Applied online and also met a recruiter at a career fair in mid-February that didn't seem too enthusiastic about my resume. After about three days, I got an email asking when I was free for a phone screening. Responding to the email lead to a bounce-back "Thanks for applying to Zayo" email, but eventually someone from HR replied and set up the phone screen for about five days later.
At the screening she asked what I knew about Zayo (which was a decent amount because I was interested in telecomm for some time) and how I would go about making a dynamic chart in MS PowerPoint. The entire thing took about 30min.
After the screening, I got an email about interview scheduling (although they never told me the interview was on-site until about an hour before my interview) for two weeks later.
I interviewed with three hiring managers back-to-back in mid-March, which took about two hours total, then was told I'd have a response in a week. The three managers all asked me: what I knew about Zayo's operations, pretty basic, general business/Operations Management questions and what classes I'd taken, had yet to take, and what the overall curriculum for my major looked like. It was very conversational. They also asked about my proficiency in Excel, Visio, and PowerPoint.
After all of the interviews, an HR rep asked me what team appealed most to me and why.
After a week, I called to see what the status of their decision process was, and was told they'd need another week to decide due to the VP of the team being out of town, and all hiring being at his final discretion. By the end of another week, they called and offered me a position for the summer (which, by the end of the second week of the internship, became an ongoing position, through the school year). The entire application/interview process took about six weeks in total, though it seemed to go a lot faster than that. Great experience, the only time hurdles seemed to be HR working with so many applicants concurrently and needing to reschedule often, which is understandable.