INternet,www & web

ASSESSMENT 
1. The ________________ is a collection of two or more computers.
a) Group
b) Computer network
c) joining
d) All the above

2. The central cable is the backbone of this network and is known as_____________.
a) Bus
b) Switch
c) Router
d) None of the above

3. A tree topology connects multiple star networks to other______________.
a) Star networks
b) Bus topology
c) Ring topology
d) Mesh topology
4. Wide Area Network (WAN) spans over a ______________ such as a state or a country.
a) Small geographical area
b) Large geographical area
c) Medium area network
d) As user wish

5. The word modem is derived from its function ___________.
a) Modulator/Demodulator
b) Modes/Diodes
c) Modulator/Di-modulator
d) All the above

Answers:
1. b
2. a
3. a
4. b
5.

Assessment 2 (True/False)
1. Transmission media not interconnect the computers in a network.
a) True b) False

2. Each computer on a Local Area Network (LAN) is called a node.
b) True a) False

3. Modem also re-converts the analog signals into digital signals.
a) True b) False
Answers:
1. b
2. b
3. a

Chapter-1 Introduction to Computer

Chapter-2 Introduction to Operating System Windows 10

Chapter-3 WORD PROCESSING USING MS –Word 2013

Chapter-4 SPREAD SHEET USING MS-EXCEL 2013

Chapter-5  Presentations 5 USING POWERPOINT 2013

Chapter-6 INTRODUCTION TO INTERNET, WWW AND WEB

Chapter-7 E-mail, Social Networking and eGovernance Services

Chapter-8 DIGITAL FINANCIAL TOOLS AND APPLICATIONS

Chapter-9 Overview on futuristic IT technology & Cyber Security






Topic: – What is Computer Networks?

 Definition

  • The Computer network is a collection of two or more computers, which are connected together to the share information and resources like (printers, scanners & other peripherals).
  • Network can be small or large, but permanently connected through wires or cables, or temporarily connected through phone lines or wireless transmission.
  • The main goal of computer network is to allow its users to access and share the resources of a network such as hard disk, the expensive laser printers, modems, licensed software, very powerful processors, etc. irrespective of their physical location.
  • The largest network is internet; it is a worldwide group of network.

 Topic :  Components of Computer Network

 Components of Computer Network

  • There are many components of the network, which share common devices, functions & features including
  • Servers
  • Clients
  • Transmission Media,
  • Network Adaptor,
  • Resources,
  • User,

Server

 A server provide services to other computers, which holds stored files, programs and network operating system.

  • Client

 The client computer access network & shared resources provided by the server.

 It is less powerful than server computer.

  • Transmission Media

Transmission media interconnect the computers in a network. Different types of transmission media are,

  • Wired or Bounded
    • Twisted-pair wire.
    • Coaxial cable.
    • Optical fiber cable.



  • Wireless or Unbounded
    • Wi-Fi.
    • bluetooth
    • Transmitter, Receiver

Network Adaptor

  • Network adaptor or Network Interface Card (NIC) is special expansion card, used for sending and receiving data & controlling the data flow between the pc

              Resources 

  • The term resource refers that specifically to data or routines that are available to programs.
  • eg. Printers, scanners, data, fax device and other network devices are the resources that are available to the client on the network.

                User or client 

  • Clients are computers to access the shared resources, which are connected to a particular network.
  • Protocols
  • Set of rules used for communication. These are the languages that computers.use to communicate with each other on a network.
  • Coaxial cable Twisted Pair wire Optical Fiber Cable
  • Otherwise it is a method of exchanging data over a computer network such as local area network, Internet, Intranet, etc

Topic : Importance of Computer

 Networks Importance of Computer Networks

  • User can share a single high-speed internet connection.
    • User can access the server centered database for better communication using internet services such as email, mailing list and Internet Relay Chat (IRC).
    • Sharing of devices such as printers and scanners.
    • Sharing of programs/software.
    • Sharing of files (Text, Audio, Video, Images, etc.).
    • It is used to store the information and retrieve it from a central location on the network



Types of Computer Networks

Computer Network is classified according to its

  • Geographic scale.
  • Connection method.
  • Functional relationship (Network Architecture).
  • Network topology.

Classification based upon their scale, network can be classified as

  • Local Area Network (LAN).
  • Metropolitan Area Network (MAN).
  • Wide Area Network (WAN).

Computer network is classified according to the connection method of hardware and software technology used to interconnect the devices in the network, such as

  • Optical fiber.
  • Ethernet
  • Wireless Local Area Network.

