In this article I will briefly discuss how I conduct interviews for WebLogic Administration roles.
When conducting interviews I prefer to avoid difficult questions, and instead ask fairly simple questions and look at how well the candidate answers. I would prefer to hire someone who can clearly and concisely explain how to do a simple task than someone who knows every single thing about a particular technology.
I explain at the beginning of the interview, it’s acceptable if they are not able to answer every question; I use their answers to help decide if they will be a good fit for the team and the role.
Here are some of the questions I like to ask after I’ve given them a description of the role on offer.
- Which of your previous roles do you think have give you experience that could be important for this role?
- Tell me what is involved in a typical day in this role?
- Describe the kind of infrastructure you worked with in this role?
- On a scale of 1 to 10, with 1 being “no knowledge” and 10 being “know everything”, how would you rate your own skills? (I don’t look for people who think they “know everything”).
- What are some of the things you need to learn more about?
- If you were trying to access an application via a HTTP proxy and were getting a 404 error, how would you go about determining why you were getting this error?
- Describe how you would go about configuring a WebLogic server to give an application access to a database.
- How many threads does a managed server make available to an application? (expect different answers for different versions of WebLogic)
- What kind of problems would you expect to encounter when trying to increase a managed server’s maximum heap size to 3 GB? (Problems on 32-bit operating systems).
- If an application was suffering short periodic freezes, and no errors were appearing in the logs, can you suggest a possible cause? (Garbage collection)
- How could you prevent these periodic lock-ups?
- What are the ways you could check when garbage collection is occurring?
- If you start an admin server as a Windows service, where is that server’s classpath defined? (Windows Registry)
- If you start a managed server via a node manager, where is that server’s classpath defined? (config.xml)
- If a managed server is crashing with a StackOverflow exception, what could be the cause?
- Describe how you would go about configuring a JMS queue in a WebLogic cluster. (i.e. a distributed queue).
- Describe how you might run a WLST script?
Note it is also important to ask questions that determine if the candidate is familiar with best practices, such as Change Control and Configuration Management.