Dip CSE 3rd Semester Internet and Web Technologies Notes

What is Internet

The internet is a globally connected network system facilitating worldwide communication and access to data resources through a vast collection of private, public, business, academic, and government networks. It is governed by agencies like the Internet Assigned Numbers Authority (or IANA) that establish universal protocols.

The terms internet and World Wide Web are often used interchangeably, but they are not exactly the same thing; the internet refers to the global communication system, including hardware and infrastructure, while the web is one of the services communicated over the internet.

Internet Application

Internet Applications can be described as the type of applications that use the internet for operating successfully, that is, by using the internet for fetching, sharing, and displaying the information from the respective server systems. It can be accessed only with the help of the internet facility, and it cannot be functional without the internet. These applications can be classified as electronic devices based, automated digital technology, industrial internet, smartphones based, smart home-based, smart grids, smart city, and other major applications.

The internet is treated as one of the biggest inventions.

It has a large number of uses.

  1. Communication
  2. Job searches
  3. Finding books and study material
  4. Health and medicine
  5. Travel
  6. Entertainment
  7. Shopping
  8. Stock market updates
  9. Research

 Business use of the internet: different ways by which the internet can be used for business are:

  • Information about the product can be provided online to the customer.
  • Provide market information to the business
  • It helps business to recruit talented people
  • Help in locating suppliers of the product.
  • Fast information regarding customers view about the company’s product
  • Eliminate middlemen and have direct contact with customers.
  • Providing information to the investor by providing companies background and financial information on web site.

Specification and technical details for establishing the Internet.

The Internet uses a set of network protocols called TCP / IP. In this article, we want to describe to you the standard protocols (Standard) and applications that have been developed to support these protocols. These protocols provide a standard method for transferring messages. They provide formats for messages and handle them in the event of a transmission failure. These protocols are independent of the network hardware, which means it allows communication between different networks with different hardware as long as they use the same type of protocol. The diagram below provides a classification chart of the protocols.

The primary piece of hardware you need is a modem. The type of Internet access you choose will determine the type of modem you need. Dial-up access uses a telephone modem, DSL service uses a DSL modem, cable access uses a cable modem, and satellite service uses a satellite adapter.

Types and functions of modems

MODEM’s full form is “Modulator-Demodulator” which means it has the ability to modulate and demodulate analog carrier signals for encoding and decoding digital data for executing. The modem is a hardware networking device that helps to make connections with computer or other hardware components like a switch or router for linking to the internet.

Purpose of Modem

Modems are used for performing both activities like sending and receiving the digital data in between with multiple computer systems. Then this data is transmitted over the telephone lines using V.92, to analog modems which help out for converting those signals back to digital form for the readable format to computer.

Types of Modem

There are different types of modem which are used in computer networking; below explain each one –

Dial-up Modem: Dial-up modems transmit analog signals via telephone lines. This modem is used mostly to make connections with ISP using analog signals. The dial-up modem has two variants like an external or internal modem.

Cable Modem: In the cable modem, use the coaxial cables that are connected to the back edge of the modem.

ADSL Modem: ADSL stands for “Asymmetric Digital Subscriber Line” and these types of modems use the telephone line for sending and receiving all information. ASDL modems have higher speed compared to conventional voice and modems.

ASDL modem uses two types of data transmission methods as “Synchronous and Asynchronous“. Synchronous transmission is used into more accurate for your timing signals but asynchronous transmission is used in mistaken correcting formulas.

DSL Modem: DSL stands for “Digital Subscriber Line“, and it is also known as “Broadband Modem“. DSL modems offer broadband services for using different types of internet connections. DSL modems are comfortable for higher internet speed.

External Modem: External modem likes a standalone modem because it doesn’t integrate any router. This modem is connected with the computer through a USB stick, WIFI, or Ethernet cable. It has an option for getting connected with a separate router if you want to share make a connection with several network terminals around the small zone.

Router/Modem Combo: This type of modem is contained with a router that allows several devices and computers to attach within a single network. So, users do not require an extra router and modem.

Integrated Modem: This modem is embedded into the computer in the form of a USB or PCI card. But, this type of modem allows an only a single computer system to make a connection with the internet.

Onboard Modem: Onboard modems are embedded onto the motherboard, so this modem has not any chance of removing them, but it can be disabled by using of jumper or BIOS setup.

Removable Modem: This modem can be inserted or removed as per the requirement, and these modems are used in traditional laptops PCMCIA slots.

Wireless Modem: Wireless Modem is also known as “Radiofrequency Modem“, and these modems are developed to work with cellular technology and wireless local area networks.

