Red Hat/CentOS/Linux in General Questions I may be asked in an interview

SrSysAdmin

I have an interview a week from Tuesday for a position where I would be the senior Sys Admin for a company which currently uses a hybrid of Windows and Red Hat servers.

Currently I'm the Jr Sys Admin (as the name implies) in an environment which uses Windows and CentOS. From what I understand, CentOS is pretty much exactly the same as Red Hat except that it's free and there is no official support for it.

My Windows skills are pretty good so I don't think I need to worry too much about that, however I need to brush up on my Linux skills. What sort of questions have you guys gotten about Linux in technical interviews you've been to in the past?


Thanks!

NightShade03

Well I would say it depends on how heavily they use each platform in the environment. Most of the time they will want to know that you can troubleshoot your way through problems. Topics/questions that I have been asked during an interview:

Process management (ps, top, grep)
Resource management (IRQ/memory/disk drives)
Disks (LVM/RAID)
Managing Users and Groups
SSH (This is usually a big one with linux for remote management)
Server builds (via NFS and kickstart)

darkerosxx

The interviews I've had for Linux/Unix positions have all been surprisingly light on OS questions and heavy on operational theory questions.

Some of the questions I was asked specific to OS involved how I would go about fixing a problem (general, nothing specific, so what log files would i begin looking at) and how to use specific programs that were used daily at the position. To counter that, I would spend plenty of time having someone break your OS and fix it, as well as learn as much about the position as you can, so you know what they work with. Even if you've been working with it for a while... break/fix refreshes your memory so you can respond quick.

If you can, find out more about how they're using Red Hat and you can likely have your answers ready. If you're dealing with HR, they'll ask you dummy linux questions (do you know command-line? which is a wtf question). If you're dealing with an experienced manager that cares about your skill, they'll ask you questions about what they do, in most cases, so knowing the position is critical.

MentholMoose

I had an interview where I had to explain the process of configuring, building and installing a custom kernel. During another interview I had to answer some basic troubleshooting steps, like identifying commands to use for certain tasks (e.g. how to check CPU/memory/disk usage, etc.).

SrSysAdmin

Do you guys know of any sites with a database of questions I can study? I have a week or so to study for this interview and would like to really nail it.

My last technical interview, I bombed the Linux part. I use Linux on a daily basis, but I'm not yet able to instantly recall things like I am with Windows. I haven't come across anything that I haven't been able to successfully complete at work yet, but I still have to look a lot up.

I've been thinking about doing the Linux+, guess I need to get on that.

NightShade03

These should get you started:

Unix Interview Questions and Jobs
Linux interview questions and answers - Linux FAQs

Amazon.com: Conducting the UNIX Job Interview: IT Manager Guide…
Amazon.com: Linux Interview Questions: Open Source Linux Operating Systems Interview Questions, Anwers, and Explanations (9781933804491): ITCOOKBOOK: Books

Chris:/*

To be quite honest you should really brush up your Linux skills instead of studying questions an HR person might not be able to tell the difference but an admin will. In addition I have know a number of guys who have gotten fired because they misrepresented their skills in the interview. Download virtual box and CentOS and run through some tests.

These books are great primer books if you cannot afford or do not have the time for a formal class. I included the Unix Book as well because most environments have some flavor of Unix running in a closet somewhere. As a notion some things about Linux are not covered in a Linux book but may be present in a Unix book.

Linux Administrator HandBook:
Amazon.com: Linux Administration Handbook (2nd Edition)…
Unix Administrator Handbook:
Amazon.com: Linux Administration Handbook (2nd Edition)…

Some Questions I ask possible inductees:

Q: What command will show you the hostname and version number of the kernel?
A:uname –a
Justification: You should always know where you are before you start administrating a system. Also bonus points would be given if you know the actual arguments.

Q: What file tells the version of red hat you are running?
A: /etc/redhat-release
Justification: This applies to patching, security and software compatibility lists.

Q: What command will give an equivalent output of ifconfig –a if ifconfig is not available?
A: netstat –ie or netstat –ei
Justification: Typically you deactivate ifconfig from being used by all but root because of security concerns. A user can actually change network settings if you are not careful.

Q: What command should you use to read a file from a data integrity stand point?
A: more or less not cat
Justification: cat being used carelessly can cause data to be changed or overwritten. Typically this command is also deactivated for the standard user.

SrSysAdmin

Chris:/* wrote: »

To be quite honest you should really brush up your Linux skills instead of studying questions an HR person might not be able to tell the difference but an admin will. In addition I have know a number of guys who have gotten fired because they misrepresented their skills in the interview. Download virtual box and CentOS and run through some tests.

These books are great primer books if you cannot afford or do not have the time for a formal class. I included the Unix Book as well because most environments have some flavor of Unix running in a closet somewhere. As a notion some things about Linux are not covered in a Linux book but may be present in a Unix book.

Linux Administrator HandBook:
Amazon.com: Linux Administration Handbook (2nd Edition)…
Unix Administrator Handbook:
Amazon.com: Linux Administration Handbook (2nd Edition)…

Some Questions I ask possible inductees:

Q: What command will show you the hostname and version number of the kernel?
A:uname –a
Justification: You should always know where you are before you start administrating a system. Also bonus points would be given if you know the actual arguments.

Q: What file tells the version of red hat you are running?
A: /etc/redhat-release
Justification: This applies to patching, security and software compatibility lists.

Q: What command will give an equivalent output of ifconfig –a if ifconfig is not available?
A: netstat –ie or netstat –ei
Justification: Typically you deactivate ifconfig from being used by all but root because of security concerns. A user can actually change network settings if you are not careful.

Q: What command should you use to read a file from a data integrity stand point?
A: more or less not cat
Justification: cat being used carelessly can cause data to be changed or overwritten. Typically this command is also deactivated for the standard user.

Like I said, I use CentOS on a daily basis at my current job without any issues. I have successfully setup LDAP integration on them so they all use Windows authentication, and rebuilt all the 32-bit OS systems as 64-bit...so it's not like I'm misrepresenting anything. I just don't know Linux as well as I know Windows, which is exactly what I told HR during that portion of the interview. My expertise is on the Windows side of things but I do have experience with Linux.

In any case, you guys posted some really great advice and I appreciate that, thanks for the helping hands!

Chris:/*

JrSysAdmin wrote: »

Like I said, I use CentOS on a daily basis at my current job without any issues. I have successfully setup LDAP integration on them so they all use Windows authentication, and rebuilt all the 32-bit OS systems as 64-bit...so it's not like I'm misrepresenting anything. I just don't know Linux as well as I know Windows, which is exactly what I told HR during that portion of the interview. My expertise is on the Windows side of things but I do have experience with Linux.

In any case, you guys posted some really great advice and I appreciate that, thanks for the helping hands!

Your post sounded like you were not confident in your knowledge level with Linux. Sorry to postulate incorrectly.

Best of luck getting your next job.