What is Network Topology? Explain Ring, Bus, Star, Mash Topology. Network Topology.
Each computer or device in a network is called a node. The geometrical arrangement of computer resources, remote device, communication facilities is known as network topology.
Two or more device connect to a link; two or more links form a topology. The topology of a network is the geometric representation of the relationship of all the links and linking devices to one another.
There are four basic topologies possible ;
1) BUS :
It is a multipoint topology. In a Bus Network, each computer is connected to a single communication cable.
Node are connected to the bus cable by drop lines and taps. A drop line is a connection running between the device and main cable. As a signal travels along the backbone, some of its energy is transformed into heat. So it becomes weaker and weaker as it has to travel farther distance. So there is a limit on the number of taps a bus can support and so the distance between these taps.
i) Easy to Installation
ii) Cost effective as less numbers of cables are required
i) Identification and Isolation of fault is difficult
ii) Adding new device is difficult
iii) Signal reflection at the taps can cause degradation in equality
iv) A fault in cable stops all transmission.
2) STAR :
In a star Topology, each device has a dedicated point-to-point link only to a central controller, called as a hub. The devices are not directly linked to one another. Unlike a mesh topology, a start topology does not allow direct traffic between devices. If one device want to send data to another, it sends it to the controller, which then relays to other device.
i) Less expensive than mesh topology as each device needs only 1 link and one I/O port to connect it to any number of others.
ii) Easy to install and reconfigure.
iii) Robustness : If one link fails, only that link is affected. Other links remains active.
iv) Easy fault identification and fault isolation.
i) If hub tails then whole network is in problem.
In a ring topology, each device has a dedicated point-to-point connection only with the two devices on either side of it. A signal is passed along the ring in one direction, from device to device, until it reaches its destination. Each device in the ring incorporates a repeater. When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along.
i) Easy to install and reconfigure
ii) Each device is linked only to its two neighbours, So adding or deleting a device requires changing only two connections.
iii) Fault isolation is simplified
i) A break in a ring can fail the whole network
ii) Unidirectional traffic is a disadvantage
4) MESH :
In a mesh Topology, every device has a dedicated point-to-point link to every other device. Dedicated means that the link carries traffic only between the two devices it connects. A fully connected mesh networks has n(n-1)/2 physical channels to link n devices
i) Use of dedicated links guarantees that each connection can carry its own load eliminating the traffic problems.
ii) It is robust. It one link becomes unusable, it does not destroy the entire system.
iii) Other advantage is privacy or security. When every message travels along a dedicated line, only the intended recipient sees it.
iv) It makes fault identification and fault isolation easy.
i) Amount of cabling and the number of I/O ports required are large. So cost increases.
ii) Hardware required to connect each link can be very expensive.
Q Explain the term ‘Network’. Explain LAN, WAN, MAN. In brief.
Networks can be classified according to their scale i.e. the distance or area they cover.
There can be four types of networks :
a) Local Area Networks (LAN)
b) Metropolitan Area Network s (MAN)
c) Wide Area Network (WAN)
LAN Stand for Local Area Networks. LAN is two or more computers directly linked within a small well defined area such as a room, office building, or a campus. A LAN can be made up of only microcomputers or any combination of microcomputer and large system. Main benefit of a LAN is the reduction of hardware and software costs because user can share several computers
There communication speed ranges from 10 Mbps to 100 Mbps (Mega bit per second)
LAN’s can be of two types :
i) Server based LAN’s : Here, a separate computer is set aside as the server which processes requests from many clients or workstations.
ii) Peer –to-poor LAN’s : All computers on the networks act as resource provides and users.
MAN Stand for Metropolitan Area Networks (MAN’s). A metropolitan Area Networks, it serves a role similar to an internet service provider. But a MAN network is a network that is larger than LAN. It is called metropolitan since it normally covers the area of city. Difference hardware and transmission media are often used in MAN.
A Man typically cover area of between 5 to 50 Km diameter.
WAN Stand for Wide Area Networks. A Wide area network is two or more geographically dispersed computers, linked by communication facilities such as telecommunication or microwave relays. WAN network is also called “LONG HAUL NETWORK”.
