>The most commonly used type of networking cable in the </li></ul><ul><li> United States </li></ul><ul><li>Originally used to connect a telephone to a wall jack </li></ul><ul><li>Least expensive cable medium </li></ul><ul><li>Shielded and unshielded twisted pair </li></ul><ul><ul><li>Unshielded twisted-pair (UTP) cabling does not have shielding against electrical interference </li></ul></ul><ul><ul><li>Shielded twisted-pair (STP) cabling has an electrically grounded woven copper mesh or aluminum foil wrapped around each twisted pair and another metal mesh wrapped around a multiple bundle of wires to reduce electromagnetic interference </li></ul></ul>
  76. 76. UTP Cable
  77. 77. Fiber-Optic Cable <ul><li>Uses light rather than voltage to carry data </li></ul><ul><li>Fiber enables digitized light signals to be transmitted more than 60 miles without being amplified </li></ul><ul><li>Outperforms copper and coaxial media with fewer transmission losses, lower interference, and higher bandwidth </li></ul><ul><li>Drawbacks are: </li></ul><ul><ul><li>It is the most expensive of all network media types </li></ul></ul><ul><ul><li>Each segment that transmits incoming and receiving data must contain an incoming cable and an outgoing cable </li></ul></ul><ul><ul><li>It requires highly skilled installers and special connectors </li></ul></ul>
  78. 78. Optical Fiber
  79. 79. Optical Fiber Source: Adapted from Panko, Raymond, Business Data Communications and Networking (3 rd ed.), Upper Saddle River, NJ: Prentice-Hall, 2001, p. 278.
  80. 80. Fiber Optic Selection Criteria <ul><li>Attenuation or delay, the reduction of signal strength due to gravitational pull </li></ul><ul><li>Dispersion , the time distortion of an optical signal that results from discrete wave-length components traveling at different rates </li></ul><ul><li>Mode-field diameter (MFD) , the functional parameter that determines optical performance when a fiber is coupled to a light source, spliced, or bent </li></ul>
  81. 81. Coaxial Cable <ul><li>An early version of the way computers were connected to a network </li></ul><ul><li>The cable in cable TV </li></ul><ul><li>Has a copper core that is much thicker than twisted-pair cable, so it allows higher data transmission rates over long distances </li></ul><ul><li>Transmits up to 10 Mbps for a distance of up to 500 meters </li></ul><ul><li>Main drawback is its inflexibility and low security </li></ul>
  82. 82. Coaxial Cable
  83. 83. Wireless Technology <ul><li>Data communication without physical attachments </li></ul><ul><li>Three types of wireless data transmission technology: </li></ul><ul><ul><li>Microwave transmission is used to connect LANs in separate buildings that must be within the line of sight of each other </li></ul></ul><ul><ul><li>Radio technology by radio frequency with no distance limitations </li></ul></ul><ul><ul><li>Infrared transmission operates at frequencies approaching the speed of light </li></ul></ul>
  84. 84. Network Components <ul><li>Network Interface Card </li></ul><ul><ul><li>A card installed in a slot in the PC to allow communication between the PC and other PCs in the LAN and beyond </li></ul></ul><ul><ul><li>To communicate over a telephone line the PC needs a modem, a device that converts digital signals into analog format for outgoing transmission and converts incoming messages from analog to digital format for computer processing </li></ul></ul><ul><li>Hubs and Switches </li></ul><ul><ul><li>Hub is a piece of hardware that operates at the OSI physical layer and acts as a connecting point </li></ul></ul><ul><ul><li>Switch is a piece of hardware that offers a direct connection to a particular PC </li></ul></ul>
  85. 85. Network Components (cont'd) <ul><li>Routers </li></ul><ul><ul><li>A piece of hardware that operates at the OSI Internet layer, linking the network into little chunks called network segments </li></ul></ul><ul><ul><li>Usually “intelligent” and evaluate the network traffic and can stop local traffic from entering and causing congestion </li></ul></ul><ul><ul><li>Make intelligent path choices </li></ul></ul><ul><ul><li>Filter out packets that need not be received </li></ul></ul><ul><ul><li>Expensive and difficult to operate </li></ul></ul><ul><li>Gateways </li></ul><ul><ul><li>A special-purpose computer that allows communication between dissimilar systems on the network </li></ul></ul>