IP addressing

An IP address is a string of numbers separated by periods. IP addresses are expressed as a set of four numbers — an example address might be Each number in the set can range from 0 to 255. So, the full IP addressing range goes from to

IP addresses are not random. They are mathematically produced and allocated by the Internet Assigned Numbers Authority (IANA), a division of the Internet Corporation for Assigned Names and Numbers (ICANN). ICANN is a non-profit organization that was established in the United States in 1998 to help maintain the security of the internet and allow it to be usable by all. Each time anyone registers a domain on the internet, they go through a domain name registrar, who pays a small fee to ICANN to register the domain.

How do IP addresses work

If you want to understand why a particular device is not connecting in the way you would expect or you want to troubleshoot why your network may not be working, it helps understand how IP addresses work.

Internet Protocol works the same way as any other language, by communicating using set guidelines to pass information. All devices find, send, and exchange information with other connected devices using this protocol. By speaking the same language, any computer in any location can talk to one another.

The use of IP addresses typically happens behind the scenes. The process works like this:

  1. Your device indirectly connects to the internet by connecting at first to a network connected to the internet, which then grants your device access to the internet.
  2. When you are home that network will probably be your Internet Service Provider (ISP). At work, it will be your company network.
  3. Your IP address is assigned to your device by your ISP.
  4. Your internet activity goes through the ISP, and they route it back to you, using your IP address. Since they are giving you access to the internet, it is their role to assign an IP address to your device.
  5. However, your IP address can change. For example, turning your modem or router on or off can change it. Or you can contact your ISP, and they can change it for you.
  6. When you are out and about – for example, traveling – and you take your device with you, your home IP address does not come with you. This is because you will be using another network (Wi-Fi at a hotel, airport, or coffee shop, etc.) to access the internet and will be using a different (and temporary) IP address, assigned to you by the ISP of the hotel, airport or coffee shop.

As the process implies, there are different types of IP addresses, which we explore below.

Types of IP addresses

There are different categories of IP addresses, and within each category, different types.

Consumer IP addresses

Every individual or business with an internet service plan have two types of IP addresses: their private IP addresses and their public IP address. The terms public and private relate to the network location — that is, a private IP address is used inside a network, while a public one is used outside a network.

Private IP addresses

Every device that connects to your internet network has a private IP address. This includes computers, smart phones, and tablets but also any Bluetooth-enabled devices like speakers, printers, or smart TVs. With the growing internet of things, the number of private IP addresses you have at home is probably growing. Your router needs a way to identify these items separately, and many items need a way to recognize each other. Therefore, your router generates private IP addresses that are unique identifiers for each device that differentiate them on the network.

Public IP addresses

A public IP address is the primary address associated with your whole network. While each connected device has its own IP address, they are also included within the main IP address for your network. As described above, your public IP address is provided to your router by your ISP. Typically, ISPs have a large pool of IP addresses that they distribute to their customers. Your public IP address is the address that all the devices outside your internet network will use to recognize your network.

Public IP addresses

Public IP addresses come in two forms – dynamic and static.

Dynamic IP addresses

Dynamic IP addresses change automatically and regularly. ISPs buy a large pool of IP addresses and assign them automatically to their customers. Periodically, they re-assign them and put the older IP addresses back into the pool to be used for other customers. The rationale for this approach is to generate cost savings for the ISP. Automating the regular movement of IP addresses means they don’t have to carry out specific actions to re-establish a customer’s IP address if they move home, for example. There are security benefits, too, because a changing IP address makes it harder for criminals to hack into your network interface.

Static IP addresses

In contrast to dynamic IP addresses, static addresses remain consistent. Once the network assigns an IP address, it remains the same. Most individuals and businesses do not need a static IP address, but for businesses that plan to host their own server, it is crucial to have one. This is because a static IP address ensures that websites and email addresses tied to it will have a consistent IP address — vital if you want other devices to be able to find them consistently on the web.

 Internet domains

An Internet domain is a collection of data describing a self-contained administrative and technical unit on the Internet, according to the principles of the DNS system. This data can comprise the address of a computer, a resource or a service on the domain (www, e-mail, FTP), the name and address of the DNS server, security data for DNSSEC and more. Global visibility of an Internet domain is provided for by the DNS service.

An Internet domain name is a textual designation registered by a user for their own use, meeting administrative and technical conditions for the visibility of the Internet domain under that name. At the time of registration, the name is entered into the central registry database, which is administered by the Internet domain Registry. An Internet domain name becomes active once the registration data are entered, including data on the DNS servers, into the DNS table of the central registry database and that table is made active on public DNS servers. Internet domain names were traditionally written using the letters of the English alphabet (ASCII code), but with the development of the IDN standard the possibility has now been established for domain names to be written in other world languages and scripts. An Internet domain name is comprised of a series of alphanumeric segments, separated by full stops, complying with Internet standards. A segment can contain numbers (0-9), letters of the English (or some other) alphabet (a-z) and hyphens (-), and the length of a segment cannot be shorter than two or longer than 63 characters. A segment cannot contain a hyphen at the start or the end, or two consecutive hyphens as the third and fourth characters.

