WHAT HAPPENS WHEN YOU TYPE GOOGLE.COM INTO YOUR BROWSER AND PRESS ENTER
Published: 2023-05-11 20:51:21

When you type "google.com" in your browser and press enter, a series of complex processes occur behind the scenes to display the Google homepage on your screen.
Here's a more detailed breakdown of what happens:

**1. DNS REQUEST:**
When you enter "google.com" into your browser, the first step in the process is a DNS request. DNS stands for Domain Name System, and it is responsible for translating human-readable domain names, such as "google.com," into IP addresses that computers can understand. The DNS request is sent from your computer to a DNS server, which then queries other DNS servers to find the IP address associated with the domain name. The DNS server then sends the IP address back to your computer, which uses it to establish a connection with the server hosting the website.

**2. TCP/IP:**
Once your computer has obtained the IP address for the Google server, it establishes a connection using TCP/IP. TCP (Transmission Control Protocol) is responsible for breaking the data into small packets, ensuring that they are sent in the correct order, and retransmitting any lost packets. IP (Internet Protocol) is responsible for routing the packets across the internet to their final destination. Together, TCP/IP provides a reliable, end-to-end connection between your computer and the Google server.

**3. FIREWALL:**
A firewall is a network security device that monitors and controls incoming and outgoing network traffic. It acts as a barrier between your computer and the internet, allowing only authorized traffic to pass through. Firewalls can be hardware or software-based and are configured with a set of rules that determine which types of traffic are allowed or blocked. Firewalls are an essential part of any network security strategy and help protect against a range of cyber threats, including malware, hackers, and denial-of-service attacks.

**4. HTTPS/SSL:**
When your browser connects to the Google server, it uses HTTPS (Hypertext Transfer Protocol Secure) to ensure that the data transmitted between your computer and the server is encrypted and secure. HTTPS uses SSL/TLS (Secure Sockets Layer/Transport Layer Security) to establish a secure connection. SSL/TLS uses a combination of encryption algorithms, public and private keys, and digital certificates to protect data and verify the identity of the server. By using HTTPS/SSL, Google can protect sensitive information, such as login credentials and credit card information, from being intercepted by third parties.

**5. LOAD BALANCER:**
A load-balancer is a device that distributes incoming network traffic across multiple servers to improve performance and prevent overload. Load-balancers can balance traffic based on a variety of factors, including server availability, response time, load, and geographic location. By distributing traffic across multiple servers, load-balancers can help ensure that web applications remain available and responsive, even during high traffic periods.

**6. WEB SERVER:**
Once your computer has established a connection with the Google server, the web server processes your request and sends the response back to your computer. A web server is software that runs on a server and delivers web content to clients over the internet. Web servers can deliver a range of content, including HTML, CSS, JavaScript, images, and other resources. The web server retrieves the necessary files and data to generate the webpage, processes any dynamic content, and sends the response back to your browser.

**7. APPLICATION SERVER:**
In some cases, the web server may send the request to an application server. An application server is software that provides an environment for running web applications. Application servers can execute code written in various programming languages, such as Java, Python, Ruby, or PHP. The application server processes the request, retrieves data from a database if necessary, and generates a response, which is then sent back to the web server for delivery to your browser.

**8. DATABASE:**
Finally, if the web application requires data to be retrieved or stored, it may send a request to a database server. A database server is a software application or collection of data that is organized in a way that allows easy retrieval and manipulation. When an application needs to retrieve or store data, it sends a request to a database server. The database server then retrieves the data from the database and sends it back to the application server for processing. Databases can be relational or non-relational, depending on the data model used.

In conclusion, when you type "google.com" in your browser and press enter, a complex sequence of events occurs, involving DNS request, TCP/IP, firewall, HTTPS/SSL, load-balancer, web server, application server, and database. These processes work together seamlessly to deliver the Google homepage to your screen in a matter of seconds, enabling you to access the vast resources of the internet with ease.

The above components of a server request are broken down in full detail below:


<u>1. DNS Request:</u>
DNS (Domain Name System) is a distributed database system that translates human-readable domain names (like google.com) into IP addresses that computers can understand. When you type a domain name in your browser, your computer sends a DNS request to a DNS server, which looks up the IP address associated with that domain name. The DNS server then returns the IP address to your computer, allowing it to establish a connection with the appropriate server.

