Internet - Services - Advantages and Disadvantages [Computer Science - Grade X - New Syllabus]

 Internet - Services - Advantages and Disadvantages [Computer Science - Grade X - New Syllabus]

Internet [SLC 2065 S] [SLC 2066] [SLC 2069] [SLC 2069 S] [SLC 2071 S] [SEE 2074] [MFT 2075]

Internet is an interconnection of several thousands of computers of different types belonging to the various networks all over the world in order to share data and information.

 In other words network of networks is called Internet.

 

Who controls internet?

Different organization like ISOC (Internet Society), W3C (World Wide Web Consortium), IAB (Internet Architecture Board), IEFT (Internet Engineering Task Force), IRTF (Internet Research Task Force), IESG (Internet Engineering Steering Group) and INIC (Internet Network information Centre) gives directive and guideline for the proper use of internet.

 

Internet called Network of networks [PMT 2075K]

The internet is called ‘network of networks’ because all the smaller networks of organizations are linked together into the one giant network called the internet.

 

Protocol used by the internet.

TCP/IP is the communication protocol used by the internet.

 

Components required for internet connection

a)      A TCP/IP enabled computer with web browser

b)     An account with an ISP

c)      Router / MODEM (necessary if you are using a telephone line to access the Internet)

d)     Connection (ISDN, Satellite, cable and dial-up)

 

ADSL (Asymmetric Digital Subscriber Line) [SQE 2074K]

ADSL is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses. Unlike regular dialup phone service, ADSL provides continuously-available, "always on" connection.

 

Services of internet [SLC 2065] [SLC 2068] [SEE 2072] [MFT 2075] [U1]

a)      WWW (World Wide Web)

b)     E-mail (Electronic mail)

c)      FTP (File Transfer Protocol)

d)     IRC (internet Relay Chat)

e)      Newsgroup

f)      Telnet

g)     E-commerce

 

Advantages of internet [SLC 2065 S] [SEE 2075]

a)      Internet has an endless knowledge supply which anyone can access that too free of cost.

b)     Selling and buying has become so easy with the use of internet and it has helped millions to sell and buy their goods online.

c)      Internet has given us E-Mail which is fast, secure and reliable mode of communication.

d)     It makes easy to transfer the file or information.

 

Disadvantages of internet

a)      Increasing virus threats not only steals your sensitive data but also damages your computer.

b)     People using too much of internet get disconnected from the real world. 

c)      Pornography that can get in the hands of young children too easily.

d)     Addiction to online games affects health leading to obesity and serious health issues.

 

Intranet

An intranet is a private computer network that uses the internet protocol to securely share any part of information of an organization. It is owned by a single organization or company. It can only be used by the employees of the owned organization.

 

Extranet

An extranet is a computer network that allows controlled access from outside for specific business or educational purposes.

 

ISP (Internet Service Provider) 
An Internet service provider (ISP) is an organization that provides services for accessing and using the Internet. World Link, Mercantile, Classitech, Vianet etc are the ISPs of Nepal.

 

E-mail (Electronic Mail) [SLC 2068 S] [SLC 2069 S] [SEE 2075 S2] [MM 2076] [MFT 2075]
E-mail (Electronic mail) is one of the most popular services provided by the internet which exchanges messages between the computers through a network. It is the soft copy service of the internet.

E-mail can be sent using a computer with modem, e-mail program and internet facility.

E.g. xyz@gmail.com

Any four sites that provide e-mail services are:

a)      www.yahoomail.com

b)     www.hotmail.com

c)      www.gmail.com

d)     www.outlook.com

 

Advantages of E-mail [SEE 2067 S] [SLC 2070] [SEE 2073 U] [MM 2076] [MF 2076] [MFT 2075]

a)      It allows to send and receive message across the world at very low cost.

b)     E-mail is faster, cheaper, more reliable than traditional mail.

c)      The image, sound, video and documents can be attached to e-mail message.

d)     Email can be accessed from anywhere in the world.

 

Disadvantages of e-mail
i) Minor mistakes in e-mail address may deliver the mail to wrong address.
ii) Since it passes through a vast electronic network, it may be seized in between.

 

Newsgroup
Newsgroups are discussion groups that focus on a particular topic such as politics, health, computer, etc. The interested people on the particular field write the information or articles. Then these articles are posted to the newsgroup so that other people can read them.

