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.
 
Non-Technical Questions
  • 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?
 
Technical Questions
  • 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?
 
Other Questions
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.