What happens when you type 'www.google.com' in your browser and press Enter

 

Introduction

Several processes run in the background mode before your computer displays the Google homepage when you type "https://www.google.com" into your web browser and press the enter key.

Thankfully, all of these events take place in a fraction of a second and are invisible to you. Have you ever pondered what actually occurs in the background?

1.    Your browser sends a request to the DNS (domain name system) server, which serves as an address book for all domain names. This then sends back the exact IP address of the server, which https://www.google.com points to.

2.    The browser checks for the presence of "https://" at the beginning of the URL. This indicates that a secure, encrypted connection is required between the browser and the website. The browser then initiates a secure handshake with the web server to establish this encrypted connection.

3.    Once the secure connection is established, the browser sends an HTTP request to the server, asking for the Google homepage. This request contains a lot of information, including the type of browser being used, the language preferences of the user, and the version of the HTTP protocol being used.

4.    The server at Google receives the request and processes it. It checks the requested URL and looks for the corresponding web page or file. In this case, it finds the Google homepage and begins to assemble the content to send back to the browser.

5.    The server sends back an HTTP response to the browser. This response contains the HTML, CSS, and JavaScript files needed to display the Google homepage. The response also includes information about the status of the request (e.g., whether it was successful or not) and any additional metadata, such as cookies or caching directives.

6.    The browser receives the response and begins to render the Google homepage. It first reads the HTML file and creates a Document Object Model (DOM) that represents the structure of the page. It then parses the CSS file and applies the appropriate styles to each element on the page. Finally, it executes the JavaScript code and makes any necessary changes to the page (e.g., loading dynamic content).

7.    The browser displays the fully rendered Google homepage to the user. The user can now interact with the page, perform searches, and click on links to navigate to other pages on the internet.

 

LET'S EXAMINE WHAT OCCURS IN MORE DETAIL STEP BY STEP:

1.      DNS

When you access a website or domain name using your browser, the browser stores information about that domain name (its DNS record).

As a result, whenever you type a domain name into your web browser, such as "google.com," the browser first checks its cache to determine if it has a recent copy of the DNS record for that domain.

It will utilize the IP address stored in the cache to submit a request to the server if a recent copy of the DNS records for that domain is available. 

Because a call to the DNS server is not necessary, the process of resolving the domain name to an IP address proceeds more quickly.

The browser will submit a request to the DNS server to resolve the domain name to an IP address if the cache of the browser does not contain a current copy of the DNS record or if the DNS record has changed since it was last cached.

Let's look at the various steps in the DNS lookup process. The DNS lookup process is described in greater detail below:

  a.   Immediately after typing google.com into your browser. 

First, the browser and the operating system checked their caches to determine if they had the IP address for google.com.  Nevertheless, because they didn't, the OS is now contacting the resolver.

b.     Resolver

The resolver server is usually your ISP (Internet Service Provider). All resolvers must know one thing: where to locate the root server.

To see if it has a current copy of the DNS record for that domain, the resolver looks in its cache. If so, the IP address is returned to the browser.

A request is made to a root server if the resolver does not already have a      recent copy of the DNS record.

c.    Root Server

The resolver then asks the root server: I am trying to find the IP address for the website google.com. The root server sent the reply. Sorry, resolver, I don't know where to find google.com. But I can tell you where to find the.COM TLD server.

d.   .COM TLD server

I am afraid I don't know the IP address for google.com, but I have found the authoritative name servers! The.COM domain found the authoritative name servers for the domain google.com.

e.   Authoritative Name Severs

The authoritative name server responds with the IP address for google.com. Google's IP address is 8.8.8.8. The resolver then sends the IP address to the browser.

The resolver finally got the answer he was looking for! Hurray for the authoritative name server!

It was so cool visiting everyone!

The root told me where to find the.COM server.

The TLD server gave me the authoritative name server addresses.

Then, ns1.google.com gave me the IP for google.com.

 

2.      TCP/IP

TCP/IP stands for Transmission Control Protocol/Internet Protocol. TCP/IP is a set of standardized rules that allow computers to communicate on a network such as the internet.

TCP works with the Internet Protocol (IP), which defines how computers send packets of data to each other. Together, TCP and IP are the basic rules that define the internet.

They work together to establish a connection between a client and a server and facilitate the transmission of data between them.

When you enter "google.com" into a web browser, the browser uses TCP/IP to establish a connection with the server that hosts the website.

Here's what happens in more detail:

The browser sends a request to the server using IP to establish a connection.

The server receives the request and sends back an acknowledgment acknowledging the request to establish a connection. This is the three-way handshake protocol.

Once the three-way handshake protocol is complete, the browser can send a request for the webpage it wants to access (in this case, the homepage of google.com). This request is sent using TCP, which ensures that the request is transmitted reliably and in the correct order.

The server receives the request and sends back the HTML code for the homepage of Google.com to the browser. This response is also sent using TCP to ensure reliable transmission.

