When a user opens a browser and enters a URL:
The client checks whether there is an IP address cached for that URL. If not, it sends a request to the nearest DNS server for domain name resolution, querying up to the root DNS server if necessary. Once the query succeeds, the result is returned to the client.
The browser sends the request to the web server at the IP address corresponding to the URL.
This server may be a single standalone server, a lightweight load balancer, or a cluster.
If it is a load balancer or cluster, the servers internally synchronize based on timestamps to ensure the data is up to date; if not, synchronization is performed.
If the request involves application-level calls, the request is forwarded to the application server, which returns the result to the web server.
The web server executes programs written in the relevant dynamic languages, communicates with database servers and related files, and finally sends the resulting web page data back to the browser.
Based on transport protocols such as HTTP and HTTPS, the web server’s data is transmitted back to the browser, which then parses and renders the web page.
Finally, the user sees the web page.
