Lecture 1: Introduction To Web Development | Internet Working |

1. What is the Internet?

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The Internet is a global network of interconnected computers and devices that allows users to access and share information and devices, allowing them to communicate and exchange data. It enables users to access a wide range of services, such as websites, emails, social media, online applications, and cloud storage. Through standardized communication protocols, the Internet facilitates the sharing of information, resources, and media across vast distances, making it an essential tool for worldwide:
Education
Business
Entertainment
Personal Communication

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2. How is data transferred?

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Data is transferred by breaking it into small, addressable packets, which are then sent through a network via wired (like fiber optic cables) or wireless (like Wi-Fi) channels. Protocols such as TCP/IP govern this process, directing the packets using devices like routers to their destination, where they are reassembled into the original information. The speed and accuracy of this transfer depend on factors like bandwidth, network congestion, and the use of appropriate hardware and communication standards

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3. What is IP Address?

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An IP address (Internet Protocol address) is a unique numerical label assigned to every device on a network, like the internet, that enables communication and data routing. It functions similarly to a postal address, allowing data packets to be sent and received by the correct destination on a network. There are two main versions, IPv4 and IPv6, with IPv6 offering a significantly larger address space to accommodate the growing number of internet-connected devices.

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4. How to access a website?

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Computers and their systems are difficult to approach, and it's made even more difficult when you need to understand two terms related to the subject that is already used in everyday English, Network, and internet will seem to be completely distinct from one another, but they will appear to be identical.
A network is a collection of one or more computers (Multiple devices, also known as hosts), that are connected via multiple channels for the purpose of sending and receiving data or media in a shared environment. The network can also include numerous devices/mediums that aid communication between two or more machines; these devices are known as Network devices and include routers, switches, hubs, and bridges, among others.
Internet is a collection of computers connected from all over the world. The Internet protocol suite is a framework described by the Internet standards. Methods are divided into a layered set of protocols in this architecture. The Internet offers a wide range of information and communication services, including forums, databases, email, and hypertext. It is made up of local to worldwide private, public networks linked by a variety of electronic, wireless, and networking technologies.

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5. Who assigns the IP Address?

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IP addresses are assigned hierarchically, beginning with the Internet Assigned Numbers Authority (IANA), which allocates blocks of addresses to Regional Internet Registries (RIRs) like APNIC or RIPE NCC. These RIRs then assign large blocks to Internet Service Providers (ISPs) and large organizations. Finally, your ISP assigns a public IP address to your router, and your router, acting as a DHCP server, assigns a private (local) IP address to each device within your home or office network.

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6. Concept of DNS

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The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.
Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6).

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7. How does DNS work?

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The process of DNS resolution involves converting a hostname (such as www.example.com) into a computer-friendly IP address (such as 192.168.1.1). An IP address is given to each device on the Internet, and that address is necessary to find the appropriate Internet device - like a street address is used to find a particular home. When a user wants to load a webpage, a translation must occur between what a user types into their web browser (example.com) and the machine-friendly address necessary to locate the example.com webpage.
In order to understand the process behind the DNS resolution, it’s important to learn about the different hardware components a DNS query must pass between. For the web browser, the DNS lookup occurs "behind the scenes" and requires no interaction from the user’s computer apart from the initial request.

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8. Problems in Data Transfer and MAC Address

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Problems in data transfer related to MAC addresses include network access issues due to spoofing, lack of scalability for internet-wide communication, hardware dependency causing changes with new network cards, and security vulnerabilities from plain-text transmission. Proper MAC address management is critical for local network security and device identification, while IP addresses are used for broader internet routing

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9. What is Port Numbers?

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Port numbers are numerical identifiers (0-65535) that act as endpoints for network communication, directing traffic to specific applications or services on a device, similar to how an apartment number directs mail to a specific resident within a building. When a device receives data, the port number in the data packet, along with the IP address, specifies which program or service on that device should process the information, ensuring that different applications, like web browsing (port 80) or email (port 25), can run simultaneously without confusion.

