AT&T Systems Engineer interview questions

I initially had a phone screen with one a team manager. Questions were basic Solaris questions, some network questions and a detailed overview of the job and location. I was contacted to come in for a group interview with more team managers. I was given a more detailed overview of the culture, the company goals and then was peppered by technical questions. I was asked how to calculate IP subnets which I struggled to answer. I was assured that they use a calculator and not to worry that I couldn't do this on the fly. Other than that the questions were fairly easy. I felt I had a great interview and was certain I was going to get an offer. Didn't happen, they chose someone else, making me wonder about that IP question. I was sad! I really wanted this job but who knows maybe it will open again and they will hire me.