In preparation for an interview, come ready to discuss your portfolio at length as well as your design process and what design software you are familiar with. Graphic design positions can be very specific to the company so make sure you brush up on the company's current design style and are ready to explain how your style and experience will mesh.
The questions they asked me were too basic, so it wasn't a matter of knowledge they were trying to learn from me. My guess was that they hire on looks instead of skill.
I was able to answer all questions and show portfolio work that matched the questions.