MCSL-016 INTERNET CONCEPTS AND WEB DESIGN, (SCRIPTING LANGUAGE), MCSL 016 INTERNET CONCEPTS AND WEB DESIGNING - SCRIPTING LANGUAGES; INDIRA GANDHI NATIONAL OPEN UNIVERSITY, IGNOU, FIRST SYMESTER, FIRST YEAR, (THE INTERNET, INTRODUCTION TO HTML, ADVANCE HTML, JAVA SCRIPT, VBSCRIPT, DREAMWEAVER);

MCSL-016 INTERNET CONCEPTS AND WEB DESIGN, IGNOU 2011 SYLLABUS;

(SCRIPTING LANGUAGE), MCSL 016 INTERNET CONCEPTS AND WEB DESIGNING - SCRIPTING LANGUAGES; INDIRA GANDHI NATIONAL OPEN UNIVERSITY, IGNOU, FIRST SYMESTER, FIRST YEAR, (THE INTERNET, INTRODUCTION TO HTML, ADVANCE HTML, JAVA SCRIPT, VBSCRIPT, DREAMWEAVER);
NOTE: These are my/our personal notes, for personal use, please follow your own books and syllabus, i/we are not responsible for any error/errors in these notes, thanks.
======================================================

COURSE INTRODUCTION : Internet is a hot topic today.  It has revolutionized the way we live,work, learn and communicate with each other. It has opened up new gateways of opportunities for education and helped increase productivity, as well efficiency in areas like healthcare banking, governance, and manufacturing all over the world.

As IT Professionals we have to deal with the whole range of Web Technologies starting from the Internet, i.e. to HTML, Advanced HTML, Java Script, VB Script, XML, COM, JSP, ASP, Dream Weaver, etc.  The purpose of the course is to introduce some of these technologies.  In the first Block of course, We study how to design specific page and dynamic web pages. We will also examine forma and frames, two of the most important features of the web pages. The second part of the course, We focus on the practical issues. Each topic is covered in the 10 practical sessions of three hours duration each.

======================================================

BLOCK INTRODUCTION

This block (MCSL016 - I.C.W.D. - SCRIPTING LANGUAGE) introduces three major topics namely, Internet, Scripting Languages, and HTML Editor. Internet has been discussed in the first unit and remaining four units focuses on Scripting Language and the last unit is about Dreamweaver, which is a HTML Editor. The block is organized as follows :
===============================================
Unit 1 : In this unit, lessons describe about the classification of Different Computer Network and then describes how does the Internet work? Unit/ Book also take up practical issues like : how to configure a browser, how to connect to Internet etc. Internet is based on two standard protocols TCP & IP, (OR WE CAN SAY INTERNET PROTOCOL SUIT) (OR DIFFERENT TYPE OF INTERNET PROTOCOLS) which has also been discussed in brief. At the end of this unit we describe different types of services provided by the Internet.
Unit 2 : This unit is about HTML, which is a Scripting Language. When we connect to a Web Site, the Web Server on on the remote computer presents our browser with a file in a special format. The contennts of the file are stored in a special format-usint HTML. The unit introduces a large number of tags.
Unit 3: Describes how to make interactive Web sites for which we require features like, frames, tables, and forms accepting user input.
Unit 4: In this unit we are going to learn about another Scripting Language, Java Script code and insert name into HTML documents and how to make the Web Page more dynamic and interactive.
Unit 5: This unit is about VBScript, a Microsoft Scripting Language. This is the last unit on Scripting Language, which is quite common. VB Script is a Microsoft Scripting Language. It enable us to write programs that enhance the power of Web Page by allwing to control their behaviour. It also discusses about objects in VBScript and talk about dictionary object as an example.
Unit 6: The last unit of this block is about HTML Editor, which is a tool for managing and creating a Web Site. At the end of this unit we discuss how to choose option, use inspectors and panels, and set preferences that best fit our work styles.

