unit 1 iwt internet and web technology rgpv syllabus

internet and web technology

1. Unit 1 Introduction

2. Introduction A computer network is a system in which multiple computers are connected to each other to share information and resources. Characteristics of a Computer Network • Share resources from one computer to another. • Create files and store them in one computer, access those files from the other computer(s) connected over the network. • Connect a printer, scanner, or a fax machine to one computer within the network and let other computers of the network use the machines available over the network.

3. GOALS OF NETWORKING • Resource and load sharing • Programs do not need to run on a single machine • Reduced cost • Several machines can share printers, tape drives, etc. • High reliability • If a machine goes down, another can take over • Mail and communication

4. Application of Computer network Marketing and sales Manufacturing Financial services Cable television Electonic messaging Cellular telephone Information services

5. Topolology Topology defines the structure of the network of how all the components are interconnected to each other. There are two types of topology: physical and logical topology

6. MESH Mesh technology is an arrangement of the network in which computers are interconnected with each other through various redundant connections. There are multiple paths from one computer to another computer. It does not contain the switch, hub or any central computer which acts as a central point of communication. The Internet is an example of the mesh topology. Mesh topology is mainly used for WAN implementations where communication failures are a critical concern. Mesh topology is mainly used for wireless networks. Mesh topology can be formed by using the formula: Number of cables = (n*(n-1))/2; Where n is the number of nodes that represents the network.

7. : Advantages of Mesh topology Reliable:  The mesh topology networks are very reliable as if any link breakdown will not affect the communication between connected computers. Fast Communication:  Communication is very fast between the nodes. Disadvantages of Mesh topology Cost:  A mesh topology contains a large number of connected devices such as a router and more transmission media than other topologies. Management:  Mesh topology networks are very large and very difficult to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected.

8. Star Star topology is an arrangement of the network in which every node is connected to the central hub, switch or a central computer. The central computer is known as a  server , and the peripheral devices attached to the server are known as  clients . Coaxial cable or RJ-45 cables are used to connect the computers. Hubs or Switches are mainly used as connection devices in a  physical star topology . Star topology is the most popular topology in network implementation.

9. Advantages of Star topology Network control:  Complex network control features can be easily implemented in the star topology. Any changes made in the star topology are automatically accommodated. Limited failure:  As each station is connected to the central hub with its own cable, therefore failure in one cable will not affect the entire network. Familiar technology:  Star topology is a familiar technology as its tools are cost-effective. Easily expandable:  It is easily expandable as new stations can be added to the open ports on the hub. Cost effective:  Star topology networks are cost-effective as it uses inexpensive coaxial cable. High data speeds:  It supports a bandwidth of approx 100Mbps. Ethernet 100BaseT is one of the most popular Star topology networks.

10. Disadvantages of Star topology A Central point of failure:  If the central hub or switch goes down, then all the connected nodes will not be able to communicate with each other. Cable:  Sometimes cable routing becomes difficult when a significant amount of routing is required.

11. Tree topology Tree topology combines the characteristics of bus topology and star topology. A tree topology is a type of structure in which all the computers are connected with each other in hierarchical fashion. The top-most node in tree topology is known as a root node, and all other nodes are the descendants of the root node. There is only one path exists between two nodes for the data transmission. Thus, it forms a parent-child hierarchy.

12. Bus Topology The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone cable. Each node is either connected to the backbone cable by drop cable or directly connected to the backbone cable. When a node wants to send a message over the network, it puts a message over the network. All the stations available in the network will receive the message whether it has been addressed or not. The bus topology is mainly used in 802.3 (ethernet) and 802.4 standard networks. The configuration of a bus topology is quite simpler as compared to other topologies. The backbone cable is considered as a  "single lane"  through which the message is broadcast to all the stations. The most common access method of the bus topologies is  CSMA  (Carrier Sense Multiple Access).

13. Advantages of Bus topology: Low-cost cable:  In bus topology, nodes are directly connected to the cable without passing through a hub. Therefore, the initial cost of installation is low. Moderate data speeds:  Coaxial or twisted pair cables are mainly used in bus-based networks that support upto 10 Mbps. Familiar technology:  Bus topology is a familiar technology as the installation and troubleshooting techniques are well known, and hardware components are easily available. Limited failure:  A failure in one node will not have any effect on other nodes.

