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Internet is defined as an Information super Highway, to access information over the web. However, It can be defined in many ways as follows:
Internet is a world-wide global system of interconnected computer networks.
Internet uses the standard Internet Protocol (TCP/IP).
Every computer in internet is identified by a unique IP address.
IP Address is a unique set of numbers (such as 110.22.33.114) which identifies a computer location.
A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name.
For example, a DNS server will resolve a name https://www.abhipedia.abhimanu.com to a particular IP address to uniquely identify the computer on which this website is hosted.
Internet is accessible to every user all over the world.
The concept of Internet was originated in 1969 and has undergone several technological & Infrastructural changes as discussed below:
The origin of Internet devised from the concept of Advanced Research Project Agency Network (ARPANET).
ARPANET was developed by United States Department of Defense.
Basic purpose of ARPANET was to provide communication among the various bodies of government.
Initially, there were only four nodes, formally called Hosts.
In 1972, the ARPANET spread over the globe with 23 nodes located at different countries and thus became known as Internet.
By the time, with invention of new technologies such as TCP/IP protocols, DNS, WWW, browsers, scripting languages etc.,Internet provided a medium to publish and access information over the web.
Internet covers almost every aspect of life, one can think of. Here, we will discuss some of the advantages of Internet:
Internet allows us to communicate with the people sitting at remote locations. There are various apps available on the wed that uses Internet as a medium for communication. One can find various social networking sites such as:
Facebook
Twitter
Yahoo
Google+
Flickr
Orkut
One can surf for any kind of information over the internet. Information regarding various topics such as Technology, Health & Science, Social Studies, Geographical Information, Information Technology, Products etc can be surfed with help of a search engine.
Apart from communication and source of information, internet also serves a medium for entertainment. Following are the various modes for entertainment over internet.
Online Television
Online Games
Songs
Videos
Social Networking Apps
Internet allows us to use many services like:
Internet Banking
Matrimonial Services
Online Shopping
Online Ticket Booking
Online Bill Payment
Data Sharing
E-mail
Internet provides concept of electronic commerce, that allows the business deals to be conducted on electronic systems
However, Internet has prooved to be a powerful source of information in almost every field, yet there exists many disadvanatges discussed below:
There are always chances to loose personal information such as name, address, credit card number. Therefore, one should be very careful while sharing such information. One should use credit cards only through authenticated sites.
Another disadvantage is the Spamming.Spamming corresponds to the unwanted e-mails in bulk. These e-mails serve no purpose and lead to obstruction of entire system.
Virus can easily be spread to the computers connected to internet. Such virus attacks may cause your system to crash or your important data may get deleted.
Also a biggest threat on internet is pornography. There are many pornographic sites that can be found, letting your children to use internet which indirectly affects the children healthy mental life.
There are various websites that do not provide the authenticated information. This leads to misconception among many people.
Intranet is defined as private network of computers within an organization with its own server and firewall. Moreover we can define Intranet as:
Intranet is system in which multiple PCs are networked to be connected to each other. PCs in intranet are not available to the world outside of the intranet.
Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intranet.
Each computer in Intranet is also identified by a IP Address, which is unique among the computers in that Intranet.
Intranet is very efficient and reliable network system for any organization. It is beneficial in every aspect such as collaboration, cost-effectiveness, security, productivity and much more.
Intranet offers easy and cheap communication within an organization. Employees can communicate using chat, e-mail or blogs.
Information on Intranet is shared in real time.
Information is distributed among the employees as according to requirement and it can be accessed by the authorized users, resulting in enhanced teamwork.
Intranet can connect computers and other devices with different architecture.
Employees can see the data and other documents using browser rather than printing them and distributing duplicate copies among the employees, which certainly decreases the cost.
Data is available at every time and can be accessed using company workstation. This helps the employees work faster.
It is also possible to deploy applications that support business operations.
Since information shared on intranet can only be accessed within an organization, therefore there is almost no chance of being theft.
