What happens when you enter URL – Step by Step

Learn step by step what happens when you enter URL in the browser or when you click on a link.

When you click on a URL or type a domain name into your web browser’s address bar, several steps occur to facilitate the connection to the corresponding website / URL:

  1. Domain Name Resolution: The browser initiates a Domain Name System (DNS) lookup to translate the human-readable domain name (e.g., www.cisnol.com) into an IP address. The browser checks its cache first to see if it already has the IP address for the domain. If not, it sends a DNS query to a DNS server, typically provided by your Internet Service Provider (ISP).
  2. DNS Server Lookup: The DNS server receives the query and checks its own cache to see if it has the IP address for the domain. If not, it performs a recursive search starting from the root DNS servers, which then directs the query to the appropriate top-level domain (TLD) server (e.g., .com, .org, .net).
  3. TLD Server Lookup: The TLD server responds with the authoritative name server for the requested domain (e.g., ns1.example.com).
  4. Authoritative Name Server Lookup: The DNS server queries the authoritative name server for the IP address associated with the domain name.
  5. IP Address Retrieval: The authoritative name server responds with the IP address associated with the domain name.
  6. Establishing a TCP Connection: The browser initiates a Transmission Control Protocol (TCP) connection to the web server at the retrieved IP address on port 80 (HTTP) or port 443 (HTTPS).
  7. HTTP/HTTPS Handshake: If the website uses HTTPS, a secure handshake occurs between the browser and the web server to establish an encrypted connection.
  8. HTTP Request: The browser sends an HTTP request to the web server, specifying the requested resource (e.g., the specific webpage).
  9. Server Processing: The web server receives the HTTP request, processes it, and retrieves the requested resource.
  10. HTTP Response: The web server sends an HTTP response back to the browser, containing the requested resource (e.g., HTML content, images, scripts).
  11. Rendering: The browser receives the HTTP response and renders the webpage, displaying it to the user.

Throughout this process, multiple layers of protocols, including DNS, TCP, and HTTP/HTTPS, are involved in ensuring the successful retrieval and rendering of the requested webpage.