2. 6/28/2016 2 A global mesh of interconnected networks (internetworks) meets these human communication needs. Some of these interconnected networks are owned by large public and private organizations, such as government agencies or industrial enterprises, and are reserved for their exclusive use. The most well-known and widely used publicly-accessible internetwork is the Internet. The Internet is created by the interconnection of networks belonging to Internet Service Providers (ISPs). These ISP networks connect to each other to provide access for millions of users all over the world. Ensuring effective communication across this diverse infrastructure requires the application of consistent and commonly recognized technologies and protocols as well as the cooperation of many network administration agencies.

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5. Meaning of URL – “Uniform Resource Locator”, is a string of characters used to represent and identify a page of information on the World Wide Web that is used by an web browser such as google,yahoo or Internet Explorer to find HTTP, FTP, telnet and other resources on the Internet. 6/28/2016 5

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7. 7 For devices to successfully communicate, a network protocol suite must describe precise requirements and interactions. Networking protocol suites describe processes such as:  The format or structure of the message  The method by which networking devices share information about pathways with other networks  How and when error and system messages are passed between devices  The setup and termination of data transfer sessions.. For example to common protocols (http,TCP,IP...)

8. What is server ?  In information technology, a server is a computer program that provides services to other computer programs (and their users) in the same or other computers.  The computer that a server program runs in is also frequently referred to as a server. 6/28/2016 8

9.  Hypertext Transfer Protocol (HTTP) is a common protocol that governs the way that a web server and a web client interact. HTTP defines the content and formatting of the requests and responses exchanged between the client and server. Both the client and the web server software implement HTTP as part of the application. The HTTP protocol relies on other protocols to govern how the messages are transported between client and server 6/28/2016 9

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11. 6/28/2016 11 A web search engine is designed to search for information on the World Wide Web. The search results are generally presented in a line of results often referred to as search engine results pages (SERPs). The information may be a specialist in web pages, images, information and other types of files. Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained only by human editors, search engines also maintain real-time information by running an algorithm on a web crawler.

12. 6/28/2016 12 is an organization that provides access to the Internet. Internet service providers can be either community-owned and non-profit, or privately owned and for-profit. Access ISPs directly connect clients to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and other people. Transit ISPs provide large amounts of bandwidth for connecting hosting ISPs to access ISPs.

13. 6/28/2016 13 A web hosting service is a type of Internet hosting service that allows individuals and organizations to make their website accessible via the World Wide Web. Web hosts are companies that provide space on a server owned or leased for use by clients, as well as providing Internet connectivity, typically in a data center. Web hosts can also provide data center space and connectivity to the Internet for other servers located in their data center, also known as Housing in Latin America or France

14. 6/28/2016 14 In the client/server model, the device requesting the information is called a client and the device responding to the request is called a server. Client and server processes are considered to be in the Application layer. The client begins the exchange by requesting data from the server, which responds by sending one or more streams of data to the client. Application layer protocols describe the format of the requests and responses between clients and servers. In addition to the actual data transfer, this exchange may also require control information, such as user authentication and the identification of a data file to be transferred.

15. 6/28/2016 15 Although data is typically described as flowing from the server to the client, some data always flows from the client to the server. Data flow may be equal in both directions, or may even be greater in the direction going from the client to the server. For example, a client may transfer a file to the server for storage purposes. Data transfer from a client to a server is referred to as an upload and data from a server to a client as a download.

16. 6/28/2016 16 The Open Systems Interconnection reference model is a layered, abstract representation created as a guideline for network protocol design. The OSI model divides the networking process into seven logical layers, each of which has unique functionality and to which are assigned specific services and protocols. In this model, information is passed from one layer to the next, starting at the Application layer on the transmitting host, proceeding down the hierarchy to the Physical layer, then passing over the communications channel to the destination host, where the information proceeds back up the hierarchy, ending at the Application layer. The figure depicts the steps in this process.

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18.  There are benefits to using a layered model to describe network protocols and operations. Using a layered model:  Assists in protocol design, because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below.  Fosters competition because products from different vendors can work together.  Prevents technology or capability changes in one layer from affecting other layers above and below.  Provides a common language to describe networking functions and capabilities. 6/28/2016 18

19. A high-level programming language that is interpreted by another program at runtime rather than compiled by the computer’s processor as other programming languages (such as C and C++) are. Scripting languages, which can be embedded within HTML, commonly are used to add functionality to a Web page, such as different menu styles or graphic displays or to serve dynamic advertisements. These types of languages are client-side scripting languages, affecting the data that the end user sees in a browser window. Other scripting languages are server-side scripting languages that manipulate the data, usually in a database, on the server. Scripting languages came about largely because of the development of the Internet as a communications tool. JavaScript, ASP, JSP, PHP, Perl, Tcl and Python are examples of scripting languages. (Wepopedia)(Wepopedia) 6/28/2016 19

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