Saturday 18 July 2015

Computer Network Topologies


             Computer Networking is  a set of devices connected in a particular media links.A device can be a computer,printer or any other device that is able to send or receive data on the network.The links connected in devices are called Communication channels.Also computer networks are used for data communication.There are five basic components of data communication Massage, Sender, Receiver, Medium & Protocol.Network allows to share access information devices.
               The way a network is laid out, either physically or logically is refers as Topology. Topology are divided in five types:-
                                                                                 

                      By using this Topology we can transfer data from one system to another system.Apart from this there is an another topology name is Hybrid Topology, this topology is combination of all topology connected with each other.In this topology there is signal transmission this transmission of signal is known as Transmission Modes.There are three transmission modes Simplex, Half duplex, Full duplex which are described in the form of diagram below:-
Transmission Modes


Sunday 12 July 2015

Computer Virus

 
Computer virus representation(abstract)
              A computer virus is nothing but a malicious code that replicates itself again and again in a specified manner.A computer virus commonly comes in a system when an email attachment is downloaded from our email account this will replicates all the contents of our attachment and some times corrupt the file before opening it.

               Virus is a term that stands for "Vital Information Resources Under Seize" this means a computer virus is runs without wishes of user and corrupt over all system files or impotent documents on the systems memory.

                The overall memory is occupied by the virus and hard disk may be corrupted because of viruses. There are various types types of viruses listed below:-

  1. Boot sector viruses
  2. Traditional file viruses
  3.  Document or macro viruses
  4. 32-bit file viruses
  5. Worms
  6. Trojan horses