Current Affairs PDF

Data Communication and Network

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Data communications refers to the transmission of digital data between two or more computers and a computer network. The physical connection between networked computing devices is established using either cable media or wireless media. The best-known computer network is the Internet.

The transmission of data is carried out by the propagation and processing of signals. The different types of transmission are,

  • Parallel Data Transmission – The sender sends all the bits at once on all lines. Because data lines are equal to the number of bits in a group or data frame. Advantage of Parallel transmission is speed and disadvantage is the cost of wires, as it is equal to the number of bits needs to send parallelly.
  • Serial Data Transmission –  Bits are sent one after another in a queue manner. It is slower than the Parallel Data Transmission.
  • Synchronous Data Transmission – Data-bits have specific pattern and helps receiver
    recognize when the actual data bits start and where it ends

Computer Network and it’s Types

The different types of Computer Networks are,

  • Personal Area Network
  • Local Area Network
  • Metropolitan Area Network
  • Wide Area Network
  • Storage Area Network
  • System Area Network
  • Controller Area Network

Personal Area Network (PAN)

PAN is the smallest network which is very personal. PAN network has a connectivity range of 10 meters. Bluetooth devices and Infra-Red devices are the common PAN devices. Bluetooth enabled Keyboard or Mouse, TV remote, wireless printers are some examples of PAN network.

Local Area Network (LAN)

LAN is a computer network spanned inside a building and operated under single administrative system. Each computer is connected by cables. LAN provides a useful way of sharing resources between end users. LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited. Resources like Printers, File Servers, Scanners and internet is easy sharable among computers.

Metropolitan Area Network (MAN)

A network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned an operated by a single entity such as a government body or large corporation.  MANs provide Internet connectivity for LANs in a metropolitan region, and connect them to WANs like the Internet.

Wide Area Network (WAN)

A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs). Generally, telecommunication networks are Wide Area Network. These networks provides connectivity to MANs and LANs. Equipped with very high speed backbone, WAN uses very expensive network equipment.They can also be connected through leased lines or satellites. The largest WAN in existence is the Internet.

Storage Area Network (SAN)

A Storage area network is a high-speed network of storage devices that also connects those storage devices with servers. SAN storage devices can include tape libraries, and, more commonly, disk-based devices.

System Area Network

System Area Network links high-performance computers with high-speed connections in a cluster configuration. Also known as Cluster Area Network.

Controller Area Network

Controller Area Network is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer.


Communication is carried out by means of

  • Modem –  a device that enables a computer to transmit data over telephone lines.
  • Optical Fiber – permit transmission over longer distances and at higher bandwidths.
  • Satellites – data can be transferred from one part of the world to any part of the world.
  • Twisted pair wire – used for telephone lines
  • Coaxial cable – a type of cable that is used by cable TV and that is common for data communications