When you type “google.com” into your browser and hit enter, a complex series of events unfolds behind the scenes. While most users focus on the search results, this article delves into the intricate journey of your request, examining What Happens To Alex’s computer during this process. Let’s explore the fascinating sequence of actions triggered by this seemingly simple act.
From Keyboard to Browser: Initiating the Search
The journey begins with the physical act of typing. Each keypress sends an electrical signal to the computer, translated into a scan code and ultimately a character. For Alex, using a USB keyboard, this involves signals traversing the USB controller and being interpreted by the operating system’s HID driver. On a touchscreen device, capacitive sensors detect the touch and trigger a software interrupt, achieving the same outcome.
Once the “Enter” key is pressed, a specific keycode (13) is registered. This triggers further actions depending on Alex’s operating system:
- Windows: A
WM_KEYDOWNmessage is sent to the active application, in this case, the browser. - macOS: A
KeyDownNSEvent is dispatched to the browser application. - Linux: The Xorg server receives the keycode and relays the character to the focused window, the browser’s address bar.
The browser, now aware of the entered text, parses the URL “google.com,” recognizing it as a valid web address.
Resolving the Address: Finding Google’s Servers
Before contacting Google, Alex’s browser needs to find its IP address. This involves a DNS lookup:
-
The browser checks its cache and the local
hostsfile for a pre-existing entry for “google.com.” -
If not found, a request is sent to Alex’s configured DNS server, likely the router or ISP’s DNS. This involves the Address Resolution Protocol (ARP) to determine the MAC address of the gateway.
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The DNS request travels through various network nodes, potentially reaching the root DNS servers, until the authoritative DNS for “google.com” is found. The IP address is then returned to Alex’s browser.
Establishing a Connection: The TCP Handshake
With the IP address, the browser initiates a connection to Google’s server using the Transmission Control Protocol (TCP): A three-way handshake ensures a reliable connection.
- SYN: Alex’s browser sends a synchronization request to Google’s server.
- SYN-ACK: Google’s server acknowledges the request and sends its own synchronization request.
- ACK: Alex’s browser acknowledges the server’s response, completing the connection.
Secure Communication: The TLS Handshake
Since Google uses HTTPS, a Transport Layer Security (TLS) handshake follows, encrypting the communication:
- ClientHello: Alex’s browser sends its supported TLS version and cipher suites.
- ServerHello: Google’s server selects a cipher suite and sends its certificate.
- Key exchange and verification occur, establishing a secure, encrypted connection.
Requesting the Page: The HTTP Request
Finally, Alex’s browser sends an HTTP GET request to Google’s server, asking for the homepage content. The request includes various headers, specifying the browser and accepted content types. Google’s server processes the request and sends back the HTML code for the homepage along with other resources like CSS, JavaScript, and images. Each resource request repeats similar steps involving DNS lookup, connection establishment, and potentially TLS handshake.
Displaying the Page: Rendering and Beyond
Alex’s browser parses the received HTML, constructs the Document Object Model (DOM), and renders the page visually. This involves interpreting CSS styles, executing JavaScript code, and displaying images. The page then appears on Alex’s screen, completing the journey from keypress to Google’s homepage. Further actions, like user interactions with the page, trigger additional processes and network requests.
Conclusion: A Complex Journey for a Simple Action
Typing “google.com” and pressing enter initiates a remarkable chain of events involving hardware, software, networks, and security protocols. While Alex experiences a seamless interaction, understanding what happens behind the scenes reveals the intricate workings of the internet and the complex journey undertaken to display a single webpage.
