There were two interview tiers. The first one was a phone screen. I was asked questions about the basics of the internet and cyber security. The second tier was onsite. There were 5 interviews. The first was with the person who ultimately became my manager. We discussed the projects his team works on and assessed my understanding of them. The second interview asked a few general CS knowledge questions and had a coding exercise. The third was more focused on my knowledge of C++ semantics and libraries. I understood basic C++ semantics pretty well at the time, but my knowledge of the libraries and advanced syntaxes and features was lacking. The forth interview focused on the details of internet communication and secure communication technologies. I had a good understanding of how these things work, but I was a bit fuzzy on some of the details for some of the security processes. The fifth interview was a white boarding session to design an algorithm to solve a twist on a classic CS problem. I didn't know the answer immediately, but that's ok because interviewers are generally more interested to see how you get to the solution and they don't really learn anything about you if you already know it.