The Domain Name System (DNS) is a hierarchical naming system that translates human-readable domain names into IP addresses. It plays a crucial role in facilitating internet communication by providing a distributed database that maps domain names to their corresponding IP addresses. Let's explore the different types of DNS servers in more detail:

Root DNS Servers:
At the top of the DNS hierarchy are the Root DNS servers. They are the starting point for any DNS resolution process. There are 13 sets of root servers worldwide, identified by letters from A to M. These servers store the IP addresses of the authoritative DNS servers responsible for top-level domains (TLDs). When a DNS resolver receives a query for a domain name, it contacts a root DNS server to obtain information about the appropriate TLD server.

Top-Level Domain (TLD) DNS Servers:
Top-Level Domain DNS servers are responsible for managing specific top-level domains, such as .com, .org, .net, and country-code TLDs like .uk, .fr, and .jp. Each TLD has its own set of DNS servers, which store information about the second-level domain names within that TLD. For example, the .com TLD DNS servers maintain information about domain names ending with .com.

Authoritative DNS Servers:
Authoritative DNS servers are responsible for storing and providing the actual DNS records for a particular domain. There are multiple levels of authoritative DNS servers, depending on the hierarchy of the domain name. For example, if you query for "www.example.com," the authoritative DNS server for the "com" TLD will be contacted by the resolver. The TLD server will then provide the IP address or the next level of authoritative DNS servers responsible for the "example.com" domain. This process continues until the IP address associated with "www.example.com" is obtained.

Caching DNS Servers:
Caching DNS servers, also known as recursive DNS servers, are typically operated by Internet Service Providers (ISPs) or organizations. These servers help improve DNS resolution performance by caching the DNS records they receive. When a resolver receives a query, it checks its cache first to see if it has the corresponding IP address. If not, it recursively queries the appropriate DNS servers to obtain the information and stores it in its cache for future use.

Forwarding DNS Servers:
Forwarding DNS servers act as intermediaries between resolvers and other DNS servers. Instead of resolving queries themselves, these servers forward the queries to other DNS servers, such as ISP's DNS servers or public DNS resolvers like Google DNS or OpenDNS. Forwarding DNS servers can help offload the DNS resolution process from local resolvers and benefit from the caching and performance improvements of the forwarder.

It's important to note that DNS queries typically follow a recursive resolution process, where the resolver iteratively contacts the appropriate DNS servers until it obtains the final IP address. This process starts from the root DNS servers, goes through TLD servers, and finally reaches the authoritative DNS servers for the specific domain.

The DNS system plays a critical role in the functioning of the internet, enabling the seamless translation of domain names into IP addresses. By distributing the responsibility across different types of DNS servers, the system ensures efficient and reliable domain name resolution for billions of internet users worldwide.

<u>2. TCP/IP:</u>
TCP/IP (Transmission Control Protocol/Internet Protocol) is a suite of protocols that enables communication over the internet. TCP provides reliable and ordered delivery of data packets between devices. It breaks down the data into smaller packets, numbers them, and reassembles them in the correct order on the receiving end. IP is responsible for addressing and routing these packets across networks, ensuring they reach their intended destination.

TCP/IP (Transmission Control Protocol/Internet Protocol) is a protocol suite that provides the foundation for communication on the internet. It can be understood in the context of the OSI (Open Systems Interconnection) model, which is a conceptual framework that standardizes network communication into seven layers. TCP/IP does not directly align with the OSI model's layered structure, but we can map its functionality to the respective layers as follows:

Physical Layer (Layer 1): The Physical Layer of the OSI model deals with the physical transmission of data over the network.

Data Link Layer (Layer 2): The Data Link Layer provides error-free transmission over the physical layer.

Network Layer (Layer 3): The Network Layer is responsible for logical addressing and routing of data packets across different networks. In TCP/IP, the IP (Internet Protocol) resides at this layer. IP provides logical addressing and routing capabilities, enabling the identification of hosts and the routing of packets between different networks.

