1. Benefit of networks Topics to be discussed Reasons for Networking.
Review of Remote access.
LAN, WAN & MAN.
Network Application.
Cost/Benefit analysis of network use.
Network resources.
Network operating system.
Network security.

2. Reasons For Networking.
Cost reduction by sharing hardware & software resources.
High reliability by having multiple sources of supply.
Cost reduction by downsizing to microcomputer based networks instead of using mainframes.
Greater flexibility because of possibility to connect devices from various vendors.
Increase productivity by making it easier to share data amongst users

3. Advantages of Computer Networks
Price/Performance Ratio
Performance Quality
Reliability
Accessible Resources
Incremental Growth of Computing Power  

4. Disadvantages of Computer Networks
Disk space management
Resource management
Network Architecture management

5. Characteristics Of Different Systems
Stand Alone System
Network Systems
Distributed System

6. Stand Alone System Description : One Computer.
Advantage : Isolation – Security is simple.
Disadvantage : Limited resources; no communication.

7. Network Systems Description : Stand alone Computer plus communication.
Advantage : Resource sharing, message passing.
Disadvantage : Security risks; complexity in programs using remote resources.

8. Distributed System Description : Network plus transparency.
Advantage : Redundant resources; adapt to system load ; compensate for down systems.
Disadvantage : Additional overhead to keep replicated files consistent, to search for needed resources, to protect against conflicts in access.

9. Evolution Of Networks
Centralized,
Distributed, and
Collaborative.

10. Centralized Computing
Advantages:
Ease of back up.
Security.
Low cost.
Disadvantages:
Slow network access.
Fewer options.

11. Distributed Computing
Advantages:
Quick access.
Multiple uses.
Disadvantages:
Virus susceptibility.
Backup difficulty.
File synchronization.

12. Collaborative Computing
Advantages:
Extremely fast.
Multiple uses.
Disadvantages:
Susceptible to viruses.
Difficult to back up.
Difficult file synchronization.

13. Clients & Servers
Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power.
Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers ).

14. Client/ Server Architecture
A network architecture in which each computer or process on the network is either a client or a server. Client-server architectures are sometimes called two-tier architectures.

15. Working of Client/ Server Network

16. Advantages Client/Server Networks
Centralized security.
Dedicated servers.
Easy accessibility.
Easy backup.
Synchronized files.

17. Disadvantages of Client/Server Networks
Dependent on an administrator.
Expensive server.

18. Peer-to-Peer Network architecture
A communications network that allows all workstations and computers in the network to act as servers to all other users on the network. Dedicated file servers may be used, but are not required as in a client/server network.Here Data and resources are distributed throughout the network, and user is responsible for sharing data and resources connected to their systems.

19. Advantages of Peer to Peer Networks
Inexpensive
Easy setup
Easy maintenance

20. Disadvantages of Peer to Peer Networks
No central administration
Scattered data
Evasive resources
Weak security
Dependent on user training.

21. Review of Remote access
Intranet
Internet

22.
It is an electronic message sent from one computer to another. You can send or receive personal and business-related messages with attachments, such as pictures or formatted documents. You can even send computer programs.

23. How it works When you send an e-mail message
Your computer sends it to an SMTP server.
The server forwards it to the recipients mail server depending on the address.
The received message is stored at the destination mail server until the addressee retrieves it

24. Understanding E-mail addresses
Typical address
User name.type of domain
User name – refers to recipients mailbox.
Domain name – refers to mail server ie. The computer where the recipient has an electronic mail box.
Type of domain – whether the host is a government, commercial, educational etc organization.
Ex :

25. Sending an E-mail message
Open your program and launch a new message window by clicking on the appropriate icon

26. Sending an E-mail message
In the TO box, type in the name of the recipient. It should take this form:
You can send a message to more than one person by entering multiple addresses. Just put a semi-colon (;) between each address.

27. Sending an E-mail message
Type in the subject of the .

28. Sending an E-mail message
Write your message in the message window. You can also copy text from a word processing program and paste it into the window.

29. Sending an E-mail message
Click on the Send icon or select Send from the File menu.

30. Difference between E-mail & WWW Address

31. Intranet
A network based on TCP/IP protocols belonging to an organization, usually a corporation, accessible only by the organization's members, employees, or others with authorization.

32. Technology Components of Intranet
Communication Protocol.
File Transfer.
Mail.
Web Browsing.

33. Potential Functionality of Intranet
Information sharing/distribution
Intra-company communications
Decentralized processing for certain functions
Hosting Web based applications
Intelligent routing with tracking and electronic signatures (workflow automation management)

34. Advantages of the Intranet
Easy to use.
Information Sharing.
Inter-department communication.
Saves Stationary Through rapid online distribution of information.
Saves the time spent for hunting up information.
Based on open standards
Scaleable and flexible
Connects across disparate platforms

35. Internet What is Internet. Birth of the net. How Web works.
Making Connections.
Web Browsers.
Domain names.
Search Engines.
Understanding Web addresses.