Reference : 1. The Internet By Douglas E. Comer.
2. Web Technologies by Achyut S Godbole and Atul Khate.
3. Data Communication & Networking by Bchrouz A. Forouzan.
4. Computer Networking by James F. Kurose, Keith, W. Ross, Pearson.
5. Computer Networking by A.S. Janenbaun, 4th Edition, PHI.
======================================================
UNIT-1 : THE INTERNET

======================================================
1.0 - Introduction

1.1 - Objectives

1.2 - Classification of Networks

1.3 - Networking Models

1.4 - What is Packet Switching ?

1.5 - Accessing the Internet

1.6 - Internet Protocols
----- 1.6.1 - Internet Protocol - IP

----- 1.6.2 - Transmission Control Protocol (TCP)

1.7 - Internet Address 

----- 1.7.1 - Structure of Internet Servers Address

----- 1.7.2 - Address Space

1.8 - How does the Internet Work ?

1.9 - Internet & Extranet 

1.10- Internet Infrastructure
1.11- Protocols and Services on Internet

----- 1.11.1 - Domain Name System

----- 1.11.2 - SMTP and Electronic Mail

----- 1.11.3 - HTTP and (WWW) World Wide Web

----- 1.11.4 - Usenet and News-groups

----- 1.11.5 - FTP

----- 1.11.6 - Telnet

1.12- Internet Tools

----- 1.12.1 - Search Engines

----- 1.12.2 - Web Browsers

1.13- Summary

1.14- Solutions / Answers

======================================================
1.0 INTRODUCTION

The Internet is worldwide computer network that interconnects, million of computing devices throughout the world. Most of these devices are PC's and servers that store and transmit information sucha as web pages and e-mail messages. Internet is revolutionizing the enhancing the way we as humans communicate, both locally and around the globe. Everyone wants to be a part of it because the Internet literally puts a world of information and a potential world-wide audience at your fingertips.

The Internet evolved from the ARPANET (Advanced Research Projects Agency) to which other networks where added to form an inter network, The present Internet is a collection of several hundred thousand of networks rather than a single network. From there evolved a high-speed backbone of Internet acces for sharing these of networks. The end of the decade saaw the emergance of the World Wide Web, which heralded a platform -independent means of communication enhanced with a pleasant and relatively easy-to-use Graphical Interface (GUI).

 

CLICK THE IMAGE TO ENLARGE --------------------

                                             ||
                                             \/

World Wide Web (or WWW) - is an example of an Information Protocol/ Service that can be used to send and receive information over the Internet. It supports:

• Multimedia Information (text, movies, pictures, sound, programs... ).
• Hyper Text Information (information that contains links to other information resources).
• Graphic User Interface or GRAPHICAL USERE INTERFACE - GUI - (so users can point and click to request information instead of typing in text commands) like Mouse, Pointing Devices, Touch Pad, Video Inputs etc.

The World Wide Web model follows Client/ Server software design. A service that uses client/ server design requires two pieces of software to work: Client Software, which you use to request information, and Server Software, which is an Information Provider.

The server software for the World Wide Web is called an HTTP Server(or informally a web server). Examples are Mac HTTP, CERN HTTP (CERN IS European Organization for Nuclear Research), and NCSA HTTP   (NCSA = National Center for Supercomputing Applications), The client softwares for World Wide Web is called a Web Browsers (examples are : Internet Explorer, Mozilla Firefox, Netscape Nevigator, Opera, Chrome, etc.)

(NOTE: CERN FULL FORM - Conseil Européen pour la Recherche Nucléaire )
= = = = = = = = = = = = = = = = = = = = = = = = = =  = = = = = = = = = = = =
1.1 OBJECTIVES :
After going through this unit students / we - should be able to :

• Make classification of Networks (variour Network Topologies);
• Understand Two types of Networking Models OAI MODELS;
• Understand the concept of Packet Switching;
• Understand how to access to the Internet;
• List the services available on Internet; and to
• Understand how does the Internet or Intranet Works.

