
The best way to ace an system design interview is to do Mock Interviews someone.Having solid knowledge base is essential but its totally a different ball game once it comes to application of the knowledge in an interview and that too in very limited time.
I have designed lots of backend systems in my role where some systems are handling 2 billions requests per day. As far as interviews are concerned I have given numerous interviews and have been interviewing candidates on daily basis.
In this call I can help you with structuring the thought process and help you with some tips. This interview will be conducted in similar manner as you would find in real world.