Intranet targets only specific users within an organization therefore, once can exactly know whom he is interacting.
Any changes made to information are reflected immediately to all the users.
Apart from several benefits of Intranet, there also exist some issues.. These issues are shown in the following diagram:
Intranet applications are same as that of Internet applications. Intranet applications are also accessed through a web browser. The only difference is that, Intranet applications reside on local server while Internet applications reside on remote server. Here, we've discussed some of these applications:
Document publication applications allow publishing documents such as manuals, software guide, employee profits etc without use of paper.
It offers electronic resources such as software applications, templates and tools, to be shared across the network.
Like on internet, we have e-mail and chat like applications for Intranet, hence offering an interactive communication among employees.
Intranet offers an environment to deploy and test applications before placing them on Internet.
Apart from similarities there are some differences between the two. Following are the differences between Internet and Intranet:
Extranet refers to network within an organization, using internet to connect to the outsiders in controlled manner. It helps to connect businesses with their customers and suppliers and therefore allows working in a collaborative manner.
Extranet is implemented as a Virtual Private Networks (VPN) because it uses internet to connect to corporate organization and there is always a threat to information security. VPN offers a secure network in public infrastructure (Internet).
Key Points
The packet is encapsulated at boundary of networks in IPSEC complaint routers.
It uses an encryption key to encapsulate packets and IP addresses as well.
The packet is decoded only by the IPSEC complaint routers or servers.
The message is sent over VPN via VPN Tunnel and this process is known as tunneling.
VPN uses Internet Protocol Security Architecture (IPSEC) Protocol to provide secure transactions by adding an additional security layer to TCP/IP protocol. This layer is created by encapsulating the IP packet to a new IP packet as shown in the following diagram:
Extranet proves to be a successful model for all kind of businesses whether small or big. Here are some of the advantages of extranet for employees, suppliers, business partners, and customers:
Domain Name System helps to resolve the host name to an address. It uses a hierarchical naming scheme and distributed database of IP addresses and associated names
IP address is a unique logical address assigned to a machine over the network. An IP address exhibits the following properties:
IP address is the unique address assigned to each host present on Internet.
IP address is 32 bits (4 bytes) long.
IP address consists of two components: network component and host component.
Each of the 4 bytes is represented by a number from 0 to 255, separated with dots. For example 137.170.4.124
IP addresses are difficult to remeber while on the other hand domain names are easy to remember names.
Uniform Resource Locator (URL) refers to a web address which uniquely identifies a document over the internet.
This document can be a web page, image, audio, video or anything else present on the web.
For example, https://abhipedia.abhimanu.com/default.aspx is an URL to the default page which is stored on web server .
There are two forms of URL as listed below:
Absolute URL
Relative URL
Absolute URL is a complete address of a resource on the web. This completed address comprises of protocol used, server name, path name and file name.
For example http:// www.tutorialspoint.com / internet_technology /index.htm. where:
http is the protocol.
tutorialspoint.com is the server name.
The protocol part tells the web browser how to handle the file. Similarly we have some other protocols also that can be used to create URL are:
FTP
https
Gopher
mailto
news
Relative URL is a partial address of a webpage. Unlike absolute URL, the protocol and server part are omitted from relative URL.
Relative URLs are used for internal links i.e. to create links to file that are part of same website as the WebPages on which you are placing the link.
Difference between Absolute and Relative URL
The Domain name system comprises of Domain Names, Domain Name Space, Name Server that have been described below:
Domain Name is a symbolic string associated with an IP address. There are several domain names available; some of them are generic such as com, edu, gov, net etc, while some country level domain names such as au, in, za, us etc.
The following table shows the Generic Top-Level Domain names:
The following table shows the Country top-level domain names:
The domain name space refers a hierarchy in the internet naming structure. This hierarchy has multiple levels (from 0 to 127), with a root at the top. The following diagram shows the domain name space hierarchy:
Internet Services allows us to access huge amount of information such as text, graphics, sound and software over the internet. Following diagram shows the four different categories of Internet Services.
