First round was fine, standard phone screening going over aspects of my resume. Second round was very unexpected. After first round I was told to expect a technical dive into my resume/past experiences, but instead was just hammered with OS/Networking questions. Granted, I should have known these topics; I had never studied them before, and nowhere in my resume did I indicate I would have known anything about these topics. I do appreciate them extending an interview, but overall, it was a colossal waste of time.

TCP vs UDP and when to use one over the other.