Computer networking
- 2. Overview of Computer Network A computer network is a collection of interconnected computers and other devices to share data and other resources.
- 3. Advantages of Computer network Resource Sharing The primary use of a network is to share among users applications, programs, data. For example, sharing database, audio and video files, printers and scanners etc. We can share data and applications to devices connected to network irrespective of their physical location.
- 4. Reliability of data Reliability means backing up of data, i.e., data can be copied and stored on multiple computers. In a network system, all computers are connected to each other, so the chances of data getting lost are very less.
- 5. Central Storage of data Files can be stored on a central node that can be shared and made available to each and every user in an organization. With centralized processing, data is stored and retrieved from a single central location.
- 6. Types of Networks A computer network may be small or big depending upon the numbers of devices linked together. Networks vary in size, they can be on a table, in a room, building, city, country, across continents or around the world. ▪ PAN ▪ LAN ▪ MAN ▪ WAN
- 7. Personal Area Netw0rk (PAN) The network that belongs to a single person or user is known as PAN. It is a small network and may include wireless keyboard and mouse, Bluetooth-enabled headphones, wireless printers and TV remotes.
- 8. Local Area Network (LAN) It is privately owned computer network covering a small geographical area, like a home, office or a building such as school. Its range is of few kilometres and its key purpose is to share resources.
- 9. Metropolitan Area Network (MAN) MAN’s network is larger and can cover a city and its surrounding areas. A MAN is typically owned and operated by a single entity such as government body or a large corporation. A good example is the interconnected offices of a Multinational corporation.
- 10. Wide Area Network (WAN) AWAN interconnects all the computers across the world. It is a telecommunication network which spreads over a large geographical area across countries and continents. The internet is the largest WAN spanning the entire planet.
- 11. Transmission Media All the computers or communicating devices in the network must be connected to each other to communicate and share data and other resources. To connect to each other, there must be some medium over which the data can travel from one computer to another. This is termed as Transmission media or Channel. Wired Network Wireless Network
- 12. Wired Network/Media Twisted Pair Cable It is the most common type of media which consists of four insulated pairs of wires twisted around each other. It is available in ShieldedTwisted Pair (STP) or UnshieldedTwisted Pair (UTP).
- 13. Coaxial Cable It consists of two solid insulated conductors that share a common axis.The inner conductor is a straight wire surrounded by wired mesh, each separated by some kind of foil or insulator. It is mostly used in CableTV transmission.
- 14. Optical Fibre Cable It consists of long, thin strands of glass or glass-like material and carries light. It transmits light (photons) instead of electricity over glass or plastic “fibres”. Fibre optics are very good for high- speed, high capacity data transmission due to lack of attenuation.
- 15. Wireless Media RadioWaves Radio Communication uses radio frequencies in range of 3 KHz to 3 GHz. These are used for communication over distances ranging from a few metres to an entire city. Cordless phones, garage door openers, etc., are examples of radio wave transmission.
- 16. Microwaves Microwave signal are used to transmit data without the use of a cable. It is a line of sight transmission as signal travels in a straight line. In big cities where land is very costly, microwave antennas can be put on top of highrise buildings and communication can be started in a short time.
- 17. InfraredWaves Infrared wave network allows devices to communicate within a short range of approx. 5 metres using wireless signals. These signals do not cross through solid objects, that's why you cannot controlTV in another room with the remote in your hand.
- 18. Bluetooth Bluetooth is a wireless technology used for creating personal networks operational within a range of 10 metres. It uses 2.4 GHz unlicensed band. It can connect upto eight devices simultaneously, but data transfer rate is slow (upto 1 Mbps).
- 19. Network Devices Network devices are also termed as communication devices and they constitute a data communication network. Other than the transmission media, many other devices are requires to form computer networks.
- 20. Network Interface Card (NIC) It is a device that enables a computer to connect to a network and communicate. A computer communicates with other devices on a network with the help of an NIC only. NIC works with MAC address.
- 21. Hub A Hub is an electronic device that connects several nodes to form a network and redirects the received information to all the connected nodes in broadcast mode. It connects multiple computers together to form a Local Area Network.
- 22. Switch A Switch is an intelligent device that connects several nodes to form a network and redirects the received information only to intended node(s). A switch is an intelligent hub. It sends the information selectively only to those computers for which it is intended.
- 23. Repeater A Repeater is a device that is used to regenerate a signal which is on its way through a communication channel. A repeater regenerates the received signal and re-transmits it to its destination.
- 24. Router Routers are networking devices that forward data packets from the source machine to the destination machine using the shortest path. Routers work on IP addresses for connecting two or more LANs orWANs using routing table.
- 25. Cloud Computing Cloud Computing is a type of internet-based computing that provides shared computer processing resources and data to computers and other devices on demand. It allows storing, accessing data and programs using the internet.
- 26. Network Security The digital world is changing at a tremendous pace. New communication technologies open up new possibilities, but by using them you also expose yourself, and others to various risks. So, here are few methods to protect yourself from these threats.
- 27. Strong Password By assigning strong passwords to the users of a system, it can be ensured that only authorized people access a computer.This helps in increasing the computer as well as network security. A weak password can be cracked in a few attempts.
- 28. Firewall A firewall is a hardware device or a software that is installed to monitor the data entering the computer or leaving it. A firewall permits only that data to enter or leave a computer for which permissions have been granted by the computer.