Hiring process usually consists of a phone interview, followed by a interview with usually 3 members of management, and then lastly a culture fit interview. The phone interview usually just asks about your relevant history, and tech experienced (DNS, Linux etc.) and is pretty quick. For the face to face interview, they usually focus mostly on tech knowledge and people skills. Be prepared to explain DNS as well as the difference between POP and IMAP. Any previous Linux (especially command line) experience is a big plus. On the personal end, basically they want to know how you deal with a difficult/angry customer.