Behind the Scenes: A Technical Overview of How Browsers Access Websites

In the digital age, we take for granted the ability to access any website at the click of a button. However, behind the scenes, a complex series of events takes place in order to display the requested web page. From DNS requests to load balancing, each step in the process plays a crucial role in ensuring that the user receives the web page quickly and securely. In this article, we will take a deep dive into the technical details of how browsers access websites, providing a comprehensive overview of the complex web stack on top of the internet. Whether you're a software engineer looking to optimize web applications or simply curious about how the internet works, this article is for you. So, buckle up and join us as we journey behind the scenes of web browsing.

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DNS Request

The first step in accessing any website is to translate the human-readable URL into an IP address. A human-readable domain names like (www.google.com) into IP addresses like (216.58.223.196) that computers can understand. The Domain Name System (DNS) is responsible for performing this translation. The DNS server maintains a database of all the IP addresses associated with a domain name. When you enter the URL, your browser sends a DNS request to your local DNS resolver, which checks its cache for the IP address associated with the domain name. If the IP address is not cached, the resolver sends a query to the DNS server to retrieve the IP address.

For example, when you type "google.com" in your browser, your browser sends a DNS request to your local DNS resolver. If the IP address is not cached, the resolver sends a query to the DNS server to retrieve the IP address associated with "google.com". The DNS server responds with the IP address, and the browser uses this IP address to establish a TCP connection with the web server.

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TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is a set of protocols used to facilitate communication between devices on the internet. Once the browser has the IP address, it initiates a Transmission Control Protocol (TCP) connection with the web server. TCP is a reliable protocol that establishes a connection between two devices and ensures that data is transmitted without errors or loss. In other words, TCP is responsible for breaking data into packets and reassembling them at the receiving end, while IP is responsible for routing the packets to their destination.

For example, when you type "https://www.google.com" in your browser, the browser initiates a TCP connection with the IP address of the web server associated with Google's domain name. The browser and web server exchange packets of data over this connection, which includes the HTTP request from the browser and the HTTP response from the server.

Similarly, when you send an email to someone across the internet, your email client uses TCP/IP to break the message into packets and send them across the network to the recipient's email server. The recipient's email server then uses TCP/IP to reassemble the packets and deliver the message to the recipient's inbox.

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Firewall

Before the connection is established, the request passes through a firewall, which is designed to protect the network from unauthorized access. The firewall examines the request and decides whether to allow or block it based on pre-defined security rules. A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on a set of predefined security rules. Firewalls can be either hardware or software-based, and they can be used to protect individual devices or entire networks.

For example, suppose you work for a company that has a firewall in place to protect its internal network. If you try to access a website that is not allowed by the firewall, the firewall will block the request and prevent you from accessing the website. Also, a home or particular internet user might use a firewall to block incoming traffic from unknown sources or to restrict access to certain devices on their home network.

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HTTPS/SSL

Once the connection is established, the browser and web server negotiate a Secure Sockets Layer (SSL) or Transport Layer Security (TLS) encryption protocol. HTTPS (Hypertext Transfer Protocol Secure) is a protocol used to secure communication over the internet. HTTPS uses SSL (Secure Sockets Layer) or its successor, TLS (Transport Layer Security), to encrypt data sent between a web browser and a web server, protecting it from interception by attackers. This protocol ensures that the communication between the browser and the web server is encrypted and secure. The SSL/TLS protocol involves a series of steps, including verifying the server's identity, exchanging encryption keys, and establishing a secure connection.

For example, when you type "https://www.google.com" in your browser, the browser and web server negotiate an SSL/TLS encryption protocol. The SSL/TLS protocol ensures that the communication between the browser and the web server is encrypted and secure, protecting sensitive data such as login credentials, credit card numbers, and personal information.

Similarly, when you log into your bank's website, the website uses HTTPS to encrypt your login credentials as they are sent from your browser to the bank's servers. This prevents attackers from intercepting your credentials and gaining access to your account.

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Load-Balancer

In some cases, the web server may be behind a load balancer, which distributes incoming traffic across multiple web servers to improve performance and availability. A load-balancer is a network device or software application that distributes incoming network traffic across multiple servers in order to improve performance, reliability, and scalability. Load-balancers can be either hardware or software-based, and they can be used to manage traffic to individual services or entire applications. The load balancer receives the request from the browser and forwards it to one of the available web servers.

For example, suppose you are trying to access a website that has high traffic. In this case, the website may use a load balancer to distribute incoming traffic across multiple web servers to improve performance and availability. The load balancer receives the request from your browser and forwards it to one of the available web servers.