Domain name server

The Domain Name System (DNS) is the Internet’s system for mapping alphabetic names to numeric Internet Protocol (IP) addresses like a phone book maps a person’s name to a phone number. For example, when a Web address (URL) is typed into a browser, a DNS query is made to learn an IP address of a Web server associated with that name.

Using the www.example.com URL, example.com is the domain name, and www is the hostname. DNS resolution maps www.example.com into an IP address (such as When a user needs to load a webpage, a conversion must occur between what a user types into their web browser (www.example.com) into an IP address required to locate the www.example.com site.

The DNS system is an open worldwide network of database name servers that include 13 authoritative name servers that serve the DNS root zone level, known as “root servers”. A root server (also called a DNS root name server) receives a DNS query that includes a domain name (e.g. www.thousandeyes.com), and responds by directing that request to a top-level domain (TLD) nameserver, based on the TLD of that domain such as .com, .net, and .org. It directly responds to requests for DNS records in the root zone by returning an appropriate list of the authoritative TLD name servers for the appropriate TLD that can resolve the initial DNS lookup request for an IP address of that domain name.

TCP/IP protocols

TCP/IP stands for Transmission Control Protocol/Internet Protocol and is a suite of communication protocols used to interconnect network devices on the internet. TCP/IP is also used as a communications protocol in a private computer network (an intranet or extranet).

The entire IP suite — a set of rules and procedures — is commonly referred to as TCP/IP. TCP and IP are the two main protocols, though others are included in the suiteThe TCP/IP protocol suite functions as an abstraction layer between internet applications and the routing and switching fabric.

TCP/IP specifies how data is exchanged over the internet by providing end-to-end communications that identify how it should be broken into packets, addressed, transmitted, routed and received at the destination. TCP/IP requires little central management and is designed to make networks reliable with the ability to recover automatically from the failure of any device on the network.

The two main protocols in the IP suite serve specific functions. TCP defines how applications can create channels of communication across a network. It also manages how a message is assembled into smaller packets before they are then transmitted over the internet and reassembled in the right order at the destination address.

IP defines how to address and route each packet to make sure it reaches the right destination. Each gateway computer on the network checks this IP address to determine where to forward the message.

A subnet mask tells a computer, or other network device, what portion of the IP address is used to represent the network and what part is used to represent hosts, or other computers, on the network.

Network address translation (NAT) is the virtualization of IP addresses. NAT helps improve security and decrease the number of IP addresses an organization needs.

Common TCP/IP protocols include the following:

  • Hypertext Transfer Protocol (HTTP)handles the communication between a web server and a web browser.
  • HTTP Securehandles secure communication between a web server and a web browser.
  • File Transfer Protocolhandles transmission of files between computers.

How does TCP/IP work?

TCP/IP uses the client-server model of communication in which a user or machine (a client) is provided a service, like sending a webpage, by another computer (a server) in the network.

Collectively, the TCP/IP suite of protocols is classified as stateless, which means each client request is considered new because it is unrelated to previous requests. Being stateless frees up network paths so they can be used continuously.

The transport layer itself, however, is stateful. It transmits a single message, and its connection remains in place until all the packets in a message have been received and reassembled at the destination.

The TCP/IP model differs slightly from the seven-layer Open Systems Interconnection (OSI) networking model designed after it. The OSI reference model defines how applications can communicate over a network.

Why is TCP/IP important?

TCP/IP is nonproprietary and, as a result, is not controlled by any single company. Therefore, the IP suite can be modified easily. It is compatible with all operating systems (OSes), so it can communicate with any other system. The IP suite is also compatible with all types of computer hardware and networks.

TCP/IP is highly scalable and, as a routable protocol, can determine the most efficient path through the network. It is widely used in current internet architecture.

