How Does a Browser Communicate With Web Server?
When you enter a web address in your browser’s address bar and hit enter, a complex process begins, involving multiple layers of communication between your browser and the web server hosting the website. Let’s dive deeper into how this communication takes place:
1. DNS Lookup
Before establishing a connection with the web server, your browser needs to resolve the domain name (e.g., www.example.com) to an IP address.
It does this by performing a DNS lookup. The browser sends a request to the Domain Name System (DNS) server, which returns the IP address associated with the domain.
2. Establishing a TCP Connection
Once the IP address is obtained, your browser uses the HTTP or HTTPS protocol to establish a Transmission Control Protocol (TCP) connection with the web server. This connection allows for reliable data transfer between your browser and the server.
3. Sending an HTTP Request
Your browser then sends an HTTP request to the web server using the established TCP connection.
The request includes various details such as the desired resource (e., webpage), request method (GET, POST, etc. ), headers, and cookies.
The HTTP request typically consists of:
- Request Method: Specifies what action is being requested (GET, POST, PUT, DELETE, etc.)
- Headers: Provide additional information about the request (e., user-agent, content-type)
- Cookies: If available, cookies associated with the website are sent along with the request
4. Processing and Responding to the Request
Upon receiving the HTTP request, the web server processes it and generates an appropriate response. The server may execute server-side code, retrieve data from a database, or perform other necessary actions to generate the response.
The HTTP response typically includes:
- Status Code: Indicates the outcome of the request (e., 200 OK, 404 Not Found)
- Headers: Provide additional information about the response (e., content-type, cache-control)
- Response Body: Contains the requested resource (e., HTML markup, images, CSS files)
5. Receiving and Rendering the Response
Your browser receives the HTTP response containing the requested resource and begins rendering it. If the response includes an HTML document, your browser parses the HTML markup and constructs a Document Object Model (DOM) representation of the webpage.
6. Displaying the Webpage
Finally, your browser combines all retrieved resources and renders them as a fully-fledged webpage for you to interact with. The rendered webpage may include text, images, videos, forms, and various interactive elements.
In conclusion, when you enter a web address in your browser’s address bar and hit enter, a series of communication steps occur between your browser and the web server. Understanding this process helps you comprehend how information is transmitted over networks to display websites on your screen.