This question already has an answer here:
I applied for a software development job at a unicorn. The job ad did not mention having tons of experience as a requirement.
I went to the first interview with a manager, and he asked me how would I design a particular system. Then he proceeded to ask me how I would scale the system. I got the impression that he liked my answers and left the interview having a good feeling.
A week later HR calls me and says that they were not going to continue with my application. I was taken aback. They said that I lacked technical skills. She asked me whether I left the interview having any concerns and I said "no". She explained to me why they rejected me but to be honest I didn't understand what she said.
I don't understand why companies expect applicants to be able to design a system from the ground up. IMO, system design is an area in which you need to have experience in order to do it well and understand the tradeoffs of a design. I think I understand the basic concepts behind system design but this seems to be not enough. I kind of get the feeling that the reason I flunk all my applications is because I lack experience in this particular area, but it's like a chicken and egg problem. How do I get experience if I don't have experience?
Also, since I did not understand the reason they rejected me over the phone, should I ask them to send me the reasons over email so I can learn from my mistakes? Or would this likely burn a bridge?