Typically, a WAN is a connection of Multiple LAN. In a same case the WAN may not include any LAN’s; it could also be separate networks.
A Special designation has also been given to two specific WAN categories :
• Enterprise : An enterprise network connects all LAN’s of a single organization. The Term is normally used for networks connecting extremely large organizations.
• Global : By definition a global network is one that spans the earth. While global networks may not cover the entire globe, they cross multiple national boundaries and may include the networks of several organizations.
Q.) Write a short notes on
a) Coaxial Cable
A coaxial cable consists of many small cables in a protective cover. The cover shield the cable from physical dangers as well as from electromagnetic interference. Within the cover the various cable are shielded from interference with one another. Coaxial cables are used in communication networks that require many simultaneous communication links. Each coaxial cable can provide more than 5000 links.
The initial installation of coaxial cable is relatively simple.
As a copper wire media, coaxial cable suffers from high attenuation, but at a much lower rate than either variety of twisted pair. Using current LAN technology, the effective range of coaxial cable is in the low thousands of meters.
There are two type of coaxial cables :
Baseband and broadband. A baseband coaxial cable transmits a simultaneous signals using different frequencies. A baseband cable transmits a single stream of digital data at a very high communication rate. It is mainly used for local area networks. A base band coaxial cable can carry only an analog signal, so it must be used in conjunction with a modem. It is more complex to use in a network.
a) Microwave :
Microwave is also a type of analog communication channel. Microwave signals are transmitted through the atmosphere rather than through wire cables, similar to the way radio and television signals are transmitted. Microwave signals must be transmitted in a straight line, they do not bend around the curve of the earth. Transmitter stations redirect and boost the signals.
The data may be beamed to a communications satellite that acts as a reflector by accepting signals from one point on earth and returning the same signals to some other point or earth. Compared to wire cable, microwave has a much lower error rate, making it more reliable. The only disadvantage is the high cost of ground stations and satellites to support a microwave network.
c) Fiber Optics :
Fiber Optics are very reliable communication channels are they transmit data in digital form. They use light impulses that travel through clear flexible tubing. A signal glass fiber in thinner than the size of a human hair and it can transmit all the characters in dozens of books of the same size of this one across the country in a single second.
Fiber optics can transmit data at very high speed with no errors. Unlike wire cables, fiber optic cables are not subject to electrical interference. They do, however required repeaters to read and boost the signal strength because light pulses will lose signal strength over long distance.
The nature of fiber optic cable poses installation problems. Every fiber junction, splice or connection must be made with extreme care to ensure that the light path is unobstructed. Installers must be careful not be excessively stretch or bend the fiber.
Fiber optic cable have extremely low attenuation rates. The amount of attenuation various depending upon the operating wavelength, but effective ranges are usual ly measured in kilometers. Therefore fiber optic cable attenuates much less than any copper wire transmission medium.
E-commerce means buying and selling of goods and services over the internet. This include both business to business and business to consumer (B2C) transactions. E-Commerce deals with the exchange of money for soft or hard goods and services.
E-Commerce is a general concept covering any form of business transaction or information exchange executed using information and communication technologies. E-Commerce take place between companies, between companies and their customers or between companies an public administration. Electronic commerce includes electronic trading of goods, services and electronic material.
E-commerce is like so much in the areas of business and information system the subject of numerous definitions.
Some authors see e-commerce as largely or entirely an internet phenomenon.
Seddon (1997) has suggested that the world has just entered a third new phase in the evolution of IT capabilities : the internet era. The suggestion divides the evolution of information technology into 20 year period
1955 – 1974 The electronic Data processing era
1975 – 1994 The management information system era
1995 – 2014 The Internet era
Features of E-Commerce :
1) It include electronic trading of goods and services
2) It can be applied to trade cycle
3) It is fasted growing web page application
4) It completes the business transaction in few minutes
5) It offers services to customer for 24 hr.
