Internet and Related Terminology

INTERNET AND RELATED TERMINOLOGY

1. INTERNET:-is a worldwide n/w of n/ws can be defined as a global n/w of over a million of smaller heterogeneous computer n/ws. The internet is the common language where by dissimilar computers with various operating systems, are able to communicate with each other ,using set of protocols(rules).

2. INTERNET SERVICE PROVIDERS(ISP’s):-worldwide offer various options and packages to the general public for internet access. ISP is a company which gives us the facility to gain access to the internet against a fee. Some ISP’s in INDIA are VSNL,MTNL,Mantra online etc.

3.INTERNET ADDRESSING:-Domain Name System-An addressing system was designed by the Internet Engineering Task Force(IETF).This addressing scheme assigns names and numbers to identify the computers on the internet. The names are called domain names and the numbers are called IP addresses. Domain name system(DNS) is a distributed database system for translating computer names into a numeric IP address. A domain name always contains two or more components separated by period called ‘dots’.IP addresses are in the number format xxx.xxx.xxx.xxx,where each xxx is a number from 0 to 255.IP addresses identify the host computers. IP address is called the host address.

4.WWW:-World Wide Web is a internet service, based on a common set of protocols, which allows a server computer to distribute documents across the Internet in a standard way. The WWW is an example of Client-Server technology. Internet user using a software known as the Web Browser ,requests a document located on the web. The browser acts like a customer or a client and requests for the information. The internet host serves the information and thus is called the Server. The flow of information is controlled by a protocol HTTP(Hyper Text Transport Protocol).

5.UNIFORM RESOURCE LOCATER(URL):-The technique used to address documents on the Web is called URL.It provides an addressing scheme which allow the browser to request about any document or web page.A URL normally takes the form

For example :-http:www.microsoft.com/IE/index.htm

Domain Name- An internet address which is character based is called a Domain Name.

6.Interspace: It is a client /server software program that allows multiple users to communicate online with real time audio, video and text chat in dynamic 3D environment.

7.Relative URL:-A Relative URL is not fully qualified ,but rather it inherits the protocol,host and path information from its parent document.They are used for accessing files when the full internet address is unnecessary.When Relative URL’s are accessed ,the base part of the URL is automatically

8. The different protocols for URL’s are-http://,HTML documents,gopher://Gopher menus and documents,news://usenet news group,telnet:Remote Telnet(login)Session

9.HTTP:- A web page is created by using a specialised language called HTML.(Hyper Text Markup Language).Web pages are requested by Internet users or clients from the internet host or servers and are served or transported over the internet using a protocol called HTTP(Hyper Text Transport Protocol).

10. Web Server:-It is the job of web server to accept connections from web browsers all over the internet and when requested ,send them the HTML documents that are available from your server.It is a computer with an internet connection that runs software designed to send out HTML pages and other file formats.

11. WEB SITE:- A web site is a collection of web pages belonging to a particular person or organization.

12. WEB PAGE:-A Web Page is single unit of information,,often called a document that is available via the worldwideWeb(WWW).A web page is an HTML document that is stored on a web server and that has a URL so that it can be accessed via a web. It is a document that uses HTTP.

WEB HOSTING- It is a means of hosting web server application on a computer system through which electronic content on the internet is readily available to any web browser client.

WEB PORTAL- It is a web site which hosts other web sites.

13. HOME PAGE(‘FRONT DOOR’):-The HomePage is the front door of the site and is set up to help viewers to find whatever is of interest of them on that site.The URL of the homepage also serves as the URL of the web site e.g. http://www.microsoft.com/ms.htm is a web site.

14. WEB BROWSER:-is a client application that requests,recieves and display HTML pages. It is a program that your computer runs to communicate with web servers on the internet, which enables it to download and display the web-pages that you request. The most popular browsers are –1.INTERNET EXPLORER 2.Netscape Navigator 3. NCSA MOSAIC

15.HTML:-Hyper Text Markup Language:-It is designed to specify the logical organization of a document,with important hypertext extensions.HTML instructions divide the text of a document into blocks called elements.These can be divided into two broad categories –those that define the body of the document is to be displayed by the browser ,and those that define information ‘about’ the document ,such as the title or relationships to other documents.

