First you apply online and submit your department and network preferences. Then you will be contacted for a phone interview with an internship recruiter who will ultimately give you three choices of departments you can interview with based on your background and interests (you pick one). Finally you interview with the hiring manager(s) for the department, who will all ask different questions depending on the particular intern position. In my experience your chances are much higher of getting that first phone interview if you're able to meet a recruiter at your school (they got back to me the next day).