Transport Layer (Layer 4):
The Transport Layer ensures reliable and orderly data delivery between end systems. TCP (Transmission Control Protocol) operates at this layer in the TCP/IP suite. TCP provides reliable, connection-oriented communication by establishing and maintaining a connection, breaking data into packets, sequencing them, and reassembling them at the destination. TCP also handles flow control, congestion control, and error recovery.

Session Layer (Layer 5): The Session Layer manages the establishment, maintenance, and termination of sessions between applications.

Presentation Layer (Layer 6): The Presentation Layer deals with data representation and transformation, including encryption, compression, and data formatting.

Application Layer (Layer 7): The Application Layer represents the interface between the network and the user. It encompasses the protocols and services that directly interact with applications. Examples of protocols operating at the TCP/IP Application Layer include HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), and DNS (Domain Name System).

It's important to note that while TCP/IP and the OSI model provide different perspectives on network communication, they serve as useful frameworks to understand and organize the protocols and functionalities involved in transmitting data over networks. TCP/IP is a widely adopted protocol suite that has been instrumental in the growth and development of the internet.

<u>3. Firewall:</u>
A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predefined security rules. It acts as a barrier between internal networks and external networks (such as the internet) and inspects network traffic to determine if it should be allowed or blocked. Firewalls can prevent unauthorized access, filter malicious traffic, and protect against various types of cyber threats.

A network firewall is a crucial component of network security that acts as a barrier between an internal network and external networks, such as the internet. It monitors and controls incoming and outgoing network traffic based on predefined security rules. Here are some key aspects to consider when discussing network firewalls in detail:

Firewalls can be categorized into several types, including:

Packet Filtering Firewalls: These firewalls examine packets of data based on predefined rules, such as source and destination IP addresses, ports, and protocols. They allow or block packets based on these criteria.

Stateful Inspection Firewalls: Stateful firewalls not only analyze individual packets but also maintain information about the state of network connections.

Application-Level Gateways (Proxy Firewalls): These firewalls act as intermediaries between internal clients and external servers. They inspect application-layer protocols, such as HTTP, SMTP, or FTP, and make security decisions based on the application data.

Next-Generation Firewalls: Next-Generation Firewalls (NGFWs) combine traditional firewall functionalities with additional advanced features. They can perform deep packet inspection, intrusion prevention, application awareness, and integrate with other security technologies like antivirus and intrusion detection systems

Implementing a network firewall is a fundamental security measure that helps protect organizations from unauthorized access, external threats, and data breaches. By defining and enforcing security policies, filtering network traffic, and providing additional security features, firewalls play a vital role in maintaining the integrity and confidentiality of network communications.

<u>4. HTTPS/SSL:</u>
HTTPS (Hypertext Transfer Protocol Secure) is the secure version of HTTP, the protocol used for transmitting data over the internet. HTTPS encrypts the data exchanged between a client (e.g., your browser) and a web server to ensure its confidentiality and integrity. SSL (Secure Sockets Layer) and its successor, TLS (Transport Layer Security), are protocols used to establish secure connections. They employ cryptographic techniques to encrypt the data and provide authentication, ensuring that the data is protected from eavesdropping and tampering.

HTTP (Hypertext Transfer Protocol) and SSL (Secure Sockets Layer), now commonly referred to as its successor TLS (Transport Layer Security), are protocols used to enable secure communication over the internet. Let's discuss HTTP and SSL/TLS in detail:

Hypertext Transfer Protocol (HTTP):
HTTP is a protocol that governs the communication between web browsers and web servers. It allows clients (web browsers) to request web resources, such as HTML pages, images, and videos, from servers and receive responses containing the requested content. HTTP is based on a client-server model, where the client initiates a request, and the server responds with the requested information.

Secure Sockets Layer (SSL) and Transport Layer Security (TLS):
SSL and its successor TLS are cryptographic protocols designed to provide secure communication over the internet. They establish an encrypted connection between a client and a server, ensuring the confidentiality, integrity, and authenticity of the data exchanged.

