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

When you type a URL in the browser and press 'enter', the following takes goes on behind the scenes:

1. DNS Requests:
The browser first checks its cache for the IP address corresponding to the entered URL. In the event that the IP address is not in cache memory, the browser sends a DNS request to the DNS server specified in the network settings. The DNS server responds with the IP address of the server hosting the website.

2. TCP/IP:
Once the IP address is obtained, the browser establishes a TCP/IP connection with the server. This connection is established using a three-way handshake process which works as follows: Firstly, the client sends a SYN packet to the server. Secondly, the server responds with a SYN-ACK packet. Lastly, the client responds with an ACK packet.

3. Firewall:
Before the connection is established, the firewall on the client or server side might block the connection if the firewall policies do not permit traffic on the specified port.

4. HTTPS/SSL:
If the website uses HTTPS, the browser initiates a TLS/SSL handshake with the server to establish a secure encrypted connection. The browser verifies the server’s digital certificate to ensure that it is trusted, and then they negotiate the encryption protocol and keys to be used for the secure communication.

5. Load-balancer:
In cases where the website is hosted on multiple servers, a load-balancer may distribute the incoming traffic to the servers based on the load-balancing algorithm. The load-balancer ensures that the servers receive only the amount of traffic they can handle.

6. Web server:
Once the connection is established, the browser sends an HTTP request to the web server requesting the web page. The web server processes the request, retrieves the requested page from the file system or database, and sends an HTTP response containing the requested page back to the browser.

7. Application server:
If the website is dynamic, the web server may forward the request to an application server that executes the necessary business logic and generates the dynamic content. The application server retrieves the necessary data from the database and generates an HTTP response that is sent back to the web server.

8. Database:
If the website is database-driven, the application server retrieves data from the database and generates dynamic content. The database server will then retrieve the requested data from the database which it sends back to the application server.

Finally, upon completion of this data request and retrieval process, the HTTP response containing the requested web page is received by the browser, which then renders it on the screen for the user to view.