First, I was contacted by Jon Oberheide, the company's co-founder and CTO. He asked me about how I heard about Duo, my security background (explaining what I listed in the Resume), my career goal, etc. Then, I was flown to Ann Arbor for an onsite interview. I met the team there. Everyone was very nice and knowledgeable. They talked to me about the lab team, the projects that they are working on, and the direction that they'd like to take for future projects. I was asked a couple of programming questions, and some general exploitation questions (since my background is in exploitation). The programming questions are not complicated, but they do target your knowledge about algorithms and data structures. The exploitation questions are not hard if you play wargames and CTF, homework knowledge from your computer security class might not be enough. Code is written by hand, no "real-time" exploit development is required. A few days later, I was sent a take-home assignment where I picked one question out of 3, write code for it and send back. Question is not complicated, but very fun.