Computer Networking Full Course - Internet Explained Step by Step (Real-Life Examples)

TLDR;

This video provides a comprehensive guide to computer networks and how the internet works. It covers essential topics such as the basics of computer networking, the history of the internet, data transfer methods, IP addresses, network types, network topologies, the OSI model, client-server architecture, and internet protocols.

• The internet is a connection between computers and electronic devices that allows data transfer following specific rules.
• The history of the internet began with the Cold War and the need for decentralised data storage.
• Data is transferred in packets, with headers containing IP addresses and other metadata.
• IP addresses identify devices on a network, and port numbers specify which applications are used.
• Network topologies describe the layout of connections between devices, each with advantages and disadvantages.
• The OSI model provides a conceptual framework for understanding how data is transmitted across networks.
• Client-server architecture involves clients requesting services from servers, while peer-to-peer architecture allows direct communication between devices.
• Internet protocols are sets of rules that govern how data is transmitted and received over the internet.

Introduction [1:28]

The video aims to provide a detailed understanding of how the internet works, using computer networks and real examples. It is designed for both beginners and those seeking a deeper understanding of the topic, covering college exam preparation, placement preparation, and general knowledge. The presenter encourages viewers to watch the video multiple times, take notes, and master each topic.

Syllabus Overview [5:24]

The video will cover several key topics, starting with how the internet works, followed by the history of the internet, including the roles of the Cold War, the USA, and figures like Tim Berners-Lee. It will also explain how data is transferred via optical cables, the role of the cloud, and the use of protocols like TCP/IP. Further topics include IP addresses, port numbers, types of networks (LAN, MAN, WAN), network topologies (bus, mesh), the OSI model, client-server architecture, and various internet protocols.

How the Internet Works [10:32]

The internet is defined as a connection between computers and electronic devices that enables data transfer, governed by a set of rules. It is a worldwide system of interconnected computer networks and electronic devices that communicate using established protocols. Data is transferred in packets, each with a header containing the sender's and receiver's IP addresses. Protocols like TCP ensure reliable data delivery, while UDP offers faster transmission without guaranteed delivery.

History of the Internet [22:42]

The history of the internet begins after World War II, during the Cold War between the USA and Russia. The USA created the Advanced Research Projects Agency (ARPA) to decentralise data and prevent data loss from potential nuclear attacks. ARPA evolved into the Defense Advanced Research Projects Agency (DARPA), which tasked universities with developing the internet. In 1969, the University of California, Los Angeles (UCLA) sent the first message, "LO," to Stanford University, marking the beginning of the internet. Later, Vint Cerf and Bob Kahn developed the TCP/IP protocol in 1983, and Tim Berners-Lee created the World Wide Web (WWW), HTTP, and HTML in 1990, making the internet accessible to everyone.

How Data is Transferred Over the Internet [41:32]

Data transfer involves several steps, starting with a message sent via an application like WhatsApp. The message is encrypted and broken into packets, each with sender and receiver IP addresses. The phone connects to the internet via 4G/5G or Wi-Fi, with Wi-Fi using 2.4 GHz or 5 GHz frequencies. The data reaches a Wi-Fi router, which assigns a local IP address and port number. The router applies Network Address Translation (NAT) to convert the private IP address to a public IP address. The data then goes to the Internet Service Provider (ISP), which finds the shortest path to the destination, often using submarine optical fibre cables. The data reaches the WhatsApp server, which checks if the recipient is online and forwards the message or stores it for later delivery.

IP Address and Port Number Explained [56:51]

An IP address is a device's address on the internet, with two main versions: IPv4 (32-bit) and IPv6 (128-bit). IPv4 is limited to 4.3 billion addresses, while IPv6 offers significantly more. A port number identifies which application on a device is sending or receiving data, with 65,535 ports available. Ports 0-1023 are well-known or system ports, while others are used by applications. The Domain Name System (DNS) translates domain names (e.g., shars.com) into IP addresses, making it easier to remember and access websites.

Types of Networks (6 Types) [1:07:37]

There are several types of networks, including:

1. Personal Area Network (PAN): Short-range networks like Bluetooth connections between a phone and earbuds.
2. Local Area Network (LAN): Networks in a small area, such as a home, school, or office, using Wi-Fi.
3. Metropolitan Area Network (MAN): City-based networks, like cable services.
4. Wide Area Network (WAN): Country-wide networks, such as the internet or bank branches across a country.
5. Campus Area Network (CAN): Networks connecting multiple buildings in a campus, like a college.
6. Virtual Private Network (VPN): Encrypted networks that allow users to change their IP address and location.

Network Topology Explained [1:24:58]

Network topology describes how devices are connected in a network. Common topologies include:

1. Bus Topology: Devices connected to a single backbone cable, which is cost-effective but vulnerable to cable failure.
2. Ring Topology: Devices connected in a ring, offering fast data transfer but susceptible to network disruption if one device fails.
3. Star Topology: Devices connected to a central hub, which is easy to manage but dependent on the hub's reliability.
4. Mesh Topology: Devices interconnected with each other, providing high reliability and speed but high cost.
5. Tree Topology: A combination of star and bus topologies, suitable for large organisations with multiple sections.
6. Hybrid Topology: A combination of multiple topologies, offering flexibility but complexity.

OSI Model and Its Layers [2:04:05]

The OSI (Open Systems Interconnection) model is a conceptual framework that standardises how data is transmitted between systems. It consists of seven layers:

1. Application Layer: Interacts with the user and applications, using protocols like HTTP, SMTP, and FTP.
2. Presentation Layer: Translates, compresses, and encrypts data to ensure compatibility and security.
3. Session Layer: Creates and manages sessions between applications, ensuring reliable data transfer with checkpoints.
4. Transport Layer: Segments data into packets, sequences them, and ensures reliable delivery using TCP or UDP.
5. Network Layer: Assigns IP addresses and routes data to its destination using protocols like IP and RIP.
6. Data Link Layer: Ensures reliable data transfer between two directly connected nodes, using MAC addresses.
7. Physical Layer: Transmits raw data as bits over a physical medium, such as wires or radio waves.

Client-Server Architecture [2:16:19]

Client-server architecture involves clients requesting services from servers. Clients send requests, and servers respond with the requested data or service. Servers are computers programmed to accept requests and send back responses. Peer-to-peer architecture, on the other hand, allows direct communication between devices without a central server. Each device acts as both a client and a server, sharing resources and data.

Internet Protocols Explained [2:36:59]

Internet protocols are sets of rules that govern how devices communicate over the internet. They define how data is transmitted, received, and verified. Key protocols include:

• HTTP/HTTPS: Application layer protocols for web browsing, with HTTPS providing secure communication.
• IP (Internet Protocol): Network layer protocol for addressing and routing data packets.
• TCP (Transmission Control Protocol): Transport layer protocol that ensures reliable, ordered delivery of data.
• UDP (User Datagram Protocol): Transport layer protocol that provides fast, connectionless data transfer without guaranteed delivery.