What happens when you type google.com in your browser and press Enter
Introduction:
When we enter a website address like "https://www.google.com" into our web browser, a series of processes take place to deliver the requested web page. These processes involve various systems and protocols. In this explanation, we will explore the step-by-step journey of a web request and explain the roles of DNS, TCP/IP, firewalls, HTTPS/SSL, load balancers, web servers, application servers, and databases.
When you type a URL (https://www.google.com) into your browser, it needs to understand the request. However, computers don't understand English directly, so the browser extracts the domain name (google.com) and checks its cache, and storage for quick retrieval of previous information. Since it's your first time, the browser doesn't find the information there. It then sends the domain name to a DNS (Domain Name System) server through your Internet Service Provider (ISP). The DNS server translates the domain name into an IP address, which helps the browser locate the server hosting the website you want to visit.
This translation is necessary because computers communicate more effectively using numbers (IP addresses) than words. To establish a connection with the desired website, the browser needs the IP address, which is a unique numerical identifier. However, humans find it difficult to remember websites by numbers, so we attach words (domain names) to these numerical addresses.
TCP/IP:
The TCP/IP (Transmission Control Protocol/Internet Protocol) is a vital part of the communication process on the Internet. It encompasses a set of rules known as network protocols, which govern how data is formatted, transmitted, and received. These protocols enable effective communication between devices on a computer network, regardless of their infrastructure, design, or standards.
TCP (Transmission Control Protocol) handles the exchange of messages between different points on the internet at the packet level. It ensures that messages are properly divided into packets, transmitted over the internet, and reassembled accurately at the destination.
IP (Internet Protocol) focuses on addressing and routing these packets for delivery. It assigns unique IP addresses to devices and manages the routing of packets across the network.
The TCP/IP suite consists of four layers:
1. Application layer: This topmost layer provides users with access to network resources and services. It includes protocols like HTTP (Hypertext Transfer Protocol), SMTP (Simple Mail Transfer Protocol), SNMP (Simple Network Management Protocol), and FTP (File Transfer Protocol).
2. Transport layer: This layer ensures the reliable transmission of data segments over the network. It establishes a connection between the source and destination systems.
3. Internet layer: Also known as the network layer, it handles the sending and receiving of packets within the network. It involves protocols such as IP, ARP (Address Resolution Protocol), and ICMP (Internet Control Message Protocol).
4. Network access layer: This layer combines the physical and data-link layers of the OSI model (a reference model for network protocols). Further details about this layer go beyond the scope of this explanation.
Firewall:
The term "firewall" originated from its original use as a physical barrier against fires and later extended to computer networking. In the context of technology, firewalls serve as protective measures to control network traffic.
Initially, firewalls were physical hardware devices that regulated network access, allowing authorized data while blocking unauthorized traffic. A firewall's policy defines rules for permitting or denying network traffic.
In computer networking, a firewall acts as a protective barrier between a private network and the Internet. It can be implemented using hardware or software. Firewalls analyze data packets seeking network access and apply predefined rules to allow, restrict, or block specific traffic. They also facilitate secure remote access to private networks through authentication certificates and logins.
HTTPS/SSL:
HTTPS (Hyper Text Transfer Protocol Secure) is the secure version of HTTP, the protocol used for transmitting data between your web browser and the website you're visiting. It ensures that all communication between your browser and the website is encrypted. HTTPS is commonly used to protect sensitive online transactions like banking and shopping.
Web browsers display a padlock icon in the address bar to indicate when an HTTPS connection is active.
Originally, network administrators needed a way to share information on the Internet, so they established the HyperText Transfer Protocol (HTTP). However, regular HTTP connections transmit data in plain text, making them vulnerable to interception by hackers. This is especially risky when sharing sensitive information like credit card details.
To protect data, administrators introduced SSL (Secure Sockets Layer) certificates for encrypting online information. This led to the development of HTTPS, where data is encrypted using a shared "code" between the sender and recipient. Even if someone intercepts the message, they cannot understand it without the "code."
Computers use SSL certificates containing character strings as encryption keys. These certificates include a public key for encrypting messages to the computer owner, while the private key, essential for decryption, remains confidential.
During data transfer, security is ensured through the Secure Sockets Layer (SSL) and Transport Layer Security (TLS). When a website supports secure communication (indicated by "https" in the URL), an SSL/TLS handshake occurs between the browser and server. This handshake establishes an encrypted connection, ensuring data privacy and integrity during transmission.
Load Balancer:
Websites like Facebook, Linkedin, and Twitter handle enormous traffic by using multiple servers instead of relying on a single one. To distribute incoming web traffic among these servers, load balancers are used.
A load balancer's role is to distribute the workload of a system among multiple servers or groups of servers. This reduces the burden on individual servers, leading to improved reliability, efficiency, and availability of the website or application.
Two types of load balancers employ different scheduling algorithms and routing mechanisms, but discussing them in detail is beyond the scope of this explanation.
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In the case of high-traffic websites like Google, a load balancer plays a crucial role. It evenly distributes incoming requests across multiple servers, optimizing performance and preventing any server from becoming overwhelmed. The load balancer considers factors like server capacity, response time, and current load to determine the best server for each request. This ensures efficient and reliable delivery of web content to users.
Web Server:
A web server is a software that delivers web pages to users. It can run on a physical computer or in the cloud as a virtual machine or container.
On the hardware side, a web server refers to a computer that stores web server software and website files such as HTML, images, CSS, and JavaScript. It is connected to the internet and facilitates data exchange with other devices.
The software components of a web server control how users access hosted files. It includes an HTTP server, which understands web addresses (URLs) and the HTTP protocol used by web browsers. The web server can be accessed through domain names and delivers website content to users' devices.
When a browser requests a file from the web server, it sends an HTTP request. The HTTP server on the web server receives the request, locates the requested document, and sends it back to the browser through HTTP. If the requested document is not found, the server returns a 404 response.
Application Server:
An application server serves as a platform for client application programs to access and utilize business logic. It allows client applications to invoke methods provided by the application server, similar to calling methods on an object.
Clients of an application server can include graphical user interfaces (GUIs) on PCs, web servers, or other application servers. Unlike a web server that primarily handles static HTML, communication between an application server and its clients involves exchanging program logic rather than simple display markup. This enables clients to leverage the exposed business logic in different ways.
Database:
A database is a structured collection of electronically stored information, managed by specialized software called a database management system (DBMS). It consists of tables with rows and columns, organizing data in a structured format for efficient processing and querying.
Databases allow for easy access, management, modification, updating, control, and organization of information. They use a standardized language called structured query language (SQL) for writing and querying data, providing a common way to interact with the database and perform operations.
Operations such as retrieving specific data, inserting new data, updating existing data, and deleting data.
Conclusion:
The journey of a web request from typing a URL to receiving a web page involves multiple layers of infrastructure and technologies working seamlessly. DNS resolution maps the domain name to an IP address, TCP/IP establishes a connection, firewalls provide security checks, HTTPS/SSL ensures encrypted communication, load balancers optimize traffic distribution, web servers handle incoming requests, application servers process dynamic content, and databases store and retrieve data. Each component plays a crucial role in delivering a seamless web browsing experience.
The collaborative efforts of these systems enable us to access and interact with websites effortlessly. As technology advances, we can expect further enhancements to improve our browsing experience and ensure a secure online environment.
Next time you enter a URL, take a moment to acknowledge the intricate journey your request undertakes, connecting you to a vast world of information and experiences. Enjoy your browsing!
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