The 4 layers of the TCP/IP model

 TCP/IP functionality is divided into four layers, each of which includes specific protocols:

  1. The application layer provides applications with standardized data exchange. Its protocols include HTTP, FTP, Post Office Protocol 3Simple Mail Transfer Protocoland Simple Network Management Protocol. At the application layer, the payload is the actual application data.
  2. The transport layer is responsible for maintaining end-to-end communications across the network. TCP handles communications between hosts and provides flow control, multiplexing and reliability. The transport protocols include TCP and User Datagram Protocol, which is sometimes used instead of TCP for special purposes.
  3. The network layer, also called the internet layer, deals with packets and connects independent networks to transport the packets across network boundaries. The network layer protocols are IP and Internet Control Message Protocol, which is used for error reporting.
  4. The physical layer, also known as the network interface layer or data link layer, consists of protocols that operate only on a link — the network component that interconnects nodes or hosts in the network. The protocols in this lowest layer include Ethernet for local area networks and Address Resolution Protocol.

Uses of TCP/IP

TCP/IP can be used to provide remote login over the network for interactive file transfer to deliver email, to deliver WebPages over the network and to remotely access a server host’s file system. Most broadly, it is used to represent how information changes form as it travels over a network from the concrete physical layer to the abstract application layer. It details the basic protocols, or methods of communication, at each layer as information passes through.

Internet service providers

An Internet Service Provider (ISP) is the industry term for the company that is able to provide you with access to the Internet, typically from a computer. If you hear someone talking about the Internet and they mention their “provider,” they’re usually talking about their ISP.

Your ISP makes the Internet a possibility. In other words, you can have a shiny computer with a built-in modem and could have a router for networking, but without a subscription with an ISP, you won’t have a connection to the Internet.

For the typical homeowner or apartment dweller, the ISP is usually a “cable company” that, in addition, or offering a TV subscription, also offers an Internet subscription. You don’t get both for the price of one, however. You can get just cable TV or just high-speed Internet, or both.

An ISP is your gateway to the Internet and everything else you can do online. The second your connection is activated and set up, you’ll be able to send emails, go shopping, do research, and more. The ISP is the link or conduit between your computer and all the other “servers” on the Internet. You may feel like you’re talking to your mom directly through email, but in reality, it’s more “indirectly.” Your email goes from your computer to the ISP computers/servers, where it’s sent along to its destination through other servers on the network.


Intranet software may mean different things to different organizations, and even the unique teams and individuals within them, depending on that company’s objectives, sector, and structure. This means that sometimes, there can be confusion about what even constitutes an intranet.


Electronic mail (email or e-mail) is a method of exchanging messages (“mail”) between people using electronic devices. Email entered limited use in the 1960s, but users could only send to users of the same computer. Some systems also supported a form of instant messaging, where sender and receiver needed to be online simultaneously. Ray Tomlinson is credited as the inventor of networked email; in 1971, he developed the first system able to send mail between users on different hosts across the ARPANET, using the @ sign to link the user name with a destination server. By the mid-1970s, this was the form recognized as email.

Email operates across computer networks, primarily the Internet. Today’s email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need to connect, typically to a mail server or a webmail interface to send or receive messages or download it.


TELNET stands for TErminaL NETwork. It is a type of protocol that enables one computer to connect to local computer. It is a used as a standard TCP/IP protocol for virtual terminal service which is given by ISO. Computer which starts connection known as the local computer. Computer which is being connected to i.e. which accepts the connection known as remote computer. When the connection is established between local and remote computer. During telnet operation whatever that is being performed on the remote computer will be displayed by local computer. Telnet operates on client/server principle. Local computer uses telnet client program and the remote computers uses telnet server program.


The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and data connections between the client and the server.[1] FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. For secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS (FTPS) or replaced with SSH File Transfer Protocol (SFTP).

The first FTP client applications were command-line programs developed before operating systems had graphical user interfaces, and are still shipped with most WindowsUnix, and Linux operating systems.[2][3] Many FTP clients and automation utilities have since been developed for desktops, servers, mobile devices, and hardware, and FTP has been incorporated into productivity applications, such as HTML editors.


 IRC (Internet Relay Chat) is a protocol for real-time text messaging between internet-connected computers created in 1988. It is mainly used for group discussion in chat rooms called “channels” although it supports private messages between two users, data transfer, and various server-side and client-side commands. or example, OperaNet


Stands for “Network News Transfer Protocol.” NNTP is the protocol used to connect to Usenet servers and transfer newsgroup articles between systems over the Internet. It is similar to the SMTP protocol used for sending email messages, but is designed specifically for newsgroup articles.

Video conferencing

Video conferencing is a live video-based meeting between two or more people in different locations using video-enabled devices. Video conferencing allows multiple people to meet and collaborate face to face long distance by transmitting audio, video, text and presentations in real time through the internet.


E-commerce (electronic commerce) is the buying and selling of goods and services, or the transmitting of funds or data, over an electronic network, primarily the internet. These business transactions occur either as business-to-business (B2B), business-to-consumer (B2C), consumer-to-consumer or consumer-to-business.

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