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A network (Computer Networks) is a telecommunication network that allows computers to exchange data. Physical connection is established between computers either by cable or wireless infrastructure

Introduction :

a) The purpose of a network is to enable the sharing of files and information between multiple systems.
b) A network is a series of nodes interconnected with communication device to enable interconnection between computers.
c) Computer networks can be connected through cables, such as Ethernet cables or phone lines, or wirelessly, using wireless networking cards that send and receive data through the air.
d) There are various different kind of topologies and they are likely Bus, Star, Token ring and Mesh.
e) Network also enables the user to share resources such as Printers, Plotters, etc.,

Architecture :

LAN Architecture :

Features :

Since network is used for interconnection of systems to share resources, it has various features and they are:
• Resource sharing
• Increased storage capacity
• Increased cost efficiency
• Time consuming
• Security
• Centralized management
• Less Expensive
• Convenient for user monitoring
• Interaction between users

Hardware Components :

• Network Interfaces
• Repeaters and Hubs
• Bridges
• Switches and Routers
• Firewalls

Real Time Examples :

There is a pool of real-time applications of the networks.
• LAN connections in Offices, Colleges, Schools
• Internet connection across the world
• Communication through internet (Emails)
• Resource sharing
• Streaming video and audio via internet
• Sharing files and information.

Network Security

Network Security consists of the provisions and policies adopted by a network administrator to prevent and monitor unauthorized access, misuse, notifications or a denial of a computer network and its resources. It also includes the authorizations of access to data in a network.

Introduction :

a) It is generally enforced by assigning a User ID and Password for the users and potential users ought to register themselves for the same.
b) It not only protects the network but also oversees operation being done.
c) It can also be said as a special field in computer networking that cares about the computer network and its infrastructure.
d) It is modelled to protect the usability, reliability, integrity and safety of the network and data.
e) A well modelled network security scheme targets a variety of threats and potential threats. It stops them from entering the network.
f) It is generally handled by the network administrator.

Block Diagrams:


The very familiar and most common network security threats include
• Viruses, worms and Trojans
• Spyware, Adware
• Zero-hour attacks
• Hacker attacks
• Denial of service attacks
• Data interception theft
• Identity theft


• Antivirus or Antispyware
• Firewall
• Intrusion Prevention System


There are several types of attacks that are currently used by the intruders / attackers / hackers to breach the security in networks.
• Active attack
• Passive attack
• Distributed attack
• Insider attack
• Close-in attack
• Phishing attack
• Hijack attack
• Spoof attack
• Buffer overflow
• Exploit attack
• Password attack

Real time Examples

• Authentication Applications
• IP Security
• Email Security
• Anti Virus Protection
• Browser Security (Secure browsing)
• Web security Standards
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