The browser receives the HTML code and uses it to render the webpage on your screen. Any resources (such as images) that the webpage needs are also requested and received using TCP/IP.

 

3.      FIREWALL

A firewall is a security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. Its primary purpose is to protect a network from external threats, such as hackers and malware.

When you type "google.com" into your browser's URL, the request that your browser makes to Google's server passes through the firewall on its way there. The firewall checks the incoming request to make sure it is allowed based on its security rules.

There are two main types of security rules that a firewall uses to check incoming requests:

Rules that allow or block traffic based on the source and destination of the request for example, a firewall may be configured to block all traffic from certain countries or to allow only certain IP addresses to access the network.

Rules that allow or block traffic based on the type of traffic for example, a firewall may be configured to block all traffic on certain ports (such as those used by malware) or to allow only certain types of traffic (such as HTTP or HTTPS).

If the incoming request meets the security rules set by the firewall in front of Google's server, it is allowed through, and the browser is able to access the website.

However, if the request does not meet the security rules, it is blocked, and the browser is unable to access the website.

 

4.      HTTPS/SSL

HTTPS (Hypertext Transfer Protocol Secure) is a secure version of the HTTP protocol used to transmit data on the internet. It is used to encrypt the data transmitted between your browser and Google's server.

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are encryption protocols that are used to secure the data transmitted over HTTPS.

When your browser establishes a connection with Google's server using HTTPS, your browser and Google's server first agree on the version of SSL/TLS to use and then create a secure, encrypted channel for transmitting the data.

Let me use an analogy to explain what is going on here.

HTTPS is like a locked box that is used to send messages over the internet. When you want to send a message using HTTPS, you put the message in the locked box and send it to the person you want to receive the message. Only the person you are sending the message to has the key to unlock the box and read the message.

SSL and TLS are like special codes that are used to lock and unlock the box. When you want to send a message using HTTPS, you and the person to whom you are sending the message must agree on the code to use to lock and unlock the box. This way, only you and the person to whom you are sending the message know the code and can read the message.

When you type "google.com" into your browser, the browser is like the person sending the message. The server that hosts google.com is like the person receiving the message. The browser sends a request for the webpage using HTTPS, which is like putting the request in a locked box and sending it to the server. The server then sends the webpage back to the browser using HTTPS, which is like putting the webpage in a locked box and sending it back to the browser.

 

5.      LOAD-BALANCER

A load balancer is a device that acts as a reverse proxy and distributes network or application traffic across a number of servers.

Its primary function is to ensure that the traffic is distributed evenly across the servers in order to avoid overloading any single server and to increase the overall capacity and reliability of the system.

A company like Google, which receives billions of website visitors a day, will need a lot of servers to serve all these users. Therefore, there will be a need for them to set up a load balancer to ensure that some of the servers are not overburdened while others are being underutilized.

In the case of a browser trying to access google.com, the load balancer would receive the incoming request from the browser and then forward it to one of the servers in the Google server network. The particular server chosen will depend on the type of load-balancing algorithm implemented.

 

6.      WEB SERVER

A web server is a computer program that is responsible for handling requests for web pages from clients (such as a browser trying to access google.com). When a client sends a request for a web page to a web server, the server processes the request and returns the appropriate response to the client.

This means that when trying to access google.com, Google's server will receive a request from the load balancer.

The web server would then process the request and generate a response, which would typically include the HTML, CSS, and JavaScript files that make up the web page.

The web server would then send this response back to the load balancer, which would forward it on to the browser. The browser would then use the HTML, CSS, and JavaScript files to render the web page for the user.

 

 7.     APPLICATION SERVER

Unlike the web server, the application server handles dynamic content. When using "google.com", the application server will be responsible for generating the search results (which change based on the query you put into the search engine).

When you submit a search query to Google, the request is first sent to the load balancer, which forwards it to one of the web servers in the Google server network. The web server then sends the request to the application server, which processes the request and generates the search results.

Depending on the complexity of the search query, the application server may need to make a request to a database in order to retrieve the necessary data.

For example, if you are searching for a specific product on an e-commerce website, the application server may need to retrieve information about the product from a database.

Once the application server has obtained the necessary data, it sends it back to the web server, which includes it in the response that is sent back to the browser. The browser then uses this information to display the search results to you.

 

 

8.      DATABASE

A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database is usually controlled by a database management system (DBMS). There are two types of databases: relational and non-relational, which both use DBMS to create, edit, delete, and maintain data. In this case, the content of what you search for will be stored in a database.

 

CONCLUSION

The Google server receives an HTTP request from your browser when you input https://www.google.com and click Enter, and it responds by providing the necessary files to display the Google homepage. You can use the browser to engage with Google's search engine and other services after it processes these files and presents the page to you. Thanks to the robust network infrastructure that supports the internet, the entire process is completed in a couple of seconds.