6) It increases the efficiency of the trade
7) It provides diverse types of product
8) It offers services for all days
9) It extends the scope of business
10) It provides better customer services
11) It uses EDI technique for regular business transaction
12) It offers qualitative products at reasonable price
13) It provides facility of online transaction
14) Use of electronic cash, cheques & smart cash cards are notable features.
Function of E-Commerce :
The four functions of E-Commerce are :
• Communication : The aim of communication function is to deliver information and/or documents to facilities business transitions. For ex – e-mail.
• Process Management : The process management function covers the automation & improvements of business processes.
• Service Management : Service Management function is the application of technology to improve the quality of service.
• Transaction capabilities : Transaction capabilities provides the ability to buy/sell on the internet or some other on-line service.
Benefits of E-Commerce :
1) Reduced costs to buyers from increased competition in procurement, as more suppliers are able to compete in an electronically open marketplace.
2) Reduced costs to suppliers by electronically accessing on-line database of bid opportunities by online abilities to submit bids, and by on-line review of awards.
3) Reduced errors, time and overhead costs in information processing by eliminating requirement for reentering data.
4) Reduced inventories, as the demand for goods and services are electronically linked through just in time inventory and integrated manufacturing techniques.
5) Reduced time to complete business transations, specifically reduced time from delivery to payment.
6) Better quality of goods as standardized specifications and increased competition; also better variety expanded markets and the ability to produce customized goods.
7) Increased access to a client base. Identifying and locating new clients and new markets.
8) Cost-effective document and fund transfer.
9) Faster time to market as business processes are linked, eliminating time delay between steps within the process.
Impact of E-Commerce of Business :
E-Commerce is impacting in a broader way on most of the business organizations. It is to decide how our organization is equipped to use e-commerce technology. This is the most important and difficult part of defining our strategy, because of the multifaceted nature of e-commerce and the various alternative it presents. The variables is this issue involved are :
• Need of change
• Risk avoidance
• State of the current operation
• Competition and financial stability
These will change the geography of our e-commerce landscape.
The factors and components that affect our strategy development is shown in the figure.
Traditional Commerce Vs E-Commerce :
E-commerce involves combination of :
• Information technology
• Telecommunications technology
• Business processes
Advantages of E-Commerce :
1) Companies are interested in electronic commerce because it can help in the increase of profit.
2) Electronic commerce can increase sales, decrease recurring costs and eventually end up in higher profits.
3) Unlike making advertisement in billboards, sending product catalogues to different customers through post, advertising can be easily done on the web at a lesser cost.
4) E-Commerce not only increases sales opportunities, but it also increases buying opportunities.
5) E-Commerce provides buyers with a wider range of choices than traditional commerce as it can consider many different product and services form a wider variety of sellers through the web.
6) E-commerce can be extended for the welfare of the society. Particularly, e-governance transaction in the form of electronic bill payment to the government, tax refunds to the public.
Disadvantages of E-Commerce :
1) E-Commerce possesses disadvantages as well. Some businesses will never do business electronically,
2) Items that need to be inspected through touch and smell are not possible to sell through e-commerce websites.
3) High cost items such as custom-designed jewellary and antiques is not possible to inspect adequately form a different geographical location, regardless of the virtual reality technologies that might be in use.
4) One major disadvantages of e-commerce today is the rapidly developing pace of the underlying technologies.
5) Perishable grocery products, such as fruit and vegetables are harder to sale electronically, as customer want to examine and select specific items that are still fresh and appealing.
Electronic Commerce and the Trade Cycle
E-commerce can be applied to all, or to different phases, of the trade cycle. The trade cycle varies depending on :
• The nature of the organization involved.
• The frequency of trade between the partners to the exchange
• The nature of the goods or services being exchanged
The trade cycle has to support :
• Finding goods or services appropriate to the requirement and agreeing the terms of trade.
• Placing the order, taking delivery and making payment
• After-sales activities such as warrantee, service etc.
There are numerous version of the trade cycles depending on the factors outlined above and for may transaction, further complicated by the complexities of international trade.
