The interview process is very length mainly due to high queue of applicants. The interview process focuses on linux, networking and software engineering principles. Best way to prepare is to read-up on system-admin books and networking books. For coding challenges there are many resources available.

Two rounds of interviews. A recruiter will guide you through the process. Covered a lot of questions, both technical and HR / People interaction related. The interviewers are friendly and helpful during the interview.