1.2 CLASSIFICATION OF NETWORKS :
There are different approaches to the classification of Computer Networks. One such classification is based on the distance approach. In this section we will discus such networks.
.

The networks can be classified into LAN, MAN and WAN networks. Here we desctibe them into brief to understand the different between the types of network.
.

Local Area Network (LAN) : LAN is a privatey - owned computer networks confined to small geographical area, such as an office or a factory Widely used to connect office PCs to share Information and Resourses (such as peripheral devices - printer, scanner, softwares, hardware etc..  In a Local Area Network - two or more computers are connected by same physical medium, such as a transmission cable. An important characteristic of Local Area netwoks is speed. i.e. they deliver the data very fast compared to other type of networks with ptypical data transmission speed are 10-100 Mbps (or in market we say 10/100 LAN Card).

A wide variety of LANs have been build and installed, but a few types have more rcently become dominant. The most widely used LAN system is the Ethernet System. Intermediate Nodes (i.e. repeaters, bridges, switches, routers, etc.) - allow LANs to be connected together to form large LANs. A LAN may also be connected to another LAN or to WANs and MANs using a "ROUTER".

SUMMARY OF LAN : ---

1. LAN is a Communication Network (Home, School, Offices etc.).
2. Useful in - One Building or Group of Buildings / Rooms etc.
3. Controlled by one Administrator Authority.
4. It is High Speed 10/100, and is always shared.
5. We can share mostly all resourses by LAN.
6. We can Control over other Desktop or Multiple Desktops through LAN.
7. LAN is usefur for Building - other / Multiple and Big Networks.
8. Networking is done by CAT Cables and RJ Connectors.

= = = = = = = = = = = = = = = = = = = =  = = = =  = = = = = = = = = =  = = = = =

Metropolitan Area Network or MAN :

A MAN, basically a bigger version of a LAN is designed to extend over an entire city. It may be single network such as a cable television network, or it may be a means of connecting a number of LANs into a large network so that resources may be shared for example, a company can use a MAN (Metropolitan Area Network) to connect the LANs in all of its office throughout a city.

A MAN typically covers an area of between 5 and 50 Km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of Buildings.

The MAN, its communications links and equipment are generally owned by either a consortium (संघ) of users or by a single network provider who sells the service to the users. This level of service provided to each user must therefore be negotiated with the MAN operator, and some performance guarantees are normally specified.

A MAN often acts as a high-speed network to allow sharing of regional resources (similar to a large LAN). It is also frequently used to provide a shared connectio to other networks using a link to a WAN.

SUMMARY OF MAN : ---

1. MAN - IS BIGGER VERSION OF - LAN; (OR MAN IS GROUP OF LAN)
2. LIKE CABLE TV, AND INTER CITY NETWORKS;
3. A COMPANY CAN JOIN ALL ITs OFFICE IN A CITY BY MAN;
4. FROM 5 - 50 KILO METER -- TO -- ENTIRE CITY (REPEATERS AND ROUTERS ARE USED).
5. MORE THEN ONE ADMINISTRATORS (NETWORK ADMINS.);
6. SAME AS LAN - WE CAN SHARE RESOURCES IN - MAN;
7. 34 - 155 Mbps.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Wide Area Network (WAN) :

The term Wide Area Network (WAN) usually refers to a network, which covers a large geographical area, and use communication subnets (circuits) to connect the intermediate nodes.  A major factor impacting WAN design and performace is a requirement that they lease communication subset from telephone companies or other communication carriers.  Transmission rates are typically 2 Mbps, 34, Mbps, 155 Mbps, 625 Mbps (or sometimes considerably more).  the basic purpose of th subnet is to transmit message from one end to another end through intermediate nodes.

