Introduction to network

A computer network is a network of two or more interconnected computers that are linked together to provide sharing of information, resources (hardware sharing), and enhanced communication. Each device on a network is called a host, and a connection between two hosts is known as Link.

A computer network can be of three or four personal computers in an office group, or a global collection of networks including thousands of personal computers, mainframes computers, minicomputers, and other devices.

Components of computer network

Client/Node- Client/Node is the normal computer system which is connected to network for sharing of resources.

Server- Server is a computer that handles request for data, email, files and other network services from other computers(clients/nodes)

Network interface card (NIC)- NIC is a device inside a computer or network device that enables communication with a network.

Modem- A modem is a hardware device that allows a computer to send and receive information over telephone lines. When sending a signal, the device converts (modulates) digital data to an analog signal, and transmits it over a telephone line. Similarly, when an analog signal is received, the modem converts it back (demodulates) to a digital signal.

Network HUB- A network HUB is designed to connect computers. When a hub receives packets of data from a connected device, it broadcasts that data packets to all other connected devices. Additionally, network bandwidth split between all of the connected computers, which causes slower connection speed.

Network switch- A network switch also connects computers to each other, like a hub. But its packets handling function is different from a hub. When a switch receives a packet of data, it determines what computer or device the packet is intended for and sends it to that computer or device only. Additionally, there is no network bandwidth split between all of the connected computers. So we can get good connection speed.

Network router- A router connects devices within a network by forwarding data packets between them. This data can be sent between devices, or from devices to the internet. The router does this by assigning a local IP address to each of the devices on the network.

Advantages and Disadvantages of computer network

Advantages

Sharing devices such as printers saves money.
Software licences are likely to be cheaper because of software sharing between several computers.
Files can easily be shared between users.
Network users can communicate by email and instant messenger.
Security is good - users cannot see other user's files without their consent.
Easy data backup is possible because all the data is stored on the file server.

Disadvantages

Purchasing the network cabling and file servers can be expensive.
Managing a large network is complicated, requires training, and a network manager usually needs to be employed.
Viruses can spread to other computers throughout a computer network.
There is a danger of hacking.

UNIT-102

Network and Internet Concepts