Infosys interview question

In the first round there were some general questions regarding web development react, node, non relational databases etc. and one problem with sorting was asked I don't remember what it was exactly. In the second round I was asked to make a web application with sign up and login functionality. After this I was asked about different technologies of MERN stack as the requirement was for MERN stack developer. I was not able to build the application in time though.