There are various Communication Services available that offer exchange of information with individuals or groups. The following table gives a brief introduction to these services:
There exist several Information retrieval services offering easy access to information present on the internet. The following table gives a brief introduction to these services:
Web services allow exchange of information between applications on the web. Using web services, applications can easily interact with each other.
The web services are offered using concept of Utility Computing.
WWW is also known as W3. It offers a way to access documents spread over the several servers over the internet. These documents may contain texts, graphics, audio, video, hyperlinks. The hyperlinks allow the users to navigate between the documents.
Video conferencing or Video teleconferencing is a method of communicating by two-way video and audio transmission with help of telecommunication technologies.
This mode of conferencing connects two locations only.
This mode of conferencing connects more than two locations through Multi-point Control Unit (MCU).
Here in this tutorial, we will discuss how to connect to internet i.e. internet service providers, software and hardware requirements, configuring internet connection etc.
Internet Service Provider (ISP) is a company offering access to internet. They offer various services:
Internet Access
Domain name registration
Dial-up access
Leased line access
ISPs can broadly be classified into six categories as shown in the following diagram:
They provide access to internet through telephone lines, cable wi-fi or fiber optics.
Such providers offer mailbox hosting services.
Hosting ISPs offers e-mail, and other web hosting services such as virtual machines, clouds etc.
Such ISPs offer internet access via other ISP services.
Free ISPs do not charge for internet services.
There exist several ways to connect to the internet. Following are these connection types available:
Dial-up Connection
ISDN
DSL
Cable TV Internet connections
Satellite Internet connections
Wireless Internet Connections
Dial-up connection uses telephone line to connect PC to the internet. It requires a modem to setup dial-up connection. This modem works as an interface between PC and the telephone line.
There is also a communication program that instructs the modem to make a call to specific number provided by an ISP.
Dial-up connection uses either of the following protocols:
Serial Line Internet Protocol (SLIP)
Point to Point Protocol (PPP)
The following diagram shows the accessing internet using modem:
ISDN is acronym of Integrated Services Digital Network. It establishes the connection using the phone lines which carry digital signals instead of analog signals.
There are two techniques to deliver ISDN services:
Basic Rate Interface (BRI)
Primary Rate Interface (PRI)
Key points:
The BRI ISDN consists of three distinct channels on a single ISDN line: t1o 64kbps B (Bearer) channel and one 16kbps D (Delta or Data) channels.
The PRI ISDN consists of 23 B channels and one D channels with both have operating capacity of 64kbps individually making a total transmission rate of 1.54Mbps.
The following diagram shows accessing internet using ISDN connection:
DSL is acronym of Digital Subscriber Line. It is a form of broadband connection as it provides connection over ordinary telephone lines.
Following are the several versions of DSL technique available today:
Asymmetric DSL (ADSL)
Symmetric DSL (SDSL)
High bit-rate DSL (HDSL)
Rate adaptive DSL (RDSL)
Very high bit-rate DSL (VDSL)
ISDN DSL (IDSL)
All of the above mentioned technologies differ in their upload and download speed, bit transfer rate and level of service.
The following diagram shows that how we can connect to internet using DSL technology:
Cable TV Internet connection is provided through Cable TV lines. It uses coaxial cable which is capable of transferring data at much higher speed than common telephone line.
Key Points:
A cable modem is used to access this service, provided by the cable operator.
The Cable modem comprises of two connections: one for internet service and other for Cable TV signals.
Since Cable TV internet connections share a set amount of bandwidth with a group of customers, therefore, data transfer rate also depends on number of customers using the internet at the same time.
The following diagram shows that how internet is accessed using Cable TV connection:
Satellite Internet connection offers high speed connection to the internet. There are two types of satellite internet connection: one way connection or two way connection.
In one way connection, we can only download data but if we want to upload, we need a dialup access through ISP over telephone line.
In two way connection, we can download and upload the data by the satellite. It does not require any dialup connection.
