The latest articles on DEV Community by DeveloperJoe (@developerjoe). https://dev.to/developerjoe https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F1461575%2Ff465e4e4-ced7-4465-8aef-518268b12dd9.png https://dev.to/developerjoe en DeveloperJoe Wed, 01 May 2024 14:05:50 +0000 https://dev.to/developerjoe/interview-question-explain-the-lifecycle-of-http-request-1pa5 https://dev.to/developerjoe/interview-question-explain-the-lifecycle-of-http-request-1pa5 <p>It is one of the most common question these days for interviews. However I think this question has very little utility. A person can be excellent front end engineer without ever having to know how DNS works. </p> <p>But those who are looking for answers I have written this answer by <a href="https://www.frontendeng.dev/">referring to this excellent resource for frontend engineering</a>. </p> <h2> Request Initiation </h2> <p>Request is often initiated by some user action. Typing url in browser, clicking on a link etc. The browser obtains the link and decides to fetch it for you by first looking at the TLD of the hostname. For example <a href="http://www.mydomain.com/path">www.mydomain.com/path</a> would make the browser first look at mydomain.com </p> <h2> DNS Resolution </h2> <p>Browser queries the DNS service in OS to convert mydomain.com to an ip address. Once it is resolved it looks up the <a href="http://www.mydomain.com">www.mydomain.com</a> which is called the subdomain. </p> <h2> TCP connection </h2> <p>Browser that tries to open a connection on port 80 on the resolved IP address. These days it is going to be port 443 because of SSL. </p> <p>This process involves TCP/TLS handshake. Once the connection is established browser looks at the "path" portion in the URL. </p> <h2> PATH </h2> <p>Browser then presents the rest of the path to the server with which it has oppened the connection. Depending on the request type (GET/POST/DELETE) etc. it might also provide additional data to server. </p> <p>The server will handle this information based on what kind of technology and architecture it has. </p> <h2> The server takes in all the input and generates an outpu </h2> <p>This output is passed back to the server. </p> <p>Both client and server close the TCP connection. </p> <h2> The browser loads everything on the screen. </h2> <p>The browser then looks at the content-Type of the response and renders it in the viewport. </p> <p>There are plenty of steps that go into this rendering process but we will leave that out. </p> <h2> Conclusion </h2> <p>This is what an interviewer is looking for in such questions whether you have good basic understanding of most of these steps or not. </p> <p>[1] <a href="https://www.frontendeng.dev/blog/46-explain-lifecycle-of-internet-request">https://www.frontendeng.dev/blog/46-explain-lifecycle-of-internet-request</a></p> webdev