HTTPS: HTTPS (HTTP Secure) is the secure version of HTTP that utilizes SSL/TLS. It operates on a different port (443) and provides secure communication between the client and server. HTTPS ensures that data transmitted between the browser and the server is encrypted and protected.

Handshake Protocol: SSL/TLS uses a handshake protocol to establish a secure connection. During the handshake, the client and server negotiate encryption algorithms, exchange cryptographic keys, and verify each other's digital certificates.

The use of SSL/TLS in combination with HTTP, resulting in HTTPS, is essential for secure communication on the web. It ensures that sensitive data, such as login credentials, credit card information, and personal details, are protected from interception and unauthorized access. Websites that employ HTTPS provide users with increased security and privacy, fostering trust and confidence in online transactions and interactions.

<u>5. Load Balancer:</u>
A load-balancer is a device or software component that evenly distributes incoming network traffic across multiple servers or resources to optimize performance and ensure high availability. It helps prevent overloading of individual servers by spreading the workload across a pool of servers. Load-balancers use various algorithms to determine how traffic is distributed, such as round-robin, least connections, or weighted distribution.

Load balancers are an essential component of modern web architectures, helping distribute network traffic across multiple servers to improve performance, availability, and scalability. Load balancers act as intermediaries between clients and servers, distributing incoming traffic based on a set of predefined rules. Let's discuss load balancers in detail:

Load balancing algorithms can be designed to distribute traffic based on various criteria, such as:

Round-robin: Distributes requests evenly among servers, with each server receiving an equal number of requests.
Least connections: Directs traffic to the server with the fewest active connections.

IP Hash: Assigns requests based on the client IP address.
Session Persistence: Ensures that requests from the same client are directed to the same server, ensuring session continuity.

Load balancers also monitor server health and availability, automatically routing traffic to healthy servers and avoiding those that are experiencing issues.

Types of Load Balancers:
There are several types of load balancers, each with different deployment models, architectures, and features. Some of the most common types include:

Hardware Load Balancers: These are physical appliances that are installed in the data center and are designed to handle high volumes of traffic. Hardware load balancers offer high performance, reliability, and advanced features such as SSL acceleration, caching, and firewall protection.

Software Load Balancers: These are software-based solutions that are deployed on virtual machines or containers. Software load balancers offer flexibility, scalability, and cost-effectiveness, making them a popular choice for modern cloud-based applications.

Application Delivery Controllers (ADCs): These are advanced load balancers that offer additional functionality, such as SSL offloading, content caching, and application-level security features.

Global Server Load Balancers (GSLBs): These are load balancers that operate across multiple data centers or geographic locations, providing high availability and disaster recovery capabilities.

In summary, load balancers are an essential component of modern web architectures, offering improved performance, scalability, and reliability. They provide traffic distribution, health monitoring, and advanced features that enhance web application security and simplify management.

<u>6. Web Server:</u>
A web server is software that runs on a server and handles HTTP requests from clients (browsers). It delivers web content, such as HTML, CSS, JavaScript files, images, and videos, in response to client requests. Web servers host websites and process the requests by retrieving and serving the requested files. Popular web server software includes Apache HTTP Server, Nginx, and Microsoft IIS.

Web servers are software applications that handle client requests and serve web content over the internet. They play a vital role in hosting websites and delivering web pages to users' browsers. Two popular web server software examples are Nginx and Apache HTTP Server, with combined control of over 50% of the global web server market.

Both Nginx and Apache are highly capable web servers, each with its own strengths and characteristics. Nginx excels in handling concurrent connections, load balancing, and serving static content efficiently. Apache, on the other hand, is renowned for its modularity, flexibility, and extensive ecosystem of modules.

The choice between Nginx and Apache often depends on specific use cases, performance requirements, existing infrastructure, and personal preferences. Many organizations employ a combination of both servers, utilizing Nginx as a reverse proxy or load balancer in front of Apache.

In conclusion, web servers such as Nginx and Apache are fundamental components in hosting websites and serving web content. While Nginx is known for its high-performance and concurrency handling capabilities, Apache offers modularity, flexibility, and a vast ecosystem of modules. Understanding the features and characteristics of these web servers can help in choosing the appropriate solution based on specific needs and requirements.

