Tuesday, 1 December 2015

Computer Networks (Basics) for IBPS IT Officers Exam

Dear readers, If you want to chat with your friend, or want to share your printer with your friend's system. Then you should connect your computer to his/her computer. In simple words, you are just forming a NETWORK by connecting two or more computers. These connections or arrangements are called Computer Networks.  These computers in the Computer Network may attached with cables, telephone lines, radio waves, satellites or infrared light beams.

There are two aspects in computer networks.
  • Hard Ware : It includes physical connection (using adapter, cable, router, bridge etc)
  • Soft Ware : It includes set of protocols (nothing but a set of rules) 
Basic types of Computer Networks :
Local Area Networks (LANs) :
These are the simple networks. A set of computers (2 or more) connected within a single building or college campus ( a few kilometres range)
Metropolitan Area Networks(MANs) :
These are the larger networks than LANs, these are limited to city or group of Nearby Offices. Simply we can say that a group of LANs are called a MAN (but guys, this is not a standard definition, its jst for your understanding purpose).
Wide Area Networks (WANs) : 
These type of networks provides long distance transmission of data and voice. (A city, state , country and ofcourse the world). it contains HOST and collection of machines. 
Now lets have a look at some basic differences between these three...
  • Area :
    • LAN : Covers small area.
    • WAN : Covers large geographical area
    • MAN : Covers larger than LAN but smaller than WAN
  • Error Rates :
    • LAN : Lowest
    • WAN : Highest
    • MAN : Moderate
  • Transmission speed :
    • LAN : High Speed
    • WAn : Low Speed
    • MAN : Moderate speed
  • Cost : 
    • LAN : Uses inexpensive equipment (i mean, if you have two systems, its hardly costs nothing (almost) to connect them with each other)
    • WAN : Uses most expensive equipment (Connecting systems via internet)
    • MAN : Uses moderately expensive equipment ( Connecting two systems in different buildings)
Till now we have discussed about the types of Networks. Now we shall discuss about HOW should we connect them.
Network Topology : A network Topology is the method or process which tells us about how to connect the Systems.
There are several types of Topologies are there.

Assume that the above green dots are computers.
Line Topology : If we connect several computers in a line then it is called as the LINE TOPOLOGY

Treee Topology : If we connect several systems in a hierarchical order, then it is called as the TREE TOPOLOGY
Bus Topology : If we connect several computers to a back bone (A wire) then it is called as the BUS TOPOLOGY.
Star Topology : If we connect several computers to a central hub (system) then it is called as the STAR TOPOLOGY.
Ring Topology : In line topology if we connected the last system to the starting system, then it is called as the Ring topology.
Mesh Topology : If we connect several systems with each other (There is no necessity that one system should connect with all the remaining systems in the network, see the diagram) then it is called as the Mesh Topology.
Fully Connected : In a Network if everysystem is connected with all the remaining systems then it is called as the Fully Connected topology.

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