Hiring good linux people can be tough. Lots of buzzwords, and only high level understanding are thrown around. I've composed a list of questions that should hopefully be able to dig through the buzzword interviewee and test their real knowledge. I've included the questions and not the answers... if you're asking the questions, you should already know the answers :)
Below is the list of questions I print out and take with me to help me remember what to ask, and note the answers they give. Feel free to post questions you ask, and I can add them to the list.
Personality
- Tell me about the last major Linux project you finished. What were some of the obstacles and how did you overcome them. Sometimes asking these open questions will reveal much more then small questions that are easily answered by Google. A great senior admin doesn't need to know everything, but they should be able to come up with amazing solutions to impossible projects.
- Do you contribute to any Open Source projects? Doesn't matter if it's just documentation, it shows a certain dedication to the craft
- Tell me about the biggest mistake you've made in [some recent time period] and how you would do it differently today. What did you learn from this experience?
Admin - Unix/Linux
- How do you check an executable for shared library dependencies?
- You routinely compress old log files. You now need to examine a log from two months ago. In order to view its contents without first having to decompress it ?
- What are the different run levels, and what happens at each?
- What is required to be running for a client to mount a NFS share?
- What's your favorite scripting language and why?
- How do you check for an installed package?
- How would you make a change on 100 hosts? 1000?
- How would you see what group/groups someone is a member of?
- If a client cannot connect to port 80 on a server, what would you do to troubleshoot? How would you be able to tell if the server was allowing connections to that port?
- How would you check if a file system was mounted readonly?
- What's the difference between UDP and TCP?
- What advantages does epoch time have over local time (zones or GMT/UTC).
- Describe the difference between static linked and dynamically linked binaries.
- Describe the difference between TCP and UDP protocols.
- Describe a TCP handshake.
- What protocol does ping use?
- Is ping reliable?
- Your network is getting DDoS'd, what do you do?
- Describe the difference between raid 0 1 and 5.
- What raid level would you typically use for the OS/root disk of a system.
- What command would you use to capture network traffic for analysis?
- How do you find out who owns a domain?
- What kind of storage devices do you have experience with?
- What kind of load balancers are you familiar with?
- Can you describe a VIP and what it does?
- What program would you use to copy entire directories from one machine to anothe r?
- What would you use to only copy files that have changed?
- What does it mean if you see a "connection refused" error in your logs and how i s that different from a "connection timed out" error?
- What does a "connection reset by peer" error indicate?
- What would you do to diagnose an Apache server that has stopped responding. You have shell access to the system and can't connect to Apache, even from localhost , but the process is running..
- How do you split strings on a command line? What commands would you pipe the out put to?
- How do you match any character in regex?
- How do you match the beginning of a line?
- How do you match the end of a line?
- In HTTP protocol, what does HEAD, GET and PUT do?
- What port does Oracle run on?
- What is the name of Oracle hosts file? The file where you define oracle DB names , IP addresses, and port numbers..
- You are getting errors saying the filesystem is full, but df shows plenty of spa ce available, what do you check?
- How do you check inode usage on a filesystem?
- In a shell, how do you redirect the output of a command?
- How do you redirect error (STDERR) output on a command line?
- What's the difference between SAN and NAS?
- You have a system that has been hacked in your datacenter.. You have physical ac cess to the system, what do you do?
- Describe the difference between FTPS and SFTP.
DNS TRIVIA:
- Describe how a DNS query works.
- Describe the parts of a DNS zone file SOA.
- What do you change after modifying a zone file, to make sure your changes take e ffect.
- Where are the root DNS servers defined?
- What is the TTL in DNS and what does it control?
- A domain does not have an MX record, where does the mail go?
- What protocols does DNS use?
- Why would DNS respond with TCP instead of UDP?
