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Networking concepts............ Computer network a computer network can be defined as a group of computers and other peripheral devices that are linked together for the purpose of sharing data and hardware resources. For example, if one of the computers in the network has a printer attached to it, then all the computers in that network can assess the printer and use it to print documents. As we can see in the picture given below here all the computers can give command to the printer. the computers in a network can communicate with each other as well as work independently. each computer in a network is called a NOD Advantages of networking Here are some advantages of networking Resources sharing - in a computer network all the hardware and software resources are shared among the users of the networks the additional peripheral devices such as printers, scanners, modems, fax machines and etc. Can be connected to 1 central computer and shared among the others. also, it becomes very easy and convenient to share the data and files among the users of a computer network. It also saves time Reduction of cost - The cost of hardware is considerably less in a computer network as all the computers share the hardware resources. the software costs can also be saved by purchasing the software and licenses for the server, and distributing them to the people. Increased storage capacity - in a network the user can store their files on the remote computers so they get more space to their data Fast data transfer - Networking provides a facility to transfer the soft copies from one computer to the other at a high speed. Easy to take backup - It is difficult maintain regular fair caps on a number of standalone computers. You can set the server to take regular backups on data automatically.

Disadvantages of networking Here are some disadvantages Additional cost of networking equipment - uh networks cost might get reduced by sharing the hardware resources however additional cost of establishing the network gets incurred. Management of large networking - maintaining a large computer network can be a challenging task. It requires expertise & special training Sever breakdown - if a server breaks down in the network, then all the computers become isolated security issues - a computer network is always at a risk of getting a tag by external threats, such as unauthorized use of resources, virus attacks, and alike. If the network is not secured, then the data of the organization may be at a high risk. Networking components to establish wired networking in a group of computers you require some additional components that are as follows Network card - network card is used to physically attach a computer to a network, so that it can participate in network communication Ethernet Network Card is the most commonly used network card. Networking cable - modern Ethernet networks used twisted pair cable, containing eight wires these wires are arranged in a special order & an RJ-45 connector Modem – A modem enables you to connect your computer to the available internet connection over the existing telephone lines. Hub – a hub is a network device that is used to connect all the computer in a network with each other. When a computer sends a request in a network it is first sent to the hub by the cable the hub then transmits that request to all the other computers in that network, which checks whether the message belongs to them or not if not then that message is dropped this process is called BROADCASTING

Switch – a switch is almost like a hub. but a switch dose not BROADCAST the message of an entire network. It transmits the message from the source computer to the destination computer only by using the physical adders. This way direct connection can happen. Router – a router connects 2 different types of networks with each other for e.g. LAN with WAN Wireless networking Wireless network cards are used instead of the normal network cards that are used in wired networks. Most laptops, computers come with the inbuilt wireless network cards. Radio signals are used for transferring data, therefore the ethernet cable is not required Access points or routers have a wireless antenna, which increases the communication range of the radio signals. They can also be used to join wired networks, thus making the network a combination of wired as well as wireless networks Types of networks There are 6 types of networks PAN (personal area network) LAN (local area network) MAN (metropolitan area network) WAN (wide area network) PAN (personal area network) is a computer network that is mainly created for an individual person. It is used for communication among devices, such as laptops, mobile phones personal digital assistants (PDAs) or smartphones personal area networks can either be wired or wireless. It generally covers a range of less than 10 meters that is about 30 feet. We can also use these networks to transfer files for e.g. – mails photos & music. LAN (local area network) when 2 or more computers & peripheral devices are connected within a small area such as a room or a campus. In LAN computers terminals are physically connected with wires. the data transmission speed in LAN is very fast. Since it is operated in a small area it can be controlled & administered by a single person or an organization MAN (metropolitan area network) MAN is a large network then LAN and spreads almost across a city. Since it covers an entire city, it is called metropolitan. The most common example of MAN is the city cable network or branches of a local bank in a city WAN (wide area network) this kind of network connects 2 or more computers located at a distant place. They are linked by communication facilities like telecommunication or satellite

signals. The main characteristic of WAN is that is requires a public telecommunication media to transfer data one common e.g., of WAN are ATMs Network architecture Network architecture is an overall design of a computer network that describes how a computer network is configured and what strategies are being used in it. It is mainly in 2 types Client – server network Peer-to-peer network Client – server network In a client server network, several computer's called clients or workstations are connected to the main computer called the server. A sever is a computer that provides services to clients and controls access to hardware software, and other resources. Clients are the computers that request services, like data retrieval, storage and etc. from the server ax Peer-to-peer network A peer-to-peer network is the one where a few computers of equal capacity and capabilities are connected together to use the resources available on the network. In a peer-to-peer network there is no central server instead each computer can act both as a server as well as a client Network topologies The network topology is the arrangement of nodes and links in a particular mechanism and scheme. In other words, the network topology is how the network components that make the communication between the devices in a network would be arranged to reduce errors, produce more bandwidth speed, secure the network, etc. Point-to-point Point-to-point topology is the simplest form of network structure in which 2 nodes are directly connected with each other. This type of network is more s suitable for small areas where computers are close proximity. This technology provides a faster & reliable connection

Bus topology This topology uses a single communication line or 1 main cable to which all nodes are directly connected the main cable acts as a backbone for the network. It transmits data only in one direction. In this type of structure, one on of the computers in the network acts as the computer sever, that provides data to all clients. This topology is used in small networks where cable requirement is relatively small. One of the disadvantages of such type of network is that if the main cable fails , the entire network becomes unusable . Star topology In Star Topology each device is connected to central computer using a point to point connection. The central server act as a Hub. Devices communicate across the b=network by passing data through this hub. Star Topology is very popular because the start up cost is low. It is easy to add a New device to the network as only once cable is required and the congregation is simple. Moreover, the network is robust. Even if a Connection in a network fails, the other connection remain in tact. If the central hub fails, the entire network goes Down. Ring Topology In the ring topology all the nodes in the network are connected in a circular manner. Each node connects with exactly to other nodes. Forming a single continue pathway for signals. When one node sends message to the other node it is not adjacent to it, the data travel to all the intimidate nodes. Until it reaches its final destination. Ring topology are used in both LAN and WAN Setup. The main disadvantage of this topology is that if one work station goes down the entire network gets effected. Since the Data being Transferred over the network has to pass through each workstation This makes its slower than the Start Topology. Tree Topology Tree Topology is one of the most common network setup that consist of group of star figure workstation connected to work Linear bus back bone cable. In this one star network is connected to the other start network. In a Tree network a cable failure in one of the star

network will effect only the workstation that is linked to the central computer of that star network. All the other workstation will continue to function normally. However if a central computer goes down the entire workstation connected to it will suffer either degraded performance or complete failure. Though the expansion of the network is possible and easy but maintaining becomes difficult. Mesh Topology mesh network topology Eash node is connected to every other node in the network in this topology every node not only sends its own signals but also relays data from the other nodes this type of topology can handle a large volume of data traffic it is commonly used in wireless networks. s Network security Network security means protecting data and resources from any unauthorized access it is the most important aspect in computer networking. Since many user are accessing the same data it is essential that the steps the taken to ensure it proper security. The right to access or modify any data should be given only to the authorized people consider the following points that may happen in any organization. Some employee may try to change the data considering there leave records Salary Performance appraisals etc. Accidental deletion of important data may happen. Former employee or some other people may try to harm the company's data. People outside the company may try to access the confidential data. The re are two general levels of Network Security. These are the following. Login Security A user is given a Unique login name and password. Right Security: Based upon the username, the user is given rights like Read only access or read write access or no access at all.