What occurs in the background when you access a Bitly URL in your web browser?

This question seeks to gauge your understanding of URL shorteners, particularly Bitly, and their functionality. The interviewer is looking for insights into HTTP redirection, DNS resolution, how servers process requests, and possibly even database queries if you elaborate on how Bitly stores and retrieves the mappings for shortened URLs. An ideal response should detail the sequence of events that occurs when you enter a shortened Bitly URL into your browser, leading to the display of the intended webpage. This sequence includes the following steps: Inputting the Bitly link into the URL bar. The browser initiates a DNS resolution request to determine the destination for the HTTP request. The Bitly server receives the HTTP request and performs a database lookup for the corresponding long URL associated with the Bitly link. A HTTP 301 redirect response is sent from Bitly back to your browser. The browser then repeats the process for the long URL.

When you access a Bitly URL in your browser, several processes take place in the background. It begins with you entering the Bitly link into the address bar of your browser and hitting enter. Your browser then makes a DNS resolution request to your Internet Service Provider (ISP) to locate the IP address of the Bitly server. After the IP address is obtained, the browser issues an HTTP GET request to the Bitly server. The server checks its database, which links the shortened Bitly URLs to their corresponding longer URLs. If your Bitly URL exists in the database, the server responds with an HTTP status code of 301 Moved Permanently. This HTTP 301 response includes the original long URL in the 'location' header field. Your browser processes this information, retrieves the location from the response header, and sends a new HTTP GET request to the long URL. Once the server for that URL responds with a HTTP 200 OK status and provides the HTML content of the page in the message body, your browser is able to render and display the webpage.

When you visit a Bitly URL, it initiates a sequence of system events. To start, you enter the short URL into your browser. The DNS resolver then translates the domain name 'bitly.com' into an IP address. The browser sends an HTTP GET request to that IP address. The server at this IP retrieves the path from the GET request and searches for the 'key' in its database, which stores a key-value pair of shortened URLs along with their corresponding full URLs. After locating the matching full URL, the server replies with an HTTP 301 status code, indicating that the requested resource has been permanently moved, and includes the full URL in the 'Location' header. Your browser gets this response and automatically sends a new HTTP GET request to the URL specified in the 'Location' header. This cycle continues until it reaches a server that returns an HTTP 200 status along with the page content, which the browser then renders.