  86. 86. Network Design Considerations STEP 1: Factors to Keep in Mind <ul><li>Location - Where will the network be installed? </li></ul><ul><li>Capacity - What is the optimum traffic capacity of the network? </li></ul><ul><li>Distance Limitations - What is the distance of the farthest PC to the server? </li></ul><ul><li>Cost - What is the estimated cost of the proposed network installation? </li></ul><ul><li>Potential Growth - How easily and how well can the network be scaled to meet growing demands? </li></ul><ul><li>Security - How secure is the proposed network? </li></ul>
  87. 87. Network Design Considerations STEP 2: Hardware and Software Considerations <ul><li>Hardware Requirements </li></ul><ul><li>Software Requirements </li></ul><ul><li>Disaster Recovery and Fault-Tolerance Requirements </li></ul>
  88. 88. Network Design Considerations SUCCESSFUL INSTALLATION <ul><li>Conduct a survey of current technology and constraints </li></ul><ul><li>Document network requirements </li></ul><ul><li>Decide on the network operating systems </li></ul><ul><li>Decide on the file server hardware platform </li></ul><ul><li>Determine the physical environment and client support </li></ul>
  89. 89. Managerial Factors <ul><li>Network management tasks: </li></ul><ul><ul><li>Maintain an acceptable level of system availability </li></ul></ul><ul><ul><li>Assure good response time </li></ul></ul><ul><ul><li>Run the network at optimal capacity </li></ul></ul><ul><ul><li>Route voice and data traffic around the clock </li></ul></ul><ul><ul><li>Enable managers, employees, and customers to communicate effectively regardless of time, distance, or location </li></ul></ul>
  90. 90. Managerial Factors – ( cont’d ) <ul><li>Key components of a typical network management system: </li></ul><ul><ul><li>The manager - the network administrator manages the network via software loaded on a special workstation </li></ul></ul><ul><ul><li>Managed nodes - the manager monitors nodes or pieces of software call agents that communicate with the manager on behalf of the node </li></ul></ul><ul><ul><li>Objects - Ports on the managed node that the agent represents to the manager </li></ul></ul><ul><ul><li>Management Information Base (MIB) - software that defines the objects that can exist, based on the initial design of the database </li></ul></ul><ul><ul><li>Requests and Responses - uses SNMP to allow the manager and agents to work through pre-established cycles </li></ul></ul>
  91. 91. E-Commerce Issues <ul><li>Financial Exposure </li></ul><ul><li>IP Exposure </li></ul><ul><li>Legal Security </li></ul><ul><li>Packet Sniffing </li></ul><ul><li>Firewalls </li></ul><ul><li>IPSec </li></ul><ul><li>Intrusion Detection Systems (IDS) </li></ul>
  92. 92. Management Implications <ul><li>High demand for Technical talent </li></ul><ul><ul><li>Project Management </li></ul></ul><ul><ul><li>Business Knowledge </li></ul></ul><ul><ul><li>Communication Skills </li></ul></ul><ul><ul><li>High Salaries </li></ul></ul><ul><li>Retaining Talent </li></ul><ul><ul><li>Constructive & Timely Feedback </li></ul></ul><ul><ul><li>Recognition & Appreciation </li></ul></ul><ul><ul><li>Championing Staff Causes </li></ul></ul><ul><ul><li>Support Employee Career goals </li></ul></ul><ul><ul><li>Match Industry Standards for Salary </li></ul></ul>
  93. 93. Chapter Summary <ul><li>A network is a connection between at least two computers for the purpose of sharing resources. </li></ul><ul><li>Internet host numbers are divided into two parts: the network part (first two numbers) and the local part (second two numbers). </li></ul><ul><li>Messages, invoicing, and other information transmission on the Internet are made possible by protocols, standards, and other software that transmits information via packets through a cable to its destination. </li></ul><ul><li>The OSI Reference Model is a seven-layer model that defines the basic network functions. </li></ul><ul><li>The standard for the transport layer is TCP, which is the most popular standard used on the Internet. </li></ul>
  94. 94. Chapter Summary ( cont'd ) <ul><li>To communicate over a line, you need a modem, which converts incoming analog signals into digital signals. </li></ul><ul><li>Several factors need to be considered in designing a network: location, capacity, distance limitations, cost, potential growth, and security. </li></ul><ul><li>Factors to be considered in selecting network architecture include: hardware requirements, software requirements, disaster recovery and fault-tolerance requirements, and corporate culture and organizational factors. </li></ul><ul><li>The main implication of networking for management is that firms need to have a work environment that technical people find conducive for long-term employment and one that promotes a career path for qualified employees. </li></ul>