L&T i.e. Larsen & Toubro named on its founder Henning Holck Larsen and Soren Kristain Toubro.L&T is a technology, engineering, constructions and manufacturing company.Basically it consist of many independent domains such as Power, Hydrocarbon, InfoTech etc.
More than one computer interconnected through a communication medium for information interchange is called a computer network. A network consists computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications.The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
Networking cables are used to connect one network device to other or to connect two or more computers to share printer, scanner etc. Different types of network cables are:1. TWISTED PAIR2. COAXIAL CABLE3. OPTICAL FIBER CABLE4. CROSSOVER CABLES
STRAIGHT-THROUGH & CROSSOVER CABLES Straight-through cables are used to connect different types of Ethernet equipment—like the connections running from a computer‘s network interface card to a hub or a switch. Crossover cables patch between similar types of equipment having similar interfaces, like two PCs in a network.
The technology which uses the radio waves to transmit or receive data is called as Wireless Technology. Radio technology is at the base of all wireless communication, cell phones, in radio broadcasting or in remote controls. Sending and receiving radio waves Communication through radio waves is achieved by having a sender that generates the radio waves and a receiver that picks up the radio waves. In wireless networks, devices like laptops, pc’s and smart phones can both send and receive radio signals in order to communicate with each other or with an access point.
LAN (Local Area Network) MAN (Metropolitan Area Network) WAN (Wide Area Network)
802.11 – Only supported a maximum network bandwidth of 2 Mbps – Too slow for most applications. For this reason, ordinary 802.11 wireless products are no longer manufactured. 802.11b – 802.11b supports bandwidth up to 11 Mbps and uses the same radio signaling frequency (2.4 GHz) as the original 802.11 standard.
802.11a – 802.11a supports bandwidth up to 54 Mbps and signals in a frequency spectrum around 5 GHz. – Have more difficulty penetrating walls and other obstructions. 802.11g – 802.11g attempts to combine the best of both 802.11a and 802.11b. 802.11g supports bandwidth up to 54 Mbps, and it uses the 2.4 Ghz frequency for greater range. 802.11n – When this standard is finalized, 802.11n connections should support data rates of over 100 Mbps. 802.11n also offers somewhat better range over earlier Wi-Fi standards due to its increased signal intensity.
The OSI (Open System Interconnection) model describes how information makes its way from application programs through a network medium to another application program in other computer. It divides one big problem in to seven smaller problems. Each problem is addressed by one of the seven layers of the OSI model.
Application LayerPresentation LayerSession LayerTransport LayerNetwork LayerData Link LayerPhysical Layer
Communication Media:• Communication media is used to transfer data from one computer to another computer.• For e.g. twisted pair, optical fibre, wireless, etc. NIC:• NIC stands for network interface card.• It is a device that physically connects each computer to a network.• It controls the flow of information between the network and the computer.
Router• A router is a device that connects multiple networks using similar or different protocols.• It manages the best route between two communication networks.Gateway• The link between two computers to connect to internet or another network is called gateway.• Gateways are generally designed and used for LAN- WAN connections and not for inter LAN communications.• A network gateway work like a firewall and filters packets.
Hubs• Hubs are capable of joining more than two PC but having some demerits like if two PC would want to communicate at a time then there would be a collision and the both PC would have to send the data once again.Switch• This shortcoming of Hub is overcome by Switches.• Switches are intelligent devices which work on the Layer2 of the OSI model.• It builds a MAC address table. So when a frame is received, it knows exactly which port to send it to.
In general, all of the machines on the Internet can be categorized as two types: servers and clients. Those machines that provide services (like Web servers or FTP servers) to other machines are servers. The machines that are used to connect to those services are clients.
A protocol is the special set of rules that end points in a telecommunication connection use when they communicate. Protocols specify interactions between the communicating entities.Protocols exist at several levels in a telecommuni- cation connection.In Open Systems Interconnection (OSI), there are one or more protocols at each layer in the telecommunication exchange
Every machine on the internet has a unique identifying number, called an IP Address.A typical IP ADDRESS is a 32-bit number, usually written in dotted decimal form that uniquely identifies a computer.Each IP address is split into 2 sections: 1) Network address 2) Host addressFor e.g.: 127.0.0.1
IPv4 Address Classes The IPv4 address space can be subdivided into 5 classes - Class A, B, C, D and E. Each class consists of a contiguous subset of the overall IPv4 address range. Class Leftmost bits Start address Finish address A 0xxx 0.0.0.0 127.255.255.255 B 10xx 126.96.36.199 188.8.131.52 C 110x 192.0.0.0 184.108.40.206 D 1110 220.127.116.11 18.104.22.168 E 1111 240.0.0.0 255.255.255.255
A server is a physical computer dedicated to running one or more services (as a host), to serve the needs of users of the other computers on the network. Depending on the computing service that it offers it could be a database server, file server, mail server, print server, web server, gaming server, or some other kind of server. The two types of servers are: 1. Rack-mount server 2. Blade server
• A rack-mounted server, is a computer dedicated server and designed to be installed in a framework called a rack.• A single rack can contain multiple servers stacked one above the other.• The rack server configuration also simplifies cabling among network components.
• A blade server is a server chassis housing multiple thin, modular electronic circuit boards, known as server blades.• The blades contain processors, memory, integrated network controllers and other input/output (IO) ports.• Each blade in a server is dedicated to a single application.