what are network topologies with structure?

WHAT ARE NETWORK TOPOLOGIES WITH STRUCTURE?

The topology of a network is the structure defined by the interconnection scheme. This structure can be viewed as a graph with vertices representing the switching nodes and the branches representing the transmission channels. 

The choice of topology involves many interrelated factors:

1. Expected traffic
2. Routing method
3. channel capacity
4. cost

The various topologies are:

1. Mesh
2. Ring
3. Bus
4. Tree
5. Star

 Mesh Topology

In this type of structure each node is directly connected to every other node. Each device has a point to  point link with each other device. This topology provides alternative routes between nodes. A very large wire length is required and cost may become too high to be justified. 

Mesh topology

Public and private data communication networks use this kind of topologies. It is also known as fully connected topology.

Ring topology

In this topology , the host computer and workstation are connected in series forming a complete ring, for data communication . The links are unidirectional (clockwise/anticlockwise). 

Ring topology

It is economical and no collision of data takes place between two workstations. Problem arises while adding new devices in the networking series. It is used in LANs.

BUS topology

In this kind of structure, there is no central host computer. There is a single data cable which is shared by the workstations . It allows flexible networking as devices can be easily attached. It is economical , because single cable is involved possibility of data collision occurs.

Bus topology

Tree Topology

It is also known as hierarchical or vertical network. There may be more than one central nodes as it follow tree like architecture.

 It one center fails, the network can continue to be partially operational . This kind of structure is used in Remote access networks.

Tree topology

Star Topology

In this, different workstations are connected by cables with the centrally located host computer known as server or HUB. 

Star topology

The server is responsible for routing traffic and fault isolation. The failure of workstation does not effect structure but failure of centrally located host computer, HUB causes  complete  breakdown of communication network.

What is Binary, Octal and Hexadecimal Number System

Binary and Octal Number System

The base of Binary Number system is 2 because it consists of two different  digits or symbols i.e. 0 and 1. The digits 0 and 1 are called binary digits  commonly abbreviated as bit. 

Thus a “bit” in computer  terminology means either a ‘0’ or a ‘1’.

Each position in a binary number represents a power of the base (2) . 

In this system, the rightmost position is the units (2⁰) position, the second position from the right is the 2’s (2¹) position and then 4’s (2²) position, 8’s (2³) position, 16’s (2⁴) position and so on.

Thus, the decimal equivalent of the binary number 11010 is:

           (1×2⁴) + (1×2³) + (0×2²) + (1×2¹) + (0×2⁰)

or       16+8+0+2+0

or       26

In order to represent any number in different number system, place that number in a bracket and indicates its base as a subscript.

Thus, we can write

(11010)₂ = (26)₁₀

A binary number consisting of n bits is called an n-bit number. Only 8 or (2)³different patterns of 0’s and 1’s are possible with a 3-bit number. 

3-bit Numbers with their Decimal Equivalents

Octal Number System

In the Octal Number system, the base is 8. There are only eight symbols or digits : 0,1,2,3,4,5,6,7

Each position in a octal number represents a power of the base 8. The decimal equivalent of the octal number 4075 is:

        (4×8³) + (0×8²) + (7×8¹) + (5×8⁰)

or     2048+0+56+5

or     2109

so,    (4075)₈ = (2109) ₁₀

Since there are only 8 digits in the octal number system , 3 bits (2³=8) are sufficient to represent any octal number in binary.

Hexadecimal Number System

In the hexadecimal number system, the base is 16. The first 10 digits are the digits of a decimal system 0,1,2,3,4,5,6,7,8,9. 

The remaining six digits are denoted by A,B,C,D,E, F representing the decimal values 10,11,12,13,14,15 respectively. The largest single digit is F or 15. Each position in a hexadecimal system represents  a power of base (16).

The decimal equivalent of the hexadecimal number 2BE is:

          (2×16²) + (B×16¹) + (E×16⁰)

or      (2×256) + (11×16) + (14×1)

or      522+176+14

or       712

Thus, (2BE)₁₆ = (712)₁₀

_{4-bits can represent any hexadecimal number in binary:}

main services on the Internet?

SERVICES ON THE INTERNET      

 

Email

Email stands for Electronic Mail. It is a method of exchanging messages between users over the Internet. It is the fastest way of sending mails. some of the popular websites which provide email facility are:
www.yahoo.comwww.gmail.comwww.rediffmail.com

Chatting

An online conversation on the Internet through which you can send text based messages to one another instantly is called chatting.

