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Networks & viruses

presented by:Sartaj Butt


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NetworksA computer network is an

intercommunication of more than one

computer system & associated peripheral

devices located at the same/different

places.The interconnection is done

through a communication link & the link

is such that is totally transparent.Thetransparency of the communication linkis brought about by interfacing software

known as protocols.


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It provides country wide or

global connections viatelephone & satellites . Large

corporations that have officesworld wide use this type of

network. e.g: zee tv , star one ,DD news etc.


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VIRUScomputer viruses are spreading like a

disease now-a-days as the popularity

of computers is increasing day by day.

They are increasing in the countries

like india & Pakistan, which havecomputer markets.


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Computer viruses are nothing but a small

malicious program written either inassembly language or in system

programming language like c that

resides on the magnetic storage medium.Virus effects other healthy programs,they

can reside only in magnetic storage of

computers & thus infect it. e.g virusspreads when magnetic mediums of

computer come into contact.


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Classification of virusesThe maximum number of viruses are

designed forDOS at micro computer level.

these viruses can be further classified as under1.Boot infector virus: this virus reside in boot

sector of Floppy disk or Hard disk or the

partition table of Hard diskExample BRAIN,JOSHI etc


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2.File infector virus : this type of virus is

attached to the start or the end of

executable files. E.g.(exe or com).When the file is executed,the virus code

is first executed & resides in the RAM.

There after when any executable file is

run virus effects it.The virus effect either

.exe or .com files or both. E.g..VIENNA (infects only .com files)

DARK AVENGER (infects both types of

files)


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3.Dos System Infector Virus: thisvirus effects operating system of DOS

(system files of DOS).These effect thefiles like IBMBIOS.COM ,

IBMDOS.COM &

COMMAND.COM.


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Following are some anti virus

software names:

Nashot , Red Armour , Quick Heal ,SmartDog , VirusScan , UtScan ,

UnVirus , TNT etc

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