• Regular, repeat transactions between commercial trading partners
• Irregular transaction between commercial trading partners where execution and settlement are separated
• Irregular transaction in once-off trading relationships where execution and settlement are typically combined.
An electronic market is an inter-organizational information system that provides facilities for buyers and sellers to exchange information about price and product offerings. The electronic market is primarily about the search phase of the trade cycle. The electronic market is most effective in assisting the buyer in a commodity market where product are essentially identical across all sellers.
“The effect of an electronic market in a commodity market is a more efficient distribution of
information which causes decreasing profit possibilities for sellers.”
Usage of E-Market :
E-Market gives easy and fast access to data for product and services to the customers. The main use of E-Market is spreading and publishing information for the use of customers. E-Market is also referred as search phase of the trade cycle.
The best example of E-Market is airline tickets booking or enquiry. The other E-market system is stock market.
Airline booking system and stock market system. Both systems helps users to search information, marking enquiry or to check the current status.
E-Market helps to serve or to solve customer’s queries or problem. Models of E-Market are to different types that are :
1. Virtual superstores
2. Electronic Storefronts to existing services
3. Bid/ask marketplaces
4. Virtual order centers
5. Intranet-based centers
6. Intranet-based electronic business communities
7. Virtual trading marketplaces.
1. No need of Middlemen : e-market is direct online between producer and customer. Hence there is no need of middle man in the distribution system which leads to saving in cost of commission.
2. Trading at low cost : Trading on internet require less charges. There for operation cost of trading is very low as compared to traditional commerce
3. Expansion of market : Worldwide buyer and sellers joint hands in market.
4. Increase in Profit : Managing marketing activities through internet is profitable. It allows selling the products in many countries.
5. Searching Cost : It saves searching cost by providing all information at a time. It also decrease overall cost of the product.
1. Insufficient database : database with regard to producer, customer is not sufficient. There fore information from all types of customers and suppliers is still not available on internet.
2. Lack of availability of consumer goods : Consumer’s goods for daily needs are not completely available on E-Market. Daily needs such as vegetables, fruits, breads, milk are not available on E-market.
3. Mindset of customers : Majority of the customers do not know how to use internet. They are not fully aware about the benefits of E-commerce. Therefore they like the traditional approach of buying and selling. Today we can easily notice that majority of the people would like to visit market place for purchasing the goods, this trend shows that the majority of the customers would like to continue with the traditional market and not E-market.
4. Skill person : To handle this system.
Future of E-Market :
The evolution to more open and interoperable electronic market place will depends upon the mass use of internet as E-market uses internet, co-operation between e-market availability of electronic business rules. On the basis of these E-market can have following future :
1. The use of Internet will make users aware for E-market and its use which leads to the mass use of E-market.
2. Instead of visiting travel agent, customer can visit online ticket booking of railway or airline website. It provides information of flights schedules or seat availability and can be book ticket
3. Customer can search online shops for the required product and services which help to get these product and services in low price without any middlemen.
4. Within a vertical industry. For Ex. a consumer would be able to manage all financial holdings across the various financial institutions that are maintaining them.
5. Across co-operating industries, but focused on a uniquely identified process.
6. The E-market providers can make their services “Open” to the available E-Market.
Electronic mail, most commonly referred to as email or e-mail since c. 1993,is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the same time, in common with instant messaging. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need connect only briefly, typically to a mail server, for as long as it takes to send or receive messages. Historically, the term electronic mail was used generically for any electronic document transmission. For example, several writers in the early 1970s used the term to describe fax document transmission. As a result, it is difficult to find the first citation for the use of the term with the more specific meaning it has today.
An Internet email message[NB 1] consists of three components, the message envelope, the message header, and the message body. The message header contains control information, including, minimally, an originator's email address and one or more recipient addresses. Usually descriptive information is also added, such as a subject header field and a message submission date/time stamp.
Electronic mail predates the inception of the Internet and was in fact a crucial tool in creating it, but the history of modern, global Internet email services reaches back to the early ARPANET. Standards for encoding email messages were proposed as early as 1973 (RFC 561). Conversion from ARPANET to the Internet in the early 1980s produced the core of the current services. An email sent in the early 1970s looks quite similar to a basic text message sent on the Internet today.