According to functional relationship, it is classified into,

  • Active Networking.
  • Client server.
  • Peer-to-Peer.

Based upon network topology it is classified into,

  • Bus Network.
  • Ring Network.
  • Star Network.
  • Hierarchical Network.
  • Mesh Network.

Local Area Network (LAN)

  • The LAN network consists of fewer or more computers which are directly connected within the geographical area such as
  • A home,
  • An office,
  • A single building.
  • Several buildings, such as on a huge college campus.
  • The devices used in this network can be connected via wired cable or wireless links.



  1. Each computer on a Local Area Network (LAN) is called a node.
  2. LANs are configured in any one of two basic structures.

Such as Peer-to-Peer.

Client/Server.

  1. Peer-to-Peer LAN consists of a small number of personal computers linked together.
  • A peer-to-peer (P2P) is created when two or more PCs are connected and share resources without the connection of serve system.
  • Each computer acts as both the server and clients, according to the situation.




Topic : LAN Topologies

LAN Topologies

  • Components in a LAN can be connected by several ways, as listed below
  • Star topology
  • Ring topology
  • Bus topology
  • Tree topology

 

Star topology

  • Star topology is one of the most common computer network topologies.

It is the easiest topology to design and implement

  • In this network all nodes are connected by cable (or wirelessly) to a central  node, is called hub or switch with point to point connection



  • A hub sends data packets (frames) to all the devices, and acts as a signal repeater. 
  • While using hub, transmission of a frame from one station to the node is repeated on all of outgoing links.
  • If central node is a switch, then incoming data packets processed at the node and retransmitted on the outgoing link.
  • Star Network may have problem of central node failure and also needs long cable length.

Advantage

  • Easy for install and wire.
  • Easy to detect faults and to remove parts.

Disadvantage

  • Requires more cable length.
  • If the hub fails,
  • nodes attached are disabled.

Ring topology 

  • Nodes in ring topology are connected in the form of closed loop.
  • Each packet is sent around the ring until it reaches its destination.
  • A ring can be unidirectional or multidirectional. In unidirectional ring, data moves in one direction. In a bidirectional ring, data moves in both directions.
  • Advantage
  • The advantage of using a ring network is short cable length, which suits for optical fiber implementation and It is very flexible to include new nodes.
  • Disadvantage

Drawbacks in this network are, if there is a failure of single node, it willv lead to failure of the entire network and it is also difficult to diagnose it




  • Bus topology
  • In bus topology, single cable that connects all the workstations, servers, printers and other devices on the network.
  • The central cable is the backbone of this network and is known as bus.
  • Advantage
  • Advantage is, even when there is a failure of one node, the rest of allv nodes will communicate with each other.
  • We can easily expand its structure by adding new nodes anywhere along the bus and also very less cost.
  • Disadvantage
  • Limitation over here is, the length of the bus and the number of nodes are limited and it is not suited for the network with heavy traffic.
  •  




  • Tree topology
  • A tree topology connects multiple star networks to other star networks.
  • It is integrated with bus and ring topology. In this topology, number of star network connected using bus.
  • The main cable looks like a tree which connects the other star networks as the branches. It is also called Extended Star Topology.

 Advantage

 Expansion of network is possible and easy.v  Point -to-point writing for individual segments.

Disadvantage

The maintenance becomes difficult, due to addition of more and morev nodes.  More difficult to configure and wire than other topologies.

Metropolitan Area Network (MAN)

  • Metropolitan Area Network is a network which is larger than a LAN but smaller than WAN.
  • It connects two or more LANs together, which are geographically separated but does not extend beyond the boundaries of a city/ town.
  • Routers, switches and hubs are used to create a Metropolitan Area Network.
  • A MAN is typically by a single entity such as a government body or large corporation.

Wide Area Network (WAN)

  • Wide Area Network (WAN) spans over a large geographical area such as a state or a country.
  • A Wide Area Network is different from MAN because of the distance between each of the network.
  • The world’s most popular and longest Wide Area Network is an Internet.
  • It makes communication of computers and users in one location with the computers and users in another location.
  • It covers long distance via telephone lines, fiber optic cables or satellite links.
  • The protocol used in a WAN is TCP/IP (Transmission Control Protocol/Internet Protocol) in combination of the devices such as router, switches, firewall and modems.



WAN Connection Types

  • The three different WAN connections that can be used to connect the LAN’s together are,
  • Dedicated connection.
  • Circuit switching.
  • Packet switching.
  • Dedicated connection
  • This connection is also referred as point-to-point connection or leased connection.
  • It uses synchronous serial lines up to 45Mbps.
  • No setup is made before transmission, it constantly transfers the data.
  1. Circuit switching
  2. The term circuit switching is same like a phone call.
  3. No data can transfer before end to end connection is established.
  4. It is used for low-bandwidth data transfer.
  5. Examples of circuit-switched networks are

Dial-up.

