There is a phone screening when you first apply for the Linux Technical Support position, the phone call lasts around 30 minutes. Some of the questions include customer support and Linux questions. The linux questions vary levels, you will have to explain what some commands do and the different types of distributions of linux available. If you pass the screening you will go to the onsite interview.
The Interview at the office consists of two rounds, one round with the department managers and the second round with the technical staff or supervisors.
Technical interview is there to get a gauge what level of tech you are.
If you want to do well make sure you know your LAMP stack and Linux admin commands.
Know the following:
DNS, ports, troubleshooting, MySQL commands, and service trouble shooting among others.
If you are certified in any Linux entry cert (CompTIA or Red Hat) you will do fine.
Have fun in the interview, the interviewers are great and want to find someone who fits in the culture.