14. Disadvantages of Bus topology: Extensive cabling:  A bus topology is quite simpler, but still it requires a lot of cabling. Difficult troubleshooting:  It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes. Signal interference:  If two nodes send the messages simultaneously, then the signals of both the nodes collide with each other. Reconfiguration difficult:  Adding new devices to the network would slow down the network. Attenuation:  Attenuation is a loss of signal leads to communication issues. Repeaters are used to regenerate the signal.

15. Ring Topology Ring topology is like a bus topology, but with connected ends. The node that receives the message from the previous computer will retransmit to the next node. The data flows in one direction, i.e., it is unidirectional. The data flows in a single loop continuously known as an endless loop. It has no terminated ends, i.e., each node is connected to other node and having no termination point. The data in a ring topology flow in a clockwise direction. The most common access method of the ring topology is  token passing . Token passing:  It is a network access method in which token is passed from one node to another node. Token:  It is a frame that circulates around the network.

16. OSI Model The OSI Model is a theoretical, seven-layered model of how networks work. The Open Systems Interconnect Model (the OSI Model) is a theoretical model of networking that organizes network functions into seven layers (physical layer, datalink layer, network layer, transport layer, session layer, presentation layer and application layer)

17. What is Internet? Internet is a network of computers linking many different types of computers all over the world. It is a network of networks sharing a common mechanism for addressing(identifying) computers, and a common set of communication protocols for communications between two computers on the network.

18. Applications of Internet 1. Communication Computer users around the world extensively use the email service on internet to communicate with each other. Pictures, documents and other files are sent as email attachments. Emails can be cc-ed to multiple email addresses 2. Job search Nowadays, many people search for their jobs online as it is quicker and there is a larger variety of job vacancies present. People can publish resume online for prospective job 3. Online Shopping The internet has also facilitated the introduction of a new market concept consisting of virtual shops. They provide information about products or services for sale through www servers. 4. Stock market updates You can sell or buy shares while sitting on computer through internet. Several websites like ndtvprofit.com, moneypore.com, provide information regarding investment

19. Applications of Internet 5. Travel One can use internet to gather information about various tourist place. it can be used for booking Holiday tours, hotels, train, bus, flights and cabs. 6. Research Research papers are present online which helps in the researcher doing literature review. 7. E-Commerce E–commerce (electronic commerce or EC) is the buying and selling of goods and services, or the transmitting of funds or data, over an electronic network, primarily the Internet. 8. Social networking Social networking is the use of internet-based social media programs to make connections with friends, family, classmates, customers and clients.

20. WWW (World wide Web) The World Wide Web has been central to the development of the Information Age and is the primary tool billions of people use to interact on the Internet. Web pages are primarily text documents formatted and annotated with Hypertext Markup Language (HTML). In addition to formatted text, web pages may contain images, video, audio, and software components that are rendered in the user's web browser as coherent pages of multimedia content. Embedded hyperlinks permit users to navigate between web pages. Multiple web pages with a common theme, a common domain name, or both, make up a website.

21. The terms Internet and World Wide Web are often used in every-day speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a global system of interconnected computer networks. In contrast, the Web is one of the services that runs on the Internet. It is a collection of interconnected documents and other resources, linked by hyperlinks and URLs. In short, the Web is an application running on the Internet. Viewing a web page on the World Wide Web normally begins either by typing the URL of the page into a web browser, or by following a hyperlink to that page or resource. The web browser then initiates a series of communication messages, behind the scenes, in order to fetch and display

22. basic components: The Web Server: a computer and software ("server" can refer to either) that stores and distributes data to other computers throughout the Internet that request the information. The Web Browser: software running on an individual's ("client") computer that request information from the Web server and displays it in a manner of directed in the data file itself.

23. Introduction to E-Commerce The term "Electronic commerce" (or e-Commerce) refers to the use of an electronic medium to carry out commercial transactions. Most of the time, it refers to the sale of products via Internet, but the term eCommerce also covers purchasing mechanisms via Internet (for B-To-B). A client who purchases on the Internet is called a cyber consumer. E-Commerce is not only limited to online sales,but also covers many things

24. INTERNETWORKING Internetworking is the process or technique of connecting different networks by using intermediary devices such as routers or gateway devices. Internetworking started as a way to connect disparate types of computer networking technology. Computer network term is used to describe two or more computers that are linked to each other. When two or more computer networks or computer network segments are connected using devices such as a router then it is called as computer internetworking.