 

Telnet
A telnet is a program that allows a user to log in to a remote computer on internet as a user on that system.

FTP (File Transfer Protocol) [MFT 2075]
File Transfer Protocol is the internet tool that allows the user to transfer the file from one computer to another computer. It helps to upload and download the files.

 

Use / Function of FTP [SLC 2071] [SEE 2073]

File Transfer protocol helps to transfer (download or upload) files from one computer to another computer.

 

Uploading [MF 2076] [MFT 2075]
Uploading refers to copying files or documents, programs or data from the user computer to the internet server.

Downloading [MF 2076] [MFT 2075]
Downloading refers to the copying files or document or program or data from the internet server to the user computer.

 

IRC (Internet Relay Chat) [MFT 2075]
Internet Relay Chat is one of the important services provided by the internet which allows the user to communicate with other people in real time.

It uses the browser software without using special chat software. It communicates only text.

For eg: chatting on facebook.

 

FAQ (Frequently Asked Questions)

FAQ (Frequently Asked Questions) is an online document that possesses series of common questions and answers on a specific topic.

 

Video conferencing
Video conferencing is an important and interesting service provided by the internet which makes communication using sounds as well as pictures. It requires necessary hardware and software to see and speak to each other.

It enables virtual face-to-face communication among people sitting at different locations.

For eg: chatting on skype.

 

Web browser [SEE 2075 U] [SLC 2067] [MF 2076]
Web browser is a computer program that access web pages and displays them on the user computer.

Examples of web browsers are Mozilla Firefox, Google chrome, Internet Explorer, opera etc. Browsing/ Surfing means searching information on the internet.

 

URL (Uniform Resource Locator)
Ans: URL is a unique address that provides location of a webpage on the internet.

Example of URL: http://www.abc.com/mainpage/first.html

http: protocol name, www.abc.com: server name, mainpage: path, first.html: filename

 

Search engine [SEE 2074 U] [SQE 2075K]
Ans: A search engine is a software program or script available through the Internet that searches documents and files for keywords and returns the results of any files containing those keywords. They are used to locate specific sites and information. Examples of search engines are Google, Bing, Yahoo etc

 

Blog (weblog)

A blog is a time-stamped online journal that appears on a website. A blog is a frequently updated online personal journal or diary. A place to share your thoughts and your passions to the world.

 

Wi-Fi (Wireless Fidelity)

Wi-Fi is the name of a popular wireless networking technology that uses radio waves to provide wireless high-speed Internet and network connections.

 

WWW (World Wide Web)

The World Wide Web (abbreviated WWW or the Web) is an information space where documents and other web resources are identified by Uniform Resource Locators (URLs), interlinked by hypertext links, and can be accessed via the Internet.

 

DNS (Domain Name System)

Domain Name System is an Internet service that translates domain names into IP addresses.

Network architecture (Models of Computer Network) - Client/Server, Peer to peer, centralized [Computer Science - Grade X - New Syllabus]

 

Network architecture (Models of Computer Network)

The arrangement of the computers on the network which is based on the computing model is called network architecture. Its types are

a)      Centralized computing network

b)     Client / Server Network

c)      Peer to Peer Network

 

Centralized computing network [SQE 2074K]

A centralized computing network is a network in which a central host computer performs data processing and storage on behalf of clients. It is different from client server network as client server network consists of at least one server and one or more client as well as client server provides high security of data and other resources.

 

Client/server network [SLC 2071]

Client/ server network is a type of network architecture that consists of at least one server and one or more clients or workstations, where users do their work. It provides central security administration and the network administrator is responsible for data security and other resources management of the network.

 

Peer-to-peer network [SLC 2071]

Peer-to-Peer network is a group of computers, which function both as servers and workstations to share data, information and other resources of the network. It lacks centralized network administration, where the network administrator needs to manage security on each computer. It provides no reliable security and might put data in higher risks.

 

 

 

 

Client/server network Vs Peer-to-peer network

 

Client/server network	Peer-to-peer network
There is a specific server and specific clients connected to the server.	Clients and server are not distinguished; each node act as client and server.
The client request for service and server respond with the service.	Each node can request for services and can also provide the services.
The data is stored in a centralized server.	Each peer has its own data.
The client-server are expensive to implement.	Peer-to-peer are less expensive to implement.

