Chapter – 11 Class 12 CS – Sumita Arora Assignment | Q/A

A network is connection of two or more computers through a communication line(cables, wire, wireless) in purpose to share information and resources. For example : if multiple computers are connected through a printer than each computer can access the printer.

Goals

1. Resource sharing make sure the availability of the to each node.
2. High reliability ensures alternate source of supply.
3. Saving money is the another advantage of the network.
4. It also leads the increase in the performance and efficiency of system.

Applications:

Access of the data to remote programs.
Access to remote databases everywhere.
Value-added communication facilities and enhancement.

A network can refer from a few numbers of system to a few hundred number of system that depends on type of network.

Types of networks:

• LAN (local area network)
  • It is privately-owned networks within a single building or campus of up to a few kilometres in size.
  • This is first preference for the personal and workstation network to share resources and hardware.
  • In these cables are used as medium at speeds of 10 Mbps to 100 Mbps.
  • This is restricted is size.
• MAN (metropolitan area networks)
  • It generally refers to the network in a city.
  • In this the main content is data shearing over all range.
  • In this a cable network is spread over a city area.
• WAN (wide area network)
  • It generally refers to the spans of a large geographical area, often a country or continent.
  • In this the connection network offers a public connection such as telephone network.
• PAN (personal area network)
  • This is interconnection of information through a personal network of range of 10 metres.
  • For example a connection of personal mobile phone, tablet and portable devices like printer etc. over single communication line.

A hub is a hardware device that used to connect several network together to a single chain. Hubs are devices commonly used to connect segments of a LAN. Such as when a packet arrives at one port, the hub copy to the other ports so that all segments of the LAN can see all packets.

Types of Hubs:

• Active hubs electrically amplify the signal as it moves from the one connected part to another. These somehow works like repeaters.
• Passive hubs just pass the signal from one connected part to other without any changes.

A switch is a hardware device that is used to segment the networks into different subnetwork called subnets or LAN segments.

It is a better approach to avoid traffic over a single network and also help in filtering the backward and forward packet transmission.

Bridge is a device that connects and passes packets between two network segments that use the same communications’ protocol.
In this bridge know which side having which system and hence communicate according to that.

Router: It acts similar like bridge that act as communicator within segments of network. It enhances and improve the reliability of network.
It can also handle multiple protocol advanced over the bridge.

Gateway: It is a hardware device that connects dissimilar networks to form a single channel.
It establishes an intelligent network between the LAN and external network.

(i) We would prefer bridges over hubs when we need to connect multiple networks to single active one.

(ii) We would prefer switch over others network devices when we want to segment networks into different subnetworks to prevent traffic overloading.

We would opt for a router in a network when we want to connect different network of different protocol.
For example, a router can link Ethernet to a mainframe.

A hub is a hardware device that used to connect several network together to a single chain. Hubs are devices commonly used to connect segments of a LAN. Such as when a packet arrives at one port, the hub copy to the other ports so that all segments of the LAN can see all packets.

Active hubs electrically amplify the signal as it moves from the one connected part to another whereas Passive hubs just pass the signal from one connected part to other without any changes.

A server is a computer used in a network and which provides a service to a client. 
Servers usually have more processing power, memory and storage than client computers. It provides a central unit for storages and commanding unit.

In a peer-to-peer network, there are no dedicated servers and there is no any such hierarchy.
In this network there is no client and the server relationship exist.

Cloud computing is Internet-based computing, whereby shared resources, software and information are provided to computers and other device on demand.
This computing is delivered through a network usually the internet.

Different cloud deployment models are:

• Private Cloud are basically handled by single organization and typically controlled by a private data centre. It is exclusive for use of organization.
• Public Cloud used by multiple organization on a shared basis and hosted by third party provider.
• Community Cloud used by group of related organization who wish to make use of a common cloud computing environment.
• Hybrid Cloud is adopted by organization to use both public and private cloud in order to have advantage of both cloud types.

• Private Cloud are basically handled by single organization and typically controlled by a private data centre.
  It is exclusive for use of organization.
  In this access restricted to the hosting organization only.
  
• Public Cloud used by multiple organization on a shared basis and hosted by third party provider.
  This is for the open access but with some improvisation.
  

The Internet of Things (IoT) is a network of ‘smart’ devices that connect and communicate via the Internet.
The key to the IoT is the interconnectivity of devices, which collect and exchange information through embedded software, cameras and sensors.

IoT is enabled by several technologies

• Wireless sensor networks
• Cloud computing,
• Big data analytics,
• Embedded Systems
• Mobile Internet etc.

• Privacy
• Hardware issues
• Encryption of data
• Less network awareness
• Insecure software