There are some popular chat software available on the Internet, like Hangout, Yahoo Messenger, Skype, Windows Live Messenger, etc.

E-Learning

E-Learning refers to the use of Internet in teaching and learning. You can use the Internet in doing your task and assignments. It increases your knowledge and skills.

 E-Learning has now been used by various companies, organizations and schools to educate and upgrade the abilities of their students and employees.

E-Banking

E-Banking stands for electronic banking. This is a way of performing transactions and some other tasks of bank by using Internet. you can check the amount, transfer the money, make Fixed Deposit (FD), etc. Using e-banking you can perform all these activities from any part of the world.

E-Commerce

E-Commerce is the process of buying and selling of products or services over the Internet. It is a type of business on the Internet. People can order and purchase the items over the Internet from any of the world.

Video Conferencing

It is a process of exchanging the messages through sounds and images with face to face conversation . The users can also see each other . 

This technology is mainly used for political, business and social affairs. You may have seen the video conferrencing on the news channels on T.V.

Social Networking Sites

Social networking is like a group of individuals who share their ideas , activities, messages, photos, and videos. Some of the popular networking sites are Facebook , Linkedin, etc. A user must have a profile to use a social networking site.

What are Html Tags and Elements in web designing?

What are Html Tags and Elements in web 

designing?

TAGS

Tags are the labels which are used to mark up the start and end of an element. Tags are commands inserted in a document that specifies how the document should be formatted .

The structure of an HTML tag consists of the following terms:

• Every HTML tag has a tag name, followed by an optional list of attributes , and with opening and closing angle brackets (<>). For example , <HTML>

• Tag attributes  always come after the tag name, each separated by one or more space.

• A value of a tag attribute always comes after an equal (=) sign in quotes. For example , <A href=" http://www.google.com">

Types of Tags

Following are the two types of tags in HTML :

1.Container Tags (Paired Tags) : 

The tags which include an opening as well as closing tag are called container tags.

Example:

<HTML>-----------------------------</HTML>

<HEAD>-------------------------------</HEAD>

<TITLE>--------------------------------</TITLE>

<B>--------------------------------------</B>

<CENTER>-----------------------------</CENTER>

2.Empty Tags ( Singular Tags): 

The tags that have a no companion tag means they include only opening tag are called empty tags.

Example:

<BR>

<HR>

<BASE>

<IMG>

<LINK>

HTML Elements

An element is the basic building block of HTML and is typically made up of two tags :an opening tag and a closing tag.

There are two categories of HTML elements:

Block Level Elements:

They include the tags for Paragraph <P>, Heading Levels <Hn>, Horizontal Rule <HR>, etc.

Text Level Elements:

They are used for making up of bits of text including inserting images, sounds, etc. some commonly used text level elements are Bold <B>, Italic <I>, Line Break <BR>, etc.

STRUCTURE OF AN HTML DOCUMENT

The structure of an HTML document is as follows:

                                            

Sections	Description
Header Section	It contains the header of the html document.
Body Section	It contains the contents of the html document

The structure of an HTML document contains some basic HTML tags that are used to create an HTML document. Let us learn these tags.

HTML BASIC TAGS

Following are the basic HTML tags to create an HTML document.

HTML Tag

The <HTML> tag is used to mark the beginning of an HTML document. It informs the browser to know that it is dealing with an HTML document. It does not impact the appearance of contents of the document. Inside the <HTML> tag <HEAD> and <BODY> tags are usually included.

Syntax:  <HTML>-------------------------------------</HTML>

HEAD Tag

The <HEAD> tag defines the document header. It contains the information about a document , its titile and document’s description . It is written inside HTML tag.

Syntax: <HEAD>--------------------------------</HEAD>

TITLE Tag

The <TITLE> tag contains the title of the document. the title is displayed in the titlebar at the top of the web browser.

Syntax: <TITLE>--------------------------------------</TITLE>

BODY Tag

The <BODY> tag contains all the contents of a document or a web page.

Syntax: <BODY>-------------------------------------</BODY>

Example:

<html><head>

<title>My first HTML document</title>

</head>

<body>

Welcome to HTML

</body>

</html>


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For further reading:

• what is internet and its basic history
• Basic terms should be know of the internet to use it easily
• binary subtraction and multiplication in number system

How to browse the Internet step by step [components of Internet]

BROWSING THE INTERNET

 How to browse the Internet step by step [components of Internet]

How to browse the Internet : To broswse the Internet on your  computer, follow the steps as given below:

Step1.  Switch ON the modem and the computer.