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Web Server

Let me quickly explain what a web server is and its behavior. A web server is a computer program that is responsible for handling HTTP requests and responses. It delivers web pages, images, videos, and other files to a client (usually a web browser) over the internet. Web servers are typically divided into two categories: static and dynamic.

A static web server delivers pre-written HTML pages to the client. These pages are stored on the server's file system and are served directly to the client upon request. Static web servers are simple, fast, and efficient, but they cannot generate content dynamically based on user input or other data.

A dynamic web server, on the other hand, uses a combination of server-side scripting, database technology, and client-side code to generate content on the fly. These servers are capable of generating custom web pages based on user input, user preferences, or other data. Examples of dynamic web servers include Apache, Nginx, and Microsoft IIS.

When a request is received, the web server returns the requested content (typically a web page or file) to the browser. Web servers typically use HTTP (Hypertext Transfer Protocol) or HTTPS to communicate with web browsers. The web server retrieves the requested web page and sends it back to the browser in a series of packets. The response may include HTML, CSS, JavaScript, images, or other resources required to render the web page.

For example, when you type "https://www.google.com" in your browser, the request reaches the web server associated with Google's IP address. The web server retrieves the requested web page.

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Application Server

An application server is a type of server designed to install, run, and maintain software applications. It provides an environment where applications can run, interact with other applications, and communicate with the database server. It acts as a middleware between the client and the database server. The application server manages the application's business logic and processing, and can handle multiple client requests simultaneously.

If the web page requires dynamic content, such as user-specific data or real-time information, the request is forwarded to an application server. The application server processes the request and generates a response, which is sent back to the web server for inclusion in the final response.

In other to understand it better, an application server is a software framework that is responsible for executing code and managing data on behalf of an application. It provides an environment for web applications to run, including a runtime engine, libraries, and APIs for developers to use.

Application servers are typically used for complex web applications that require dynamic content, scalability, and reliability. They provide a platform for developers to build and deploy web applications quickly and easily. Some examples of application servers include Apache Tomcat, IBM WebSphere, Oracle WebLogic, Tomcat, JBoss etc.

For instance, let's consider an e-commerce website where customers can buy products online. The application server handles all the business logic such as processing customer orders, tracking inventory, and updating the database with transaction details. It also interacts with the web server to provide the user interface for the customer. When a customer selects a product, the application server retrieves the product details from the database and displays them to the customer. Once the customer places the order, the application server updates the database with the order details and sends a confirmation email to the customer.

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Database

If the application server needs to retrieve or store data, it communicates with a database server. The database server stores and retrieves data requested by the application server.

A database is a software program that stores, organizes, and manages data. It is an essential component of many web applications because it allows applications to store and retrieve information quickly and efficiently. Databases can be classified into two main categories: relational and non-relational.

Relational databases use a structured query language (SQL) to interact with data. They store data in tables that are organized into rows and columns. Each table represents a different entity, such as customers, orders, or products. Examples of relational databases include MySQL, Oracle, and Microsoft SQL Server.

Non-relational databases, also known as NoSQL databases, are designed to handle large volumes of unstructured data. They do not use SQL and do not store data in tables. Instead, they store data in a variety of formats, including key-value stores, document databases, and graph databases. Examples of NoSQL databases include MongoDB, Cassandra, and Couchbase.

For instance, let's consider a banking application where customers can view their account details and perform transactions. The database stores all the customer account information, including their account balance, transaction history, and personal details. When a customer logs into the banking application, the application server retrieves the customer's account details from the database and displays them to the customer. When the customer performs a transaction, the application server updates the database with the transaction details, and the customer's account balance is adjusted accordingly. The database also stores transaction history, which can be used for generating reports and analytics.

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In conclusion, typing https://www.google.com or any other URL in your browser and pressing enter initiates a complex process that involves multiple components and technologies working together. From the initial DNS request to the final database query, each step is critical for delivering fast, reliable, and secure web experiences to users.

Understanding how these components work together is essential for web developers, network administrators, and other IT professionals. It enables them to build and maintain robust web applications that can handle high volumes of traffic, provide dynamic content, and ensure data security and privacy.

In today's digital age, web applications are more critical than ever before, and their importance will continue to grow as businesses and individuals rely more heavily on the internet for communication, commerce, and entertainment. Therefore, it is crucial to have a solid understanding of the web stack and its various components.

In summary, by understanding how these components work together, we can build and maintain web applications that provide fast, reliable, and secure experiences for users around the world.

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