Email is an information and communications technology. It uses technology to communicate a digital message over the Internet. Users use email differently, based on how they think about it. There are many software platforms available to send and receive. Popular email platforms include Gmail, Hotmail, Yahoo! Mail, Outlook, and many others.
E-learning (or eLearning) is the use of electronic media, educational technology and information and communication technologies (ICT) in education. E-learning includes numerous types of media that deliver text, audio, images, animation, and streaming video, and includes technology applications and processes such as audio or video tape, satellite TV, CD-ROM, and computer-based learning, as well as local intranet/extranet and web-based learning. Information and communication systems, whether free-standing or based on either local networks or the Internet in networked learning, underlie many e-learning processes.
E-learning can occur in or out of the classroom. It can be self-paced, asynchronous learning or may be instructor-led, synchronous learning. E-learning is suited to distance learning and flexible learning, but it can also be used in conjunction with face-to-face teaching, in which case the term blended learning is commonly used.
Finance Service : Financial services are the economic services provided by the finance industry, which encompasses a broad range of organizations that manage money, including credit unions, banks, credit card companies, insurance companies, accountancy companies, consumer finance companies, stock brokerages, investment funds, real estate funds and some government sponsored enterprises.
E-Finance is defined as “The provision of financial services and markets using electronic communication and computation”. In this paper we outline research issues related to e-finance that we believe set the state for further work in this field. Three area are focused on these are the use of electronic payments system, the operation of financial services firms, and the operation of financial markets A number of research issues are raised. For exam is the widespread use of paper based checks efficient? Will the financial services industry be fundamentally changed by the advent of the internet? Why have there been such large difference in changes to market microstructure across different financial markets?
E-Banking : Online banking is an electronic payment system that enables customers of a financial institution to conduct financial transactions on a website operated by the institution, such as a retail bank, virtual bank, credit union or building society. Online banking is also referred as Internet banking, e-banking, virtual banking and by other terms.
To access a financial institution's online banking facility, a customer with Internet access would need to register with the institution for the service, and set up some password (under various names) for customer verification. The password for online banking is normally not the same as for telephone banking. Financial institutions now routinely allocate customers numbers (also under various names), whether or not customers have indicated an intention to access their online banking facility. Customers' numbers are normally not the same as account numbers, because a number of customer accounts can be linked to the one customer number. The customer can link to the customer number any account which the customer controls, which may be cheque, savings, loan, credit card and other accounts. Customer numbers will also not be the same as any debit or credit card issued by the financial institution to the customer.
To access online banking, a customer would go to the financial institution's secured website, and enter the online banking facility using the customer number and password previously setup. Some financial institutions have set up additional security steps for access to online banking, but there is no consistency to the approach adopted.
Online shopping or e-shopping is a form of electronic commerce which allows consumers to directly buy goods orservices from a seller over the Internet using a web browser. Alternative names are: e-web-store, e-shop, e-store, Internet shop, web-shop, web-store, online store, online storefront and virtual store. Mobile commerce (or m-commerce) describes purchasing from an online retailer's mobile optimized online site or app.
An online shop evokes the physical analogy of buying products or services at a bricks-and-mortar retailer or shopping center; the process is called business-to-consumer (B2C) online shopping. In the case where a business buys from another business, the process is called business-to-business (B2B) online shopping. The largest of these online retailing corporations are Alibaba, Amazon.com,and eBay. Retail success is no longer all about physical stores. This is evident because of the increase in retailers now offering online store interfaces for consumers. With the growth of online shopping, comes a wealth of new market footprint coverage opportunities for stores that can appropriately cater to offshore market demands and service requirements.
Several dimensions and factors influence the definition of e-governance or electronic governance. The word “electronic” in the term e-governance implies technology driven governance. E-governance is the application of information and communication technology (ICT) for delivering government services, exchange of information communication transactions, integration of various stand-alone systems and services between government-to-customer (G2C), government-to-business (G2B), government-to-government (G2G) as well as back office processes and interactions within the entire government framework. Through e-governance, government services will be made available to citizens in a convenient, efficient and transparent manner. The three main target groups that can be distinguished in governance concepts are government, citizens and businesses/interest groups. In e-governance there are no distinct boundaries.