36. Internet Global network connecting millions of computers.
"The" Internet is made up of well over 100,000 interconnected networks in more than 100 countries covering commercial, academic and government endeavors.

37. Birth of the net.
The Internet began as the ARPANET during the cold war in It was developed by the US Department of Defense (DOD)

38. How Web works Enter the address of the web site in your web browser.
Browser requests the web page from the web server.
Sever sends data over the Internet to your computer.
Your web browser interprets the data & displays it on your computer screen.

39. Connecting to the Internet
Dail up Connection – Suitable for small networks & connection is made using a modem .
ISDN Connection – used when higher speed is needed & you need a dial-up ISDN account .
Dedicated high bandwidth connection –Used when Internet connection needs to be available any time .

40. Web Browsers.
A software application used to locate and display Web pages.
The two most popular browsers are Netscape Navigator and Microsoft Internet Explorer.
Both of these are graphical browsers, which means that they can display graphics as well as text.

41. Domain names.
Domain names are used in URLs to identify particular Web pages. For example, in the URL the domain name is hotmail.
Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses.

42. Domain names(contd..)
Every domain name has a suffix that indicates which top-level (TLD) domain it belongs to. There are only a limited number of such domains. For example:
gov - Government agencies
edu - Educational institutions
org - Organizations (nonprofit)
mil - Military
com - commercial business
net - Network organizations
ca - Canada
th - Thailand
Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain
Name System (DNS) server to translate domain names into IP addresses.

43. Search Engines
A program that searches documents for specified keywords and returns a list of the documents where the keywords were found.
Some of the search engines are AltaVista, Lycos, Yahoo, Excite etc.

44. Understanding Web addresses
URL - Abbreviation of Uniform Resource Locator, the global address of documents and other resources on the World Wide Web.

45. Understanding Web addresses
For example, the two URLs below point to two different files at the domain ignou.edu.
The first specifies an executable file that should be fetched using the FTP protocol;
the second specifies a Web page that should be fetched using the HTTP protocol:
ftp://

46. Difference Between Internet & Intranet
So what is the difference between the Internet and Intranet? Mainly the location of the information and who has access to it.
Internet is public, global and wide open to anyone who has an Internet connection.
Intranets are restricted to people who are connected to the private company network. Other than that, they work essentially the same way.

47. Difference Between Internet & Intranet
Public
Private
World wide
Within the Company

48. Similarity Between Internet & Intranet
Both run on Network.
Both use the same type of software (eg.Netscape).
Both carry Documents, Data & Multimedia.
Intranet = Same technology used in Internet but everything is in-house.

49. LAN, MAN,& WAN
Based on geographical areas covered as Networks can be divided into :
LAN,
MAN,&
WAN

50. LAN : Local Area Networks
Developed in 1970s.
Typically connects computer in a single building or campus.
Medium : optical fibers, coaxial cables, twisted pair, wireless.
Speeds adequate for most distributed systems
High speed networks (0.2 to 100 Mb/sec).

51. MAN : Metropolitan Area Networks
Developed in 1980s.
Generally covers towns and cities (50 kms)
Medium : optical fibers, cables.
Data rates adequate for distributed computing applications.

52. WAN : Wide Area Networks
Developed in 1960s.
Generally covers large distances (states, countries, continents).
Medium : communication circuits connected by routers. .
Problems with delays if using satellites.
Typical speed : Kbits/s.
Not (yet) suitable for distributed computing.

53. Networked Application
Sharing Resources.
Accessing Resources.

54. Cost / Benefit Analysis Of Network Use
Resource Sharing
High Reliability
Saving Money
Scalability
Communication medium
Increased Productivity

55. Resource Sharing
The main goal is to make all programs, equipment, and data available to anyone on the network without regard to the physical location of the resource and the user.

56. High Reliability
Goal of computer networks is to provide high reliability by having alternative sources of supply.

57. Saving Money
Small computers have a much better price/performance ratio than larger ones . This imbalance has caused many systems designers to build systems consisting of personal computers, one per user, with data kept on one or more shared file server machines

58. Scalability
The ability to increase the system performance gradually as the workload grows just by adding more processors.

59. Communication medium
A computer network can provide a powerful communication medium among widely separated users.

60. Increased Productivity
Networks increase productivity as several people can enter data at the same time, but they can also evaluate and process the shared data