ISDN (Integrated Service Digital Network).

Packet switching 

  • Packet switching method allows user to share bandwidth with other companies to save money.
  • The packet switching transfers packets across a carrier network.
  • Speed can range from 56Kbps to T3 (45Mbps).
  • Examples of packet switching are,
  • Frame Relay,
  • 25 Network,
  • Internet Protocol,

Ethernet.




Comparison between LAN, MAN and WAN

LOCAL AREA NETWORK (LAN) METROPOLITAN AREA NETWORK (MAN) WIDE AREA NETWORK (WAN) All devices in LAN connection are within a building All devices in MAN connection are across buildings or small town All devices in WAN connection have no geographical boundaries. Very high speed Lower speed when compared to the LAN Speed varies on location of services. Switches and hubs are used to create a LAN connection Routers, switches and hubs are used to create a MAN connection It covers distance via telephone lines, fiber optic cable or satellite links.

World Wide Web (WWW)

  • WWW is a collection of internet sites that can be accessed using hypertext.
  • Hypertext is text that contains links, while clicking that link user may be directed to the related page. It may contain pictures, sound, video, animations etc. • WWW document can be created by using HTML language (Hyper Text Markup Language).

 Links between documents can be done by hyperlink.

  • HTTP (Hyper Text Transfer Protocol) is used to transfer a document.
  • The home page is starting/index page of all the web pages, which can be assigned as the default.
  • If a system with a web browser is installed, then it is called client system.
  • The host computer which is capable of providing information to other systems is called a server, it requires special software to provide the requested web document to others.

Basics of Internet Architecture

  • The Internet system consists of a number of interconnected packet networks supporting communication among host computers using the internet protocols these protocols include :
  • The Internet Protocol (IP).
  • The Internet Control Message Protocol (ICMP).
  • The Internet Group Management Protocol (IGMP).
  • Number of transport and application protocols.
  • All internet protocols use IP as the basic data transport mechanism.
  • IP is a datagram or connectionless, internetwork service and includes provision for addressing, type-of-service specification, fragmentation and reassembly, and security.
  • ICMP and IGMP are considered integral parts of IP although they are architecturally layered upon IP.
  • ICMP provides error reporting, flow control, first-hop router redirection and other maintenance and control functions.
  • IGMP provides the mechanisms by which hosts and routers can join and leave IP multicast groups.
  • Reliable data delivery is provided in the internet protocol suite by transport Layer protocols such as the transmission control protocol (TCP), which provides endto-end retransmission, resequencing and connection control.
  • Transport Layer connectionless service is provided by the User Datagram Protocol (UDP).
  • IP address: Pattern of 32 or 128 bits often represented in dotted decimal notation. E.g. 140.203.8.22 represents an Internet address.Ø 10001100 11001011 00001000 00010110.
  • The Internet technical architecture looks a bit like multi-dimensional river system, with small tributaries feeding medium-sized streams feeding large rivers.



World Wide Web

  • World Wide Web (WWW) is commonly known as Web.
  • The World Wide Web is a system of interlinked hypertext documents accessed via the internet.
  • Tim Berners-Lee invented the World Wide Web in 1989 which is today known as Internet.
  • There are three fundamental technologies of the web. They are,
  • HTML (Hyper Text Markup Language).
  • HTTP (Hyper Text Transfer Protocol).
  • URI (Uniform Resource Identifier).
  • The documents are formatted in a markup language called HTML (Hyper Text Markup Language) that support links to other documents as well as graphics, audio and video files.

Website

  • A website is a set of related web pages served from a single web domain accessible via a network such as the Internet or Local Area Network (LAN) through an internet address known as Uniform Resource Locator (URL).
  • A Website is a collection of World Wide Web (WWW) files that includes a startup file called a Home Page.
  • Websites can be classified into two types.
  • Static website.
  • Dynamic website.
  • Static Website
  • Static web page contain fixed code, the content of each page does not change unless it is manually updated by the webmaster.
  • A static website is primarily coded in Hyper Text Markup Language (HTML).
  • Appearance beyond basic HTML website is controlled using Cascading Style Sheets (CSS) language.
  • Images are commonly used for the effective appearance and also for the main content.

If audio or video plays automatically, then it is considered as Static content.