Generally four basic models are available – government-to-citizen (customer), government-to-employees, government-to-government and government-to-business.
Difference between E-Government and E-Governance
Both the terms are treated to be the same, however, there is some difference between the two. "E-government" is the use of the ICTs in public administration - combined with organizational change and new skills - to improve public services and democratic processes and to strengthen support to public. The problem in this definition to be congruence definition of e-governance is that there is no provision for governance of ICTs. As a matter of fact, the governance of ICTs requires most probably a substantial increase in regulation and policy-making capabilities, with all the expertise and opinion-shaping processes along the various social stakeholders of these concerns. So, the perspective of the e-governance is "the use of the technologies that both help governing and have to be governed". ThePublic-Private Partnership (PPP) based e-governance projects are hugely successful in India. United Telecoms Limited known as UTL is a major player in India on PPP based e-governance projects . Each project had mammoth state wide area networks in these states.
E-governance is the future, many countries are looking forward to for a corruption-free government. E-government is one-way communication protocol whereas e-governance is two-way communication protocol. The essence of e-governance is to reach the beneficiary and ensure that the services intended to reach the desired individual has been met with. There should be an auto-response to support the essence of e-governance, whereby the Government realizes the efficacy of its governance. E-governance is by the governed, for the governed and of the governed.
Establishing the identity of the end beneficiary is a challenge in all citizen-centric services. Statistical information published by governments and world bodies does not always reveal the facts. The best form of e-governance cuts down on unwanted interference of too many layers while delivering governmental services. It depends on good infrastructural setup with the support of local processes and parameters for governments to reach their citizens or end beneficiaries. Budget for planning, development and growth can be derived from well laid out e-governance systems
Computer Application in Business and Industry :
With information technologies a ubiquitous part of today's business world, business computer applications are one of the most fundamental skills to be learned by anyone entering the workforce. Training at all levels is readily available through community and technical colleges, universities, business schools, software companies and online. Learn about some of the courses offered.
As is the case with most of computer graphics, the Computer-Aided Design (CAD) discipline can trace its beginnings to the Sketchpad system developed by Ivan Sutherland in 1963.
CAD/CAM : Computer aided Design/Computer Aided Manufacture are two systems that tend to work together. Computer Aided Design helps design products on computers, rather then having to create endless drawing. The system can create realistic 3D images of the finished project.
CAD also allow virtual testing of the product before it is actually made, dramatically reducting load time and minimizing waste in new product development.
CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing. CAD output is often in the form of electronic files for print, machining, or other manufacturing operations.
As CAD acts together with CAM, it outputs are designed to optimize designs for efficient manufacture with CAM system.
CAM uses computer to control tooling such as CNC and other robotized machinery. Benefits would be expected to include reliance on labour, in other words it is more capital intensive. In many cases, CAM facilities the manufacture of designs that would have been impossible without this technology.
Scientific Application :
Scientific Computer Applications Inc. (SCAI) is a privately held, American company based in Tulsa, Oklahoma. SCAI develops and markets scientific software focused on the Oil exploration and production segment of the petroleum industry.
Scientific Computer Applications, Inc. (SCAI) was established in 1969 as an Oil & Gas Consulting firm by Professional engineering Petroleum Consultant Richard Banks, a graduate of the Colorado School of Mines and the University of Texas.
SCAI markets contour map software that generates single surface, multiple surface, contour mapping and Reservoir Integration applications for the Personal computer.
Computer science is the scientific and practical approach to computation and its applications. It is the systematic study of the feasibility, structure, expression, and mechanization of the methodical procedures (or algorithms) that underlie the acquisition, representation, processing, storage, communication of, and access to information, whether such information is encoded as bits in a computer memory or transcribed in genes and protein structures in a biological cell. A computer scientist specializes in the theory of computation and the design of computational systems.