 

Network topology / LAN Topology - Bus, Ring, Star [Computer Science - Grade X - New Syllabus]

 

Network topology (LAN topology) [SLC 2064]  [SLC 2065 S] [SEE 2066 S] [SEE 2067 S] [SLC 2068]

[SLC 2070] [SEE 2072]  [SEE 2075U]
The arrangement or connection pattern of computers or nodes and other devices of the network is called network topology. The three basic topologies are bus topology, ring topology and star topology

 

Bus topology
The network topology in which computers and other devices are arranged in linear format which uses a common backbone or wire to connect all the computers and devices is called bus topology.

 

 

Diagram of bus topology [SEE 2067 S] [SLC 2069 S]

 

 

Advantages of bus topology [SEE 2073]

a)      It is easy to set up computers and other devices in bus topology, because all the devices are connected through a single wire.

b)     It requires fewer cable media, so it is cheaper than other topologies.

c)      It is easy to add new node to the network.

d)     Failure of one workstation does not affect other computers on the network.

 

Disadvantages of bus topology

a)     The whole network system collapses if the cable or backbone is damaged.

b)     The network slows down if additional computers are connected.

c)     The limited length of the cable in a network may restrict to connect the workstation or devices.

d)     It is difficult to find fault in this network topology.

 

Ring topology [MF 2076]

The network topology in which computers are connected in the shape of a circle without any end points is called ring topology. Each workstation contains two neighbours for communication or an input and output connections.

 

Diagram of ring topology [SEE 2072] [MF 2076]

 

Advantages of ring topology

i) It is easy it set up and configure.
ii) Each computer gets equal opportunity to access the network resources.
iii) It supports high data transmission rate.

iv) Performs better than a star topology under heavy network load.

 

 

Disadvantages of ring topology

i)Failure of any cable or single computers may affect the entire network.
ii) It is difficult to detect the errors.
iii) Adding/removing the devices affect the entire network.

iv) Much slower than an Ethernet network under normal load.

Star topology [SLC 2065] [U1]

The network topology in which all computers or other devices are connected through a central device through a central device called hub or switch is called star topology.

 

Diagram of star topology [SLC 2064] [SLC 2065] [U1]

Advantages of star topology

i) Easy to set up and configure.
ii) Failure of single computer or cable doesn’t affect the entire network.
iii) It is easy to find the fault.
iv) It is easy to extend to network by attaching new devices to the central devices.

 

Disadvantages of star topology

i) It requires more cable in comparison of bus topology so it is more costly.
ii) Failure of central devices (hub or switch) break down the whole system.

Types of Network - LAN, MAN, WAN [Computer Science - Grade X - New Syllabus]

 

Types of Network

a)      LAN (Local Area Network)

b)     MAN (Metropolitan Area Network)

c)      WAN (Wide Area Network)

 

LAN (Local Area Network)

A LAN is a type of network which covers small area i.e. within a room, building, or short distance by using cables or small wireless devices. It is controlled by a single organization. It uses private connection media. E.g.: network in a school, college or cyber cafe. The diameter is not more than a few kilometres. LAN offers bandwidth of 10-100 Mbps.

 

MAN (Metropolitan Area Network)

A MAN is a type of network which covers an entire city. It is controlled by single or group of organization. It uses private or public connection media. E.g.: interconnection between different branches on same branch and ISP providing internet services. It offers a number of network services compatible with bandwidth from 128 kbps to 1 Gbps.

 

WAN (Wide Area Network)

A WAN is a type of network which  connects two or more computers generally across a wide geographical area such as cities, districts, and countries. It is controlled by group of organization. It uses public connections media like telephone lines, satellite links or microwave system to connect several LANs and MANs.  E.g. internet. Data transmission in WAN is slower than LANs and WANs.

Software components of a computer network - Protocol, NOS, Device Driver [Computer Science - Grade X - New Syllabus]

 

Software components of a computer network

a)      Network protocol

b)     Network operating system

c)      Device driver

 

Network operating system [PMT 2075K]
Network operating system is a set of computer program that manages the resources on network. E.g. Novell network, Microsoft Windows NT, Linux, Unix etc.

 

Device driver

Device driver is a program that controls the functionality of the hardware device.