  • Advantages of static website
  • Quick developing time.
  • Cheep development cost.
  • Host is inexpensive / affordable.
  • Disadvantages of static website
  • Web development skills are required in order to update the site.
  • Not as useful to the user.
  • Content can become outdated.
  • Dynamic Website
  • A Dynamic website is one in which the web pages changes or customizes itself frequently and automatically.
  • Server-side dynamic pages are generated by computer code that produces the HTML and CSS.
  • There is a wide range of scripting languages and web servers that are available to generate dynamic web servers and scripting languages such as CGI, Java Servlets and Java Server Pages (JSP), Active Server Pages and Cold Fusion (CFML) are some of the examples.
  • A dynamic website can display the current state of the communication between users, monitor a changing situation, or provide information that is required by an individual user.

JavaScript code is used to instruct the web browser how to interactively modify the page contents at client side



  • Advantages of dynamic website
  • A highly functional website.
  • Very easy to update.
  • More than one user can develop/work on the site.
  • Disadvantages of dynamic website
  • Takes longer time to develop.
  • More costly to develop.Cost more to host.

Communication on Internet

  • Basically, communication is the process of transmitting information from one place to another.
  • As most of us know, internet was developed for the United States army as a source of communication but it soon became public – ARPANET (Advance Research Projects Agency Network) established in 1969.
  • There are wide varieties of different methods of communication and information exchange over the network.
  • Internet refers to a network of networks that consists of millions of private, public, academic, business, government networks, of local to global scope, that are linked by a broad array of electronic and optical networking technologies.
  • Internet communication at the beginning, started through the use of email.
  • A multi-tiered system of local, regional, and national ISPs has evolved to provide access to the Internet, transport data and to provide value-added Internet services and enhancing the internet communication

The common methods of communications over the Internet can be roughly grouped into six categories.

  • One-to-one messaging
  • One-to-many messaging.
  • Distributed messaging databases.
  • Real time communication.
  • Real time remote computer utilization.
  • Remote information retrieval.
  • One-to-one messaging

The simplest method of communication in the Internet is via electronic mail, or e-mail. 

An individual can transmit a message to one or more specific other individuals. FIG 5.32: One-to-one messaging

One-to-many messaging

  • The Internet contains automatic mailing list services that allow simple and efficient communications about particular subjects of interest.
  • An individual can subscribe to a listserv mailing list on a particular topic and  can submit messages to the listserv that are automatically forwarded to anyone who has subscribed to the mailing list.

Distributed messaging databases

  • Distributed message databases such as USENET newsgroups are used for communication.
  • Like listserv, newsgroups are open discussions and exchange messages on particular topics.
  • There are newsgroups on more than fifteen thousand different subjects.
  • The messages are temporarily stored on each receiving computer where they are available for review and response.
  • The messages are automatically purged from each system to make room for new messages.
  • Real time communication
  • An individual can engage to immediate dialog/chat in real time with other individuals on the Internet.
  • Simply it is a one-to-one communication and Internet Relay Chat allows two or more individuals to type messages to each other that almost immediately appear on the other individual’s computer screens.
  • Real time remote computer utilization
  • Another method to utilize information on the Internet is to access and control remote computers using
  • An individual can link via Telnet to a computer to interact directly and communicate with other users linked to the same computer.
  • Remote information retrieval
  • The final major category of communication is the most important.
  • The search for and retrieval of information located on remote computers

 Modem

  • A modem is a device that converts digital computer signals into a form (analog signals) that can travel over phone lines.
  • The word modem is derived from its function Modulator/Demodulator.
  • Modem also re-converts the analog signals into digital signals.
  • Modem has two types of connectivity. They are Wired and Wireless connectivity.
  • Wired connectivity: Dial-up, DSL (Digital Subscriber Line) & ADSL (Asymmetric Digital Subscriber Line), Cable internet access.
  • Wireless connectivity: 3G, WIMAX, Wi-Fi, Wireless MAN

ISPs and examples (Broadband/Dialup/Wi-Fi)

ISPs (Internet Service Provider)

  • ISPs is an organization that provide services for using, accessing, participating in the internet. ISPs may be organized in various forms, such as profitable, nonprofit, commercial, private owned.
  • First ISPs were established in Australia and United States in 1989.
  • ISPs provide some Internet Services such as Internet access, Internet transit, domain name registration, web hosting, collocation (connection).
  • Different types of Internet Services Provider are as follows.
  • Access ISPs,
  • Mailbox ISPs,
  • Hosting ISPs,
  • Transit ISPs,
  • Virtual ISPs,
  • Free ISPs,
  • Wireless ISPs.
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