Step2. Click the  Log in button of software and connect to the Internet.

Step3. Click the Internet Explorer or Google Chrome browser icon or any browser which you have in your computer.

Step4. Type the URL of the website in the address bar and press Enter Key.

web browser Internet Explorer 

The webpage of that particular website opens in the Internet Explorer Window.

The main components of the Internet explorer are as follows:

Title Bar

The title bar displays the name of the current webpage. It has three buttons – Minimize, Maximize  and Close.

minimize,maximize,close buttons

Address Bar

Address Bar is used to type the address of websites in its address box. After typing, press the Enter key to open the webpage or website.

Address bar contains the following buttons:

Refresh button : 

refresh button

Sometimes , a webpage is not opened or displayed completely, so you need to refresh the web page. The Refresh button allows you to start reloading of the webpage.

Stop button: 

stop button

The stop button is used to stop the loading of the webpage.

Back button :

back button

The back button is used to go to the previously opened web page.

Forward button :

forward button

The forward button is used to go to the next web page.

Recent Pages button:

When you click  on this button, it shows a list of recently opened web pages. This also contains a history button which shows the list of  visited web pages.

Command Bar

The command bar is present in the right-hand corner of the page. It contains  different buttons such as:

Home button :

home button

The home button is used to go to the home page of the website. Home page is the first page when you open a website.

Print button: 

The print button is used to take a printout of the pages.

Page button: 

The page button contains a lot of options such as Save the page, Reload the page , etc. A list of options appears when you click on this button.

Status Bar

Status bar is located at the bottom of the window that displays the number of elements to be viewed on a web page and the progress of the web page being displayed.

Scrollbars

Scrollbars appear on the side or bottom of a window to control which part of a list or document is currently in the window’s frame. Horizontal and vertical scroll bars are used to move the web page horizontally and vertically respectively.

Search Engines

A search engine is a web based tool that allows users to search the information on the World Wide Web. Some of the popular search engines are Google, Yahoo, Bing ,etc. Google search engine is most widely used search engine on the web.

bing search engine

By using search engine, you may search for books, games, songs, pictures  and some other information. Search engine searches databases and Internet sites for the documents containing keywords that are specified by a user.

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Basic terms should be know of the internet to use it easily

                

BASIC TERMS OF THE INTERNET

We can describe the basic terms of the Internet into following ways:

World Wide Web

basic terms of the internet: World Wide Web (WWW) is a subset of Internet that contains huge amount of information . This information includes text, graphics, audio, video, etc. WWW allows the users to access the data on the Internet. WWW is also called web.

Web page

It is a page on the Internet that contains the information in the form of text, graphics or sounds. A web can be accessed through a web browser on the Internet. Web pages are the building  blocks of a website.

Web Browser

A web browser is a software application that enables the users to access, a retrieve and view the information  and other resources  on the Internet. Term internet service providers different web browsers are user friendly to run it easily.

Some of the popular web browsers are:

Internet Explorer

mozilla firefox

opera

Chrome

Website

A website is a collection of interrelated web pages that provide information to the user For a commercial organization , it enables its potential customers to learn about the organization, its products or services. Some websites also allow the users to place orders electronically. Each site is owned and managed by an individual, company or organization.

Home Page

A home page is the main or introductory page of a website. It is the first page that appears when you open the website. It usually contains the table of contents and links to other pages. 

Yahoo Home page

The home page is used to facilitate navigation to other pages on the site, by providing links to important  and recent articles and pages, and possibly a search box.

Hyperlinks

A web page consists of text, pictures,  sounds and hyperlinks. A hyperlink is a reference to data that the reader can directly follow either by clicking or by hovering. 

hyperlink Icon

A hyperlink may be a text or picture. It connects the users to other parts of the same web page or other related web pages. 

When you move the cursor over a hyperlink , like text or an image, the arrow will change to a small hand pointing  at the link. When you click it, a new page or place in the current page will open. Hyperlink is also often referred to as “link”.

Uniform Resource Locator (URL)

Uniform Resource Locator (URL) refers to the address or the location of a web page or the website on the Internet. Each website on the Internet. Each website on the Internet has a unique address.

Most web browsers display the URL of a web page above the page in an address  bar. 

For example, https://www.google.com/ is a URL.

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