The following diagram shows how internet is accessed using satellite internet connection:
Wireless Internet Connection makes use of radio frequency bands to connect to the internet and offers a very high speed. The wireless internet connection can be obtained by either WiFi or Bluetooth.
Wi Fi wireless technology is based on IEEE 802.11 standards which allow the electronic device to connect to the internet.
Bluetooth wireless technology makes use of short-wavelength radio waves and helps to create personal area network (PAN).
TCP is a connection oriented protocol and offers end-to-end packet delivery. It acts as back bone for connection.It exhibits the following key features:
Transmission Control Protocol (TCP) corresponds to the Transport Layer of OSI Model.
TCP is a reliable and connection oriented protocol.
TCP offers:
Stream Data Transfer.
Reliability.
Efficient Flow Control
Full-duplex operation.
Multiplexing.
TCP offers connection oriented end-to-end packet delivery.
TCP ensures reliability by sequencing bytes with a forwarding acknowledgement number that indicates to the destination the next byte the source expect to receive.
It retransmits the bytes not acknowledged with in specified time period.
TCP offers following services to the processes at the application layer:
Stream Delivery Service
Sending and Receiving Buffers
Bytes and Segments
Full Duplex Service
Connection Oriented Service
Reliable Service
TCP protocol is stream oriented because it allows the sending process to send data as stream of bytes and the receiving process to obtain data as stream of bytes.
It may not be possible for sending and receiving process to produce and obtain data at same speed, therefore, TCP needs buffers for storage at sending and receiving ends.
The Transmission Control Protocol (TCP), at transport layer groups the bytes into a packet. This packet is called segment. Before transmission of these packets, these segments are encapsulated into an IP datagram.
Transmitting the data in duplex mode means flow of data in both the directions at the same time.
TCP offers connection oriented service in the following manner:
TCP of process-1 informs TCP of process – 2 and gets its approval.
TCP of process – 1 and TCP of process – 2 and exchange data in both the two directions.
After completing the data exchange, when buffers on both sides are empty, the two TCP’s destroy their buffers.
For sake of reliability, TCP uses acknowledgement mechanism.
Internet Protocol is connectionless and unreliable protocol. It ensures no guarantee of successfully transmission of data.
In order to make it reliable, it must be paired with reliable protocol such as TCP at the transport layer.
Like IP, UDP is connectionless and unreliable protocol. It doesn’t require making a connection with the host to exchange data. Since UDP is unreliable protocol, there is no mechanism for ensuring that data sent is received.
FTP is used to copy files from one host to another. FTP offers the mechanism for the same in following manner:
FTP creates two processes such as Control Process and Data Transfer Process at both ends i.e. at client as well as at server.
FTP establishes two different connections: one is for data transfer and other is for control information.
Control connection is made between control processes while Data Connection is made between
FTP uses port 21 for the control connection and Port 20 for the data connection.
Trivial File Transfer Protocol is also used to transfer the files but it transfers the files without authentication. Unlike FTP, TFTP does not separate control and data information. Since there is no authentication exists, TFTP lacks in security features therefore it is not recommended to use TFTP.
Key points
TFTP makes use of UDP for data transport. Each TFTP message is carried in separate UDP datagram.
The first two bytes of a TFTP message specify the type of message.
The TFTP session is initiated when a TFTP client sends a request to upload or download a file.
The request is sent from an ephemeral UDP port to the UDP port 69 of an TFTP server.
HTTP is a communication protocol. It defines mechanism for communication between browser and the web server. It is also called request and response protocol because the communication between browser and server takes place in request and response pairs.
HTTP request comprises of lines which contains:
Request line
Header Fields
Message body
The first line i.e. the Request line specifies the request method i.e. Get or Post.
The second line specifies the header which indicates the domain name of the server from where index.htm is retrieved.
Like HTTP request, HTTP response also has certain structure. HTTP response contains:
Status line
Headers
By: Brijesh Kumar ProfileResourcesReport error
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