16.DHTML:-Dynamic HTML- is typically used to describe the combination of HTML ,style sheets and scripts that allows documents to be animated. The above of scripting add dynamism to the web page.

Difference: Web Pages created through HTML are static i.e. they appear the same every time they are viewed but web pages created through DHTML are dynamic i.e. their appearance may change upon viewing

17 XML:-Extended Markup Language-XML is a markup language for creating documents containing structured information.

Difference: In HTML both tag semantics and tag set are fixed but XML specifies neither semantics nor tagset. Rather it provides a facility to define tags and relationships among them.

18. E-mail(Electronic mail):- Advantages-(1).cost effective (2).instantaneous(very fast). ?(3). Offers non-intrusive medium (4).convenient to use (5).usability.

Limitations- (1).security and privacy of E-mail-Hackers can get access to your mail box. (2). Impersonal medium-difficult to express emotions

19.E-mail Address-E-mail address is made up of two parts:-the user name and the host name(fullu qualified Domain Name of the server or host on which user has an account).Two parts are separated by “@” symbol.No two persons can have same user name.

20. SEARCH ENGINES- are a Bottom-Up approach to find your way around the Web. You give a search engine a list of query and it returns to you a list of web pages that contain those words.It provides an interface between the use and the underlying database e.g.Alta Vista is one of the oldest search engines on the web. Excite , HOTBOT and Infoseek are some examples of Search Engines.

21. CHAT SERVICES-uses a specialised s/w that allows the user to type some comment in on window and receive some replies in another from someone who is accessing the same s/w.Web sites that enable you to converse with other web users are called CHAT .These sites are referred to as Chat rooms.

22. VOICE CONFERENCING & VIDEO CONFERENCING-Voice Conferencing is talking to another person via the microphone and speakers connected to your computer. Video Conferencing is sending your image and voice to one or more other people,through the camera and microphone attached to your computer.

23. DOWNLOADING & UPLOADING-The most popular form of file transfer is to download files from the web.The concept of uploading means to transfer files from your host computer to other computers through modem.Netscape Navigator and certain other browsers can also upload files.

24. (ELECTRONIC) E- COMMERCE-buying and selling of products and services over the Internet.

25. USENET-A system in which thousands of newsgroups enable to exchange news on huge subjects.They are the discussion groups in the internet ,where people gather to post messages and replies on thousands of topics.

FINDING THINGS ON INTERNET

26. ARCHIE-tries to locate files in public FTP archives.It searches for the file names or partial names.Archie searches its database and informs you about all the files that match.

27. VERONICA-one of the menu item of GOPHER. This tool takes you to the Gopher servers ,which contain specific information ,you are searching for.Veronica builds a special Gopher menu for you consisting of all the menu items in its databse that matches the words asked by you.

28. WAIS(Wide Area Information Server)-It is pronounced as ‘ways’,maintains separate indexes of the contents of selected documents.You can choose any index and provide WAIS with the Keywords you are looking for.

29.MOSAIC-is a program for cruising the Internet.It has a simple windows interface ,which creates useful hypertext links that automatically performs menu bar and button functions.

NETWORK

1. NETWORK-is an interconnected connection of autonomous computers.Two computers are said to be interconnected if they are capable of exchanging information.It allows computers to share computer equipment and programs. Need for networks are:

(a) Resource Sharing: data, hardware and software resources can be shared irrespective of physical location.

(b) Reliability: file can have two or more copies on different systems, in case if one is unavailable we can use the other.

(d) Fast communication: exchange information fast.

2. NODES(Work station)-The different terminals which are attached to the network and share the resources of the network are called nodes.When we attach a computer with the n/w it becomes the workstation of that n/w.

3. SERVER:-To designate a particular node,which is at a well known and fixed address,to provide a service to the n/w as a whole.The node providing the service is known as the server. A computer that facilitates the sharing of data, software and hardware resources on a network, is called server. It can be of two types.

Non-dedicated server: It is a workstation on a small network that can also act as a server.

Dedicated server: On bigger networks, a computer is reserved for the cause of serving which is called a dedicated server.

