I was once asked on an interview what do you know about Linux? Of course, I responded with the answer that I can get around the OS pretty well. I am a long time Windows Server person like many of you out there. But the simple truth is that when you work as an IT Director or a Network Administrator you have to work in many types of server environments.
I was asked once in another interview years ago what I knew about Novell Netware? My response was that I have never seen Novell but I have heard of it. I then followed up with if they had a book lying around I am sure I can do what they needed me to do with the OS. Well, I got the job and my first day they wanted me to create some file shares. They handed me a book on Novell and within an hour I came back and said the file shares were ready to use.
What I have told many interns that I have trained over the years is that you can never be scared of any Server OS. Every time you come upon a new system go into it as a learning experience. Also if you can go home and set up a VM with the OS and begin poking around. And when you are learning to take the time to take notes on what you learned, they will come in handy down the road.
Once you do get the feeling for a new Server OS is to remember to revisit it and keep brushing up on your skills. You never know when you might take an interview and be asked questions about one of these systems.