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10. IPv4 and IPv6

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IPv4 and IPv6 are versions of the Internet Protocol (IP) that assign unique addresses to devices on a network, with IPv6 being the newer version designed to replace the limited address space of IPv4. The primary differences lie in address length (IPv4 uses 32-bit addresses, IPv6 uses 128-bit), addressing format (IPv4 uses dotted-decimal notation, IPv6 uses hexadecimal groups), and features like improved routing efficiency, built-in security, and Quality of Service (QoS) in IPv6

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11. MAC Address Format

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To understand what is MAC address is, it is very important that first you understand the format of the MAC Address. So a MAC Address is a 12-digit hexadecimal number (48-bit binary number), which is mostly represented by Colon-Hexadecimal notation.
The First 6 digits (say 00:40:96) of the MAC Address identify the manufacturer, called the OUI (Organizational Unique Identifier). IEEE Registration Authority Committee assigns these MAC prefixes to its registered vendors.
Here are some OUI of well-known manufacturers:
CC:46:D6 - Cisco
3C:5A:B4 - Google, 3C:D9:2B - Hewlett Packard
00:9A:CD - HUAWEI TECHNOLOGIES CO.,LTD

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12. Port Number Format

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A "port number format" depends on its purpose, but for mobile number portability, it is the text "PORT" followed by a space and your 10-digit mobile number, sent as an SMS to 1900. In contrast, a network port number format is a two-byte, 16-bit integer ranging from 0 to 65535, where a specific number represents a service like port 80 for HTTP.

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13. Local Area Network, Switch & Router

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A Local Area Network (LAN) is a small, private network connecting devices like computers and printers within a limited area, such as a home or office. A network switch connects multiple devices within a single LAN, using MAC addresses to send data directly to the intended device. A router connects a LAN to other networks or the internet, using IP addresses to intelligently route data packets across different networks

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14. Public and Private Addresses

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Public IP addresses are unique, globally identifiable IP addresses provided by an ISP and used for internet-wide communication. Private IP addresses are used within a local network (like a home or office) and are not directly accessible from the internet, with the same private IP address being reusable across many different local networks. A router uses Network Address Translation (NAT) to allow devices with private IP addresses to access the internet by substituting their private IP with the router's public IP.

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15. Modern Routers

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A modern router is a networking device that connects multiple networks, such as your home Local Area Network (LAN) to the wider Internet (WAN), by forwarding data packets to their correct IP addresses. Beyond simply sending data, modern routers also provide advanced features like Wi-Fi connectivity, security protocols, simplified mobile app-based management, and even integrated modem functionality for easier internet access

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16. What is a VPN?

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A VPN (Virtual Private Network) is an internet security service that creates a secure, encrypted "tunnel" for your online traffic, hiding your real IP address and location to protect your privacy and data. It works by routing your internet connection through a remote VPN server, encrypting your data along the way, which makes it difficult for others to track your activities, steal information, or bypass geo-restrictions

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17. What is Web Development?

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Web development is the process of creating and maintaining websites and web applications that run online, encompassing tasks from designing the user interface to coding functionality and managing databases. It involves various aspects such as front-end development (what users see and interact with) and back-end development (the server, database, and application logic), and uses coding languages like HTML, CSS, and JavaScript to bring designs to life and ensure smooth performance.

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18. What is the MERN Stack?

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The MERN stack is a collection of four open-source JavaScript technologies—MongoDB, Express.js, React, and Node.js—used by developers to build complete, dynamic, and scalable web applications from the frontend to the backend. It offers a full-stack JavaScript development experience, allowing for efficient data handling and robust, user-friendly interfaces.

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19. Who is a Full-Stack Developer?

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A full stack developer is a software developer who can handle all aspects of an application's development, from the user interface (front-end) to the server-side logic and databases (back-end). They are versatile professionals with a wide range of skills, including front-end technologies like HTML, CSS, and JavaScript, back-end languages such as Python or Node.js, various database systems, and essential development tools like Git. This holistic understanding allows them to manage the entire development process, from conceptualization to deployment and maintenance.

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