25. There are three variants of internetwork or Internetworking, depending on who administers and who participates in them: ∙ Extranet ∙ Intranet ∙ Internet

26. Extranet An extranet is a network of internetwork or Internetworking that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities. Internet consisting of a worldwide interconnection of governmental, academic, public, and private networks based upon the Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense also home to the World Wide Web (WWW) and referred to as the 'Internet' with a capital 'I' to distinguish it from other generic internetworks. Intranet an intranet is the internal network of a company or other enterprise. A large intranet will typically have its own web server to provide users with browsable information.

27. Different type of networking devices:

28. internetworking device An internetworking device is a widely-used term for any hardware within networks that connect different network resources. Key devices that comprise a network are routers, bridges, repeaters and gateways.

29. Network Hub: Network Hub is a networking device which is used to connect multiple network hosts. A network hub is also used to do data transfer. The data is transferred in terms of packets on a computer network. So when a host sends a data packet to a network hub, the hub copies the data packet to all of its ports connected to. Like this, all the ports know about the data and the port for whom the packet is intended, claims the packet.

30. Repeaters Repeaters are used to extend the length of the Network. Repeaters were created to regenerate and amplify weak signals, thus extending the length of the network. The basic function of a repeater is toretime,reshape,andreamplifythedatasignaltoitsoriginallevel.

31. Bridges The device that can be used to interconnect two separate LANs is known as a bridge. It is commonly used to connect two similar or dissimilar LANs as shown in Fig.1.3. The bridge operates in layer 2, that is data-link layer and that is why it is called level-2 relay with reference to the OSI model.

32. Switches Like a hub, a switch also works at the layer of LAN (Local Area Network) but you can say that a switch is more intelligent than a hub. A network switch connects devices in a network to each other, enabling them to talk by exchanging data packets. Switches can be hardware devices that manage physical networks or software-based virtual devices. A network switch operates on the data-link layer, or Layer 2, of the Open Systems Interconnection (OSI) model.

33. modem A modem stands for (Modulator+Demodulator). That means it modulates and demodulates the signal between the digital data of a computer and the analogue signal of a telephone line. This wire is used to carry our internet data outside to the internet world. However, our computer generates binary data or digital data

34. Router Routers link two or more different networks together, such as an Internet Protocol network.A router receives packets and selects the optimum path to forward the packet across the network. Routers build a table of all the device addresses(routing table)across the networks. Using this table, the router forwards a transmission from the sending station to the receiving station across the best path.Routers operate at the network level of the OSI model.

35. Gateways Gateways are multi-purpose connection devices. They are able to convert the format of data in one computing environment to a format that is usable in another computer environment(for example,AppleTalk and DECnet). gateway is a device which forms a link between them. It allows the computer programs, either on the same computer or on different computers to share information across the network through protocols. A router is also a gateway, since it interprets data from one network protocol to another.

36. Network cards Network cards also known as Network Interface Cards (NICs) are hardware devices that connect a computer with the network. They are installed on the motherboard. They are responsible for developing a physical connection between the network and the computer. Computer data is translated into electrical signals send to the network via Network Interface

37. Hyper Text Transfer Protocol (HTTP) Hyper Text Transfer Protocol (HTTP) allows transfer from one document to another using this hyper text by clicking a link you can go to some other place. There should be a mechanism in built in the http protocol which should support this kind of a thing.the http server runs over port number 80 but some web servers also run over some other port number like 8080 or something else also. So you must know the port number on which the server is running. So that you can establish a connection to it typically by default the port number is 80.

38. the http request format a client request to the server consists of a request method there are several request methods we shall be talking about get head POST port etc HTTPS URLs begin with "https://" and use port 443 by default, whereas HTTP URLs begin with "http://" and use port 80 by default.

39. Hypertext Transfer Protocol Secure (HTTPS) Hypertext Transfer Protocol Secure (HTTPS) is a communications protocol for secure communication over a computer network, with especially wide deployment on the Internet. Technically, it is not a protocol in and of itself; rather, it is the result of simply layering the Hypertext Transfer Protocol (HTTP) on top of the SSL/TLS protocol, thus adding the security capabilities of SSL/TLS to standard HTTP communications. The main motivation for HTTPS is to prevent wiretapping and man-in-the-middle attacks.