4.NETWORK INTERFACE UNIT:-The interpreter, which helps in the communication between the server and different nodes,is called NIU. The NIU is also called TAP(Terminal Access Point) or NIC (Network Interface Card).

The NIC manufacturer assigns a unique physical address to each NIC card

5.TYPES OF N/W(WAN-wide area n/w,MAN-metropolitan area n/w,LAN-local area n/w).

6. COMMUNICATION CHANNELS:-connect two or more workstations by using cables.The connecting cables between the different workstations.

(a). Twisted Pair Cable:- As a Voice Grade Medium(VGM),it is the basis for most internal offices telephone wiring.It consists of two identical wires in the pair have the same impedance to ground,making it a balanced medium.

Main advantage of this medium is it is capable of carrying a signal over long distances without the use repeaters.It is perfectly adequate medium for low speed (upto 10 mbps)applications where the distance between nodes is small.

Advantages-simple,easy to install and maintain,physically flexible,easily connected and inexpensive.

Disadvantages-Incapable of carrying signals over long distances,low bandwidth.It supports data rate 1MBPS to 10 MBPS.

(b). COAXIAL CABLE:-consists of a solid wire core surrounded by one or more foil or wire shields,each separated by some kind of plastic insulator.

Advantages-data transmission is better than twisted pair cables,can be used as basis for a shared cable n/w,can be used for broadband transmission ,and offers higher bandwidths upto 400 MBPS.

Disadvantages-Expensive compared to twisted pair cables.It is not compatible with twisted pair cables.

(c). OPTICAL FIBRES:-consists of thin strands of glass or glass like material which are also constructed so that they can carry light from a source at one end to detector at the other end.The light source used are either Light Emitting Diodes(LEDs) or Laser Diodes(LDs).

Advantages-It is immune to electrical and magnetic interference,highly suitable for harsh industrial environment.It has got a very high transmission capacity.

Disadvantages-Installation problem.These are quite fragile and needs special care.connecting the fibres together or a light source to a fibre is a difficult process. They are the most expensive of all the cables.

(d). MICRO-WAVE:-signals are used to transmit data without the use of cables.It is similar to radio and television signals and are used for long distance communication.Transmission consists of a transmitter,reciever and the atmosphere.

Advantages-cheaper than digging tenches for laying cables.It offers ease of communication over difficult terrian as well as over oceans.

Disadvantages-It is an insecure communication.The microwave propagation is susceptable to weather effects like rains,stroms etc.Bandwidth allocation is extremely limited.

(e). RADIO-WAVE:-Transmission making use of radio frequencies.Any radio setup has two parts:the Transmitter and the Reciever.

Advantages-offers mobility.It proves cheaper than digging trenches for laying cables.It offers ease of communication over difficult terrain.

Disadvantages-Insecure communication.Radio wave propagation is susceptable to weather effects like rains,thunder stroms etc.

(f) SATELLITE:-The frequency is higher than 3GHz.The earth station consists of a satellite dish that functions as an antenna and communication equipment to transmit and receive data from satellites.

Advantages-Area coverage is quite large.It proves cheaper than digging trenches for laying cables.The heavy usage of intercontinental traffic makes the satellite commercialy attractive,it can cover large area.

Disadvantages-High investment cost.High atmospheric loses above 30 Ghz limit carrier frequencies.

COMMUNICATION PROTOCOLS

PROTOCOL-is a formal description of message formats and the rules that two or more machines must follow to exdchange those messages.

1. HTTP(Hyper Text Transfer Protocol)-is an application level protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems. It is a generic, stateless, object oriented protocol which can be used for many tasks such as name servers and distributed object management systems through extension of its request methods.

2. FTP(File Transfer Protocol):-Files of any type can be transferred, although you may have to specify whether the file is an ASCII or Binary file.It is a potent and popular way to share information over the internet.

3. TCP/IP(Transmission Control Protocol/Internet Protocol):-It is a layered set of protocols.TCP is responsible for making sure that the commands gets through to the other end.It keeps tracks of what is sent and retransmits anything that did not get through .TCP will split information into several datagrams,which make sure that they all arrive correctly.DATAGRAM is a collection of data that is sent as a single message.

TCP:-

· Breaks data into packets that the internet can handle.