July 29, 2015

10 Job Interview Questions for Linux System Administrators

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Job opportunities abound for system administrators and DevOps professionals who know Linux. But even sought-after, seasoned SysAdmins still have to go through the hiring process, from sending in a resume, to taking technical exams and meeting for interviews.

And while resumes and tests are important, they often serve as an efficient way to screen candidates before advancing them to what is, arguably, the more critical test: a job interview. It's in the interview process that a candidate is vetted for the personal qualities that will help determine if they're a good cultural fit for the company and an employee worth investing in.

SysAdmins of all experience levels, then, can benefit from brushing up on their job interview skills if they want to find and land a great new job.

“Interviewing for a job can be nerve-racking, especially when it's your first interview,” says Michele Casey, director of product management for Oracle Linux. “Just be well-prepared. That's the best thing you can do.”

Master the Interview Questions

A quick Internet search for “SysAdmin interview questions” will give you more than enough potential questions to practice with. Sites like Quora, Stack Overflow and this GitHub SysAdmin interview questions repository are good places to start.

But questions like, “Explain what happens when you type http:// into your browser,” have almost become cliché. Many skilled interviewers tend to skip over these common questions, and the basic technical underpinnings, in favor of deeper questions that not only show a candidate's level of knowledge, but reveal their personality. Such questions aim to suss out your approach to problem-solving, critical thinking skills, and how you react under pressure.

“I try to avoid asking the questions that are published out there, but not because I'm worried that someone will memorize everything. I want to make sure people are in situations where they need to think,” said Joe Smith, a senior site reliability engineer at Twitter. “Most of the time it's not going to be an easy solution.”

Here are some favorite interview questions from senior system administrators, IT managers, and human resources professionals who work at Linux Foundation member companies – some of the largest and most influential companies in the tech industry today. Each took a slightly different approach – some were much more technical than others. However, their reasons for asking were largely the same: find out who this candidate is, as a person, and how they think and reason through problems.

10 Favorite SysAdmin Interview Questions

1. What do you love about technology?

“I like for them to have an opportunity to share what they're passionate about, even if it has nothing to do with the job.” - Michele Casey, Director of Product Management, Oracle.

2. Name and describe a different Linux/Unix command for each letter of the alphabet. But also, describe how a common flush toilet works.

“The first question helps illustrate the breadth of their CLI chops. But just as important is describing how a toilet works; it demonstrates their well-roundedness and/or ability to think, reason, and hypothesize on their feet.” - Michael Jennings, Computer Systems Engineer, Linux Server/Cluster Admin, Lawrence Berkeley National Laboratory.

3. What open source projects are you interested in?

“A really good candidate, even if they're junior will have found the project they're interested in and be committing a bit back or writing some documentation. They will be really plugged into what the open source community is doing. They'll have run Apache Zookeeper, for example. They'll have wrestled with the code and looked through the docs and actually understand how this works. And maybe they haven't run it in production but they understand at a high level how the pieces interact, how you can take advantage of it, and what the benefits are.” - Joe Smith, Twitter.

4. I have this server which seems to drop off the local net every so often, and comes back on its own. How would you debug this?

“I give them problems that I hope they don't already know to see how they work through them. I have a list of troubleshooting questions and guesstimate which one to use depending on the level of the candidate.” - Marc Merlin, Senior Linux Server Admin, Google.

5. How does TLS work?

“It helps me understand how good they are with security topics. How in-depth they go with their answer – how comfortable they are – tells me a lot.” - Konstantin Ryabitsev, Director of Collaborative IT Services at The Linux Foundation.

6. What do you know about SUSE, why do you want to work here, and what's the role of open source in the market?

“Candidates can show their motivation through concrete contributions or visibility in an open source community and an understanding of what companies do. They will have researched SUSE before they come and talk to us. The bare minimum is that they have installed openSUSE and actually played around with that.” - Marie Louise van Deutekom, SUSE's Global Human Resources Director.

7. What about this job appeals to you?

“That'll tell me how much they've thought about it. A.) You need to make sure you understand your strong points – know yourself. B.) Know what the job entails. And C.) make sure that when you speak you do it sincerely and honestly and be yourself. Probably the biggest mistake that people make is trying to put on a facade.” - Steve Westmoreland, Chief Information Officer, The Linux Foundation.

8. Tell me a "war story" about a situation that went wrong and what you did to help on your own initiative.

“In an interview I don't dive into "tech" skills. Coding languages and various packages can be learned. I am firmly of the belief that you learn a heck of a lot more about a candidate in an interview by asking him or her to tell you "war stories.” If they stumble on that, then you're looking at a Drone. (Next!)” - Tim Hoogasian, Solutions Project Manager at Newstar Digital and former Technical Project Manager at Dell.

9. Print the content of a file backwards.

“I like broad questions where each person could give a different answer depending on their depth of knowledge. My personal answer is 8 characters not including the filename.” - Marc Merlin, Google.

10. Nothing in particular.

“I don't have one question that everyone needs to know. If someone doesn't know the answer to something, that's great. We'll work through the problem and come to the answer together.” - Joe Smith, Twitter.

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