Office Automation : Office automation refers to the varied computer machinery and software used to digitally create, collect, store, manipulate, and relay office information needed for accomplishing basic tasks. Raw data storage, electronic transfer, and the management of electronic business information comprise the basic activities of an office automation system. Office automation helps in optimizing or automating existing office procedures..
The backbone of office automation is a LAN, which allows users to transmit data, mail and even voice across the network. All office functions, including dictation, typing, filing, copying, fax, Telex, microfilm and records management, telephone and telephone switchboard operations, fall into this category. Office automation was a popular term in the 1970s and 1980s as the desktop computer exploded onto the scene.
1. Office automation can get many tasks accomplished faster.
2. It eliminates the need for a large staff.
3. Less storage is required to store data.
4. Multiple people can update data simultaneously in the event of changes in schedule
What is Virus ?
A Virus is a software program that attaches itself to another program in computer memory or on a computer disk. Individuals for a number of different reasons wrote these software programs. These programs wait for a particular date or chain of events when they will attempt to damage data, cause the computer to crash or display messages. The primary goal of a virus or display to something and travel with it. They move to disks, to e-mail and across modems to move as quickly as possible and infect a large number of system.
Type of Virus :
File / Program : pale infections will only appear in executable files. Primarily *.com and *.exe, However they also can exist in *.drv, *.dll, *.Bin, *.ovl, *.386 or *.sys.
Boot Sector : Boot sector infections attack the Master boot record of the hard drive or the boot sector of a floppy disk. These viruses lodge themselves and do the damage whenever the computer is booted.
Multi partite : Multi partite viruses go after both the boot sector and files
Macro : Macro based viruses infect documents written in Microsoft word. This is the only virus that infects PC and Macintosh computers.
Virus Effects :
1) Increase the file size
2) Slow down the system
3) Corrupt File.
4) Mark good sector bad.
5) Format the hard disk, thus destroying data
6) Renaming all files with a single name and many more.
7) interface with the display on the screen.
8) Destroy the FAT( File Allocation Table
Anti Virus :
These are the programs that are used to remove viruses and cure the files. These are various type of software programs available that are used to detect and remove the virus. These anti Viruses are installed in the computers. Whenever the virus is detected the antivirus warns the user about the presence of virus in the floppy or hard disk. These programs automatically check the machine at startup. While checking it scans all the files, folders in the hard-disk. Some of the antivirus software are :
Norton Antivirus, MCAfee, Red Alert, Dr. Soloman, Quick Heal, PC Clean, smartDog etc.
Types of Anti Virus Programs :
Antivirus programs are mainly classified into three types :
1) Scanners : they are used to scan the virus from the hard disk or floppy diskette and detect any virus.
2) Antidotes (solution/cure/Answer) : they are used to destroy any virus they find.
3) Vaccines : Vaccines are program that protect a disk from getting infected.
The term firewall originally referred to a wall intended to confine a fire or potential fire within a building. Later uses refer to similar structures, such as the metal sheet separating the engine compartment of a vehicle or aircraft from the passenger compartment.
Firewall technology emerged in the late 1980s when the Internet was a fairly new technology in terms of its global use and connectivity. The predecessors to firewalls for network security were the routers used in the late 1980s:
In computing, a firewall is a network security system that controls the incoming and outgoing network traffic based on applied rule set. A firewall establishes a barrier between a trusted, secure internal network and another network (e.g., the Internet) that is assumed not to be secure and trusted. Firewalls exist both as a software solution and as a hardware appliance. Many hardware-based firewalls also offer other functionality to the internal network they protect, such as acting as a DHCP server for that network.
Many personal computer operating systems include software-based firewalls to protect against threats from the public Internet. Many routers that pass data between networks contain firewall components and, conversely, many firewalls can perform basic routing functions.
Spyware is software that aids in gathering information about a person or organization without their knowledge and that may send such information to another entity without the consumer's consent, or that asserts control over a computer without the consumer's knowledge.