<u>7. Application Server:</u>
An application server is software that provides an environment for executing and managing applications. It is commonly used in the context of web applications. Application servers handle the business logic and processing required by web applications, which may involve executing code written in various programming languages. They provide services such as database access, security, session management, and scalability for the applications running on them.

Application servers play a crucial role in modern web application architectures by providing a runtime environment and necessary services to deploy and run applications. They act as an intermediary between the web server and the backend components of an application, handling business logic, data processing, and integration with other systems. Let's delve into application servers in detail:

Functionality:
Application servers offer various services and capabilities to support the execution of web applications. Some key functionalities include:

Middleware Services: Application servers provide middleware services such as database connectivity, transaction management, messaging, and caching. They facilitate communication between the application and other systems or components.

Business Logic Execution: Application servers execute the business logic of web applications. They process user requests, perform computations, access databases, and generate responses based on application-specific rules and workflows.

Session Management: Application servers manage user sessions and maintain state information for each user. This enables the server to track user interactions, handle session timeouts, and provide personalized experiences.

Security: Application servers offer security features, such as user authentication, authorization, and data encryption. They help protect sensitive information and ensure secure communication between the application and users.

Scalability and Load Balancing: Application servers often support clustering and load balancing to handle increased traffic and provide high availability. They distribute incoming requests across multiple server instances to ensure optimal resource utilization and performance.

In conclusion, application servers play a vital role in modern web application development and deployment. They provide a runtime environment and essential services that enable the execution of business logic, integration with other systems, and efficient resource utilization. With support for various programming languages and frameworks, application servers simplify development, enhance scalability, and offer security and management features. Choosing the right application server based on the specific requirements of the application is crucial for achieving optimal performance, scalability, and maintainability.

<u>8. Database:</u>
A database is a structured collection of data organized and managed to allow efficient retrieval, storage, and manipulation of information. It stores data in a structured format, making it easier to search, query, and update. Databases are used to store various types of data for web applications, such as user information, content, product catalogs, and more. Popular database management systems include MySQL, Oracle, Microsoft SQL Server, and PostgreSQL.

Databases are fundamental components of modern software systems, serving as repositories for structured data storage, retrieval, and management. They provide a structured and efficient way to store, organize, and access data, enabling applications to perform tasks such as data analysis, reporting, and transaction processing. Let's explore databases in detail:

Types of Databases:
There are various types of databases available, each designed to address specific data storage and retrieval needs. Some common types include:

Relational Databases: Relational databases, such as MySQL, PostgreSQL, and Oracle Database, organize data into tables with predefined relationships. They use SQL (Structured Query Language) for data manipulation and support ACID (Atomicity, Consistency, Isolation, Durability) properties to ensure data integrity and transactional consistency.

NoSQL Databases: NoSQL (Not Only SQL) databases, including MongoDB, Cassandra, and Redis, are designed for handling unstructured or semi-structured data. They offer flexible schemas and scalable data models, making them suitable for handling large volumes of data and accommodating changing requirements.

Object-Oriented Databases: Object-oriented databases, like db4o and ObjectDB, store data in the form of objects, allowing direct storage and retrieval of complex data structures. They are often used in object-oriented programming environments.

Graph Databases: Graph databases, such as Neo4j and Amazon Neptune, are optimized for storing and querying graph-like data structures. They excel in modeling complex relationships and performing graph-based queries efficiently.

Time-Series Databases: Time-series databases, like InfluxDB and Prometheus, specialize in storing and analyzing time-stamped data, such as sensor readings, logs, and financial data. They provide optimized storage and querying mechanisms for time-based data analysis.

In conclusion, databases are essential components for managing and organizing structured data. Choosing the right database type, considering the data model, and implementing effective database management practices are crucial for ensuring data integrity, performance, security, and scalability. Understanding these aspects enables developers and administrators to design and maintain databases that meet the specific requirements of their applications and provide efficient and reliable data storage and retrieval capabilities.


These network components work together to enable the smooth functioning and secure delivery of data over the internet, ensuring efficient communication between clients and servers and facilitating the retrieval and storage of information.