Step 1: DNS Resolution (Finding the IP Address)

• What happens:
  The browser needs to know the IP address of www.amazon.in. It first checks its local cache, then the operating system cache, and if not found, it queries a DNS server. The DNS server replies with the IP address (e.g., 52.95.120.xxx).

• Protocol Used:

  • DNS (Domain Name System), which usually runs over UDP port 53, though TCP is also used for larger responses.

• Why:
  Computers communicate using IP addresses, not domain names. DNS converts the human-readable domain into a machine-readable IP address.

Step 2: Establishing a TCP Connection

• What happens:
  Once the IP address is known, the browser establishes a connection to the Amazon server using the TCP three-way handshake (SYN → SYN-ACK → ACK).

• Protocol Used:

  • TCP (Transmission Control Protocol) over port 443 (because HTTPS is being used).

• Why:
  TCP provides a reliable, connection-oriented channel for data transfer, ensuring that packets are delivered in order and without errors.

Step 3: TLS/SSL Handshake (Securing the Connection)

• What happens:
  Since the URL starts with https://, the browser and server negotiate encryption settings to establish a secure channel. This includes exchanging certificates, agreeing on encryption algorithms, and generating session keys.

• Protocol Used:

  • TLS (Transport Layer Security) (modern replacement of SSL).

• Why:
  This ensures confidentiality (data is encrypted), integrity (data is not tampered with), and authenticity (the website is verified as genuinely Amazon and not a fake).

Step 4: Sending the HTTP Request

• What happens:
  After the secure channel is ready, the browser sends an HTTP request for the page. For example, it sends a GET / HTTP/1.1 or GET / HTTP/2 request to Amazon’s server, asking for the homepage. The request also includes headers like browser type, supported languages, cookies, and session details.

• Protocol Used:

  • HTTP/2 or HTTP/3 (over TLS and TCP/UDP).

• Why:
  HTTP defines how browsers and servers exchange information like web pages, images, or videos. HTTPS ensures that this exchange is secure.

Step 5: Server Processing and Sending the HTTP Response

• What happens:
  The Amazon web server processes the request, interacts with databases, applies business logic (like showing personalized offers), and prepares a response. The response includes an HTTP status code (200 OK if successful) and the HTML content of the page. This data is sent back to the browser over the same secure TCP/TLS connection.

• Protocol Used:

  • HTTP/2 or HTTP/3 (still over TLS).

• Why:
  This is the actual delivery of web content from the server to the client in a structured format.

Step 6: Browser Rendering the Webpage

• What happens:
  The browser receives the HTML, parses it, and then makes additional requests for images, CSS files, JavaScript, and other resources. Each of these may go through the same DNS, TCP, and TLS steps (though often cached or kept alive via persistent connections). Finally, the browser renders the complete Amazon homepage on your screen.

• Protocol Used:

  • HTTP/2 or HTTP/3 for fetching resources.

  • Underlying transport continues to be TCP/TLS.

• Why:
  Rendering converts raw HTML/CSS/JS into a user-friendly interface with text, product images, navigation menus, and interactive features.