"Spyware" is mostly classified into four types: system monitors, Trojans, adware, and tracking cookies. Spyware is mostly used for the purposes of tracking and storing Internet users' movements on the Web and serving up pop-up ads to Internet users.
Whenever spyware is used for malicious purposes, its presence is typically hidden from the user and can be difficult to detect. Some spyware, such as keyloggers, may be installed by the owner of a shared, corporate, or public computer intentionally in order to monitor users.
While the term spyware suggests software that monitors a user's computing, the functions of spyware can extend beyond simple monitoring. Spyware can collect almost any type of data, including personal information like Internet surfing habits, user logins, and bank or credit account information. Spyware can also interfere with user control of a computer by installing additional software or redirecting Web browsers. Some spyware can change computer settings, which can result in slow Internet connection speeds, un-authorized changes in browser settings, or changes to software settings.
Routes of infection
Spyware does not necessarily spread in the same way as a virus or worm because infected systems generally do not attempt to transmit or copy the software to other computers. Instead, spyware installs itself on a system by deceiving the user or by exploiting software vulnerabilities.
Most spyware is installed without users' knowledge, or by using deceptive tactics. Spyware may try to deceive users by bundling itself with desirable software. Other common tactics are using a Trojan horse. Some spyware authors infect a system through security holes in the Web browser or in other software. When the user navigates to a Web page controlled by the spyware author, the page contains code which attacks the browser and forces the download and installation of spyware.
The installation of spyware frequently involves Internet Explorer. Its popularity and history of security issues have made it a frequent target. Its deep integration with the Windows environment make it susceptible to attack into theWindows operating system. Internet Explorer also serves as a point of attachment for spyware in the form ofBrowser Helper Objects, which modify the browser's behavior to add toolbars or to redirect traffic.
Effects and behaviors
A spyware program is rarely alone on a computer: an affected machine usually has multiple infections. Users frequently notice unwanted behavior and degradation of system performance. A spyware infestation can create significant unwanted CPU activity, disk usage, and network traffic. Stability issues, such as applications freezing, failure to boot, and system-wide crashes are also common. Spyware, which interferes with networking software, commonly causes difficulty connecting to the Internet.
In some infections, the spyware is not even evident. Users assume in those situations that the performance issues relate to faulty hardware, Windows installation problems, or another infection. Some owners of badly infected systems resort to contacting technical support experts, or even buying a new computer because the existing system "has become too slow". Badly infected systems may require a clean reinstallation of all their software in order to return to full functionality.
Moreover, some types of spyware disable software firewalls and anti-virus software, and/or reduce browser security settings, which further open the system to furtheropportunistic infections. Some spyware disables or even removes competing spyware programs, on the grounds that more spyware-related annoyances make it even more likely that users will take action to remove the programs.
Remedies and prevention
As the spyware threat has worsened, a number of techniques have emerged to counteract it. These include programs designed to remove or block spyware, as well as various user practices which reduce the chance of getting spyware on a system.
Nonetheless, spyware remains a costly problem. When a large number of pieces of spyware have infected a Windows computer, the only remedy may involve backing up user data, and fully reinstalling the operating system. For instance, some spyware cannot be completely removed by Symantec, Microsoft, PC Tools.
Many programmers and some commercial firms have released products dedicated to remove or block spyware. Programs such as PC Tools' Spyware Doctor, Lavasoft's Ad-Aware SE and Patrick Kolla's Spybot - Search & Destroy rapidly gained popularity as tools to remove, and in some cases intercept, spyware programs. On December 16, 2004, Microsoft acquired the GIANT AntiSpyware software, rebranding it as Windows AntiSpyware beta and releasing it as a free download for Genuine Windows XP and Windows 2003 users. (In 2006 it was renamed Windows Defender).
How Anti-Spyware Software Works
Anti-spyware programs can combat spyware in two ways:
1. They can provide real-time protection in a manner similar to that of anti-virus protection: they scan all incoming network data for spyware and blocks any threats it detects.
2. Anti-spyware software programs can be used solely for detection and removal of spyware software that has already been installed into the computer. This kind of anti-spyware can often be set to scan on a regular schedule.