Hardware components of a Computer Network [Hub, Switch, Router, Bridge, Gateway [Computer Science - Grade X - New Syllabus]

 

Hardware components of a computer network (Elements of Network)

Physical parts and devices used to connect computers in the network environment are called hardware components. The hardware components of computer network are

a)      Computer system (Server or Workstation)           b) Network connectors               c) Network cables

d)    NIC Card                     e) MODEM                  f) Hub                                      g) Bridge

 h)     Switch                                    i) Router                       j) Gateway                                k) Repeater

 

Server

A server is the main computer that provides services, data and other resources to the other computers in the network environment. Network operating software used by server is Novell Netware, Linux, Unix etc. Different types of servers are file server, print server, application server etc.

 

Workstation
Workstation is a computer network that utilizes network resources. Network operating software used by workstation are Windows 98, Windows XP etc.

 

Node
Each computer or device of network is called node.

 

Router [MFT 2075]
Router is an intelligent device that connects two different networks which uses the address for filtering and forwarding the data as well as it has an ability to determine the best route for destination.

 

 

Network Interface Card (NIC) [SQE 2075K]
A Network Interface Card (NIC) is the adapter through which the computer is connected to the network. The function of NIC is to convert data into electronic signals and transfer them through cables and vice-versa. The advantage is to present the platform for a communication between the computers within a network.

 

Cable
Cables are commonly used media of physical channel for transmitting data between computers in network. Examples of cables are coaxial, twisted pair and fiber optic cable.

 

Connector
Connector is an interface between the NIC of the computer and the cable that passes data between computers in network. Examples of connectors are BNC used with coaxial cable, RJ 45 used with UTP cable, ST used with fiber optic cable etc.

 

Hub [MF 2076]

A hub is a network device with multiple points or ports which acts as a central point from where different computers and other devices are connected. It broadcasts all network data across each connection.

Hub is mostly used in physical star topology.

Switch [MF 2076]
A switch is a networking device that has multiple connecting ports which is often used interchangeably with the bridge.

 

Bridge

A bridge is a device that connects two or more similar types of network which filters the data or inspects incoming signals and decides whether to forward the signals or discard them.

 

Gateway
Gateway is an interconnecting device that connects two dissimilar networks

 

Repeater
Repeater is a device that amplifies the incoming signals, creates a copy of it and transmits the signal on network.

 

MODEM [MFT 2075]

MODEM is a device which is used to transfer the data of one computer to another computer using telephone lines.

The role of MODEM in data transmission is that it transfers data from one computer to another through telephone line. It also converts the digital signal into analog and vice versa.

 

Importance of MODEM [SLC 2064] [SLC 2071 S] [SEE 2073 U]

MODEM modulates the digital codes of the computer into analog signal, which then can travel through the telephone cable. At the receiving end the MODEM kept there will demodulate the analog signal to digital codes, which can be then understood and used by the receiving computer. In this way a MODEM makes the computer network possible.

 

Modulation

The process of translating digital signals of a computer to analog signals, which are then transmitted across the standard telephone lines, is known as modulation.

 

Demodulation

The process of translating analog signals from a phone line and converts then into digital signals for the computer is known as demodulation.

Computer Network - Advantages and Disadvantages [Computer Science - Grade X - New Syllabus]

 

Computer network [SLC 2066] [SLC 2068 S] [SLC 2069 S] [SLC 2070 S] [SLC 2071 S] [SEE 2074]

A computer network means two or more computers connected with each other to share data, hardware, software and other resources.

 

Advantages of computer network  [SLC 2065 S] [SLC 2069] [SLC 2071 S] [SEE 2075 S2] [MF 2076]

[MFT 2075]

a)      Computer in a network can access the network-connected hardware devices like printers, disk drives, etc.

b)     Data in a network environment can be updated from any computer. Updated data can be accessed by all computers on the network.

c)      Computers in a network system share different software packages.

d)     Information can be exchanged rapidly in computer network.

Disadvantages of computer network [SEE 2075 S2] [MF 2076] [MFT 2075]

a)      The sharing of information may leak the privacy of other clients.

b)     The networking cost is high

c)      If hardware or software malfunctions, it affects the whole network.

d)     Data and information may be stolen by computer hackers if the security of network is not reliable.

Reasons of keeping computers on the network [SLC 2070 S]

a)      To share hardware devices like printers, scanners, hard disks etc.

b)     To share data and information.

c)      To share software resources.

d)     To communicate with each other.