In most WAN a subnet consists of two types of elements: (i)Transmission Lines; (ii)Switching Element.
Transmission Lines - also called channels move about from one machine to another machine. The basic purpose of the switching element is to select the outgoing path for forwarding the message.
Numerous WANs have been constructed, including public switched networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks. A WANis wholly owned and use ny a single comapny is oftern referred to as an enterprises network.
SUMMARY ABOUT WAN :

1. WAN Covers - Large Geographical Area.
2. They Lease communication subsets from Tel. Companies / Communication Carriers (Airtel, MTNL, BSNL, VSNL, Bharti Telecommunications etc.)
3. Transmission Rate is - 2 Mbps, 34, Mbps, 155 Mbps, 625 Mbps or more (sometime 1 Gbps).
4. WAN subnet consist of two types of Elements (1) Transmission Lines (2) Switching Elemennt.
5. Transmission Lines are Channels from one Machine to another, WHILE - Switching Elements are path to Forwarding Messages.
6. WAN used mostly in Large Companies, Military, Banking, Stock, Airline, Train, Govt. Offices.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
1.3 NETWORKING MODELS (OSI & TCP/IP) - There are two types of Networking Models available: (1)OSI and (2) TCP/IP;
OSI (Open System Interconnection) Networking Model : An Open system is a model that allow any two different systems to communicate regardless of their underlying architecture. The purpose of teh OSI model is to open communication between different devices without requiring change to the logic of the underlying hardware and software.
The OSI model is not a protocol, it is a model of understanding and designing a network architecture that is inter- operable (अंतर - प्रचलित), Flexible and Robust (मजबूत).  The OSI model has a seven - lsyered architecture. These 7 LAYERS ARE :

1. PHYSICAL LAYER - to send the Raw Bits between physical medium.
2. DATA LINK LAYER - to transmit a group of bits between the adjacant (समीपवर्ती, nearby, निकटस्थ, संलग्न) nodes.
3. NETWORK LAYER - responsible for routing a packet within the subnet that is, from source to destination nodes across multiple nodes in the same network or across multiple networks. (i.e. same subnet mask like 255.255.255.0 etc etc.)
4. TRANSPORT LAYER - this is end to end layer, header of the transport layer contains information that helps send the message to the corresponding layer at the distination node.
5. SESSION LAYER - responsible for establishing / maintaining and synchronizing the interaction between two communication hosts. 
6. PRESENTATION LAYER - Data encryption / decryption / Compression / Translation etc.
7. APPLICATION LAYER -  provides user interface for network applications such as remote login, WWW and FTP. responsible for file access / transfer, mail services, remote login, WWW.

NETWORK LAYERS IN DETAIL

:

1. PHYSICAL LAYER : Responsible for sending raw bits between the source and destination nodes over a physical medium. The source and destination nodes have to agree on a number of factors.
   - SIGNAL ENCODING : how are the bits 0 and 1 to be represented ?
   - MEDIUM : type of medium used and its properties ?
   - BIT SYNCHRONIZATION (तुल्यकालन, समकालीन बनाने की क्रिया, समकालीकरण) : is the transmission synchronous or asynchronous (अतुल्यकालिक) ?
   - TRANSMISSION TYPE :
   - TRANSMISSION MODE :
   - TOPOLOGY :
   -
   -
   
   The physical layer defines electrical and physical specifications for devices. In particular, it defines the relationship between a device and a transmission medium, such as a copper or optical cable. This includes the layout of pins, voltages, cable specifications, hubs, repeaters, network adapters, host bus adapters (HBA used in storage area networks) and more.

OSI Model
	Data unit	Layer	Function
Host layers	Data	7. Application	Network process to application
		6. Presentation	Data representation, encryption and decryption, convert machine dependent data to machine independent data
		5. Session	Interhost communication
	Segments	4. Transport	End-to-end connections, reliability and flow control
Media layers	Packet/Datagram	3. Network	Path determination and logical addressing
	Frame	2. Data Link	Physical addressing
	Bit	1. Physical	Media, signal and binary transmission