11 job interview questions for virtualization engineers

Understand the virtualization engineer's role

Virtualization engineers handle a wide range of everyday tasks within the data center that focus on server configuration, storage and data management, and network configuration. This broad suite of tasks largely overlaps with the responsibilities of system administrators or system engineers, but they concentrate on tasks that involve or require a virtualization software, such as Microsoft Hyper-V or VMware vSphere.

A typical virtualization engineer is involved in VM setup, configuration, management or troubleshooting. They can configure, monitor or troubleshoot a virtual network, create or manage a storage instance or migrate data between multiple storage instances.

Virtualization engineers have strong analytical, problem-solving and communication skills. It's a perfect skill set to fix problems and provides support for IT automation tasks. Engineers are often involved with monitoring virtualization activities and producing reports on virtualized resources, resource utilization and resource performance.

 This role encounters a vast assortment of tasks and responsibilities including the following:

• handle physical-to-virtual projects to implement virtualization on legacy physical systems;
• create VMs and install Windows or Linux server OSes on those VMs;
• create and manage virtual desktops for virtual desktop infrastructure;
• use management tools such as System Center Configuration Manager to deploy VM packages or virtual desktops;
• configure and manage VPN connections;
• install and manage security measures, such as SSL encryption in VPNs;
• configure network-attached storage shares from filers;
• configure network file system and common internet file system storage shares to Unix and Windows clients;
• configure and manage iSCSI storage systems;
• support automation through PowerCLI script creation for routine tasks, such as ESXi host compliance reports or audit tracking;
• provide training to users and staff on new applications, services or resources; and
• create and update policies, practices and processes for virtualization and virtualized resource management.

Most virtualization engineers hold at least a Bachelor of Science in a computer-related discipline such as electrical engineering, computer science or information technology. Employers typically look for at least two years of experience in server management, storage management, systems administration or systems engineering.

Candidates can strengthen their job search with expertise of major virtualization offerings, such as Hyper-V or vSphere and current certifications from the corresponding vendor. A formal college degree is not always necessary to become a virtualization engineer, but the absence of a degree may demand additional experience and practical knowledge.

Typical virtualization engineer interview questions

Once IT professionals line up an interview for a virtualization engineer role, they  wonder what kinds of questions they'll face. Applicants should trust their virtualization experience and think about common questions asked during this type of interview.

Describe your overall virtualization experience.

This kind of question serves three purposes. It's an easy-sounding question to relax a candidate and get them to talk; it helps gauge the candidate's ability to communicate in an effective and focused manner; and it offers an early map into the candidate's technical strengths and weaknesses.

Honest, direct and efficient replies are the best response, but stay brief and let the interviewer move on to specifics.

Why have you deployed virtualization?

This is another introductory question to measure a candidate and evaluate their prior use cases for virtualization technology. Answers typically include common virtualization benefits or use cases such as cost reduction, better hardware usage, improved facility efficiency and better business agility through faster application deployment and mobility. Candidates might discuss past or current virtualization projects and initiatives.

What are the parts of [a certain hypervisor's] infrastructure?

At this point, an interviewer may start to dig a bit deeper into the candidate's virtualization knowledge of major hypervisors such as vSphere, Hyper-V or Citrix. This question gauges knowledge of what's involved in virtualization environment setup and maintenance. Don't worry if the interviewer uses a different hypervisor -- describe the most familiar infrastructure. Much of that knowledge is easily transferable to other hypervisors. The idea is that candidates can demonstrate a clear understanding of a hypervisor.

Describe or explain [X features] related to virtualization or a hypervisor.

The interviewer uses this question to gauge a candidate's knowledge in more detail. A candidate might be asked to describe or discus common features such as VM cloning, live migration, a use of memory and storage virtualization pooling, VMware distributed resource scheduler, the role of QEMU or the use of virtual volumes. Demonstrating a clear understanding of just a few features is often enough.

What is host isolation and fault tolerance, and why are they used?

High availability is often a vital attribute of virtualization environments, and virtualization engineers should have a solid understanding of hypervisor support for high availability. Host isolation is a common VMware use case for this attribute.

High availability carries small potential downtime since it can take minutes for the hypervisor, load balancer and other system components to detect the lost connection and restart the afflicted VM.

Fault tolerance is different than high availability. It spreads workloads across multiple hosts. Problems that might disable one host -- or even an entire cluster -- cannot impact all fault tolerance locations. This helps improve workload availability to almost 100%.

What types of virtualization have you deployed or managed?

This is another question to gauge a candidate's understanding and experience with virtualization technology. There are generally six types of virtualization, including user, hardware, application, desktop, network and storage. While the underlying use of hypervisors and abstraction do the same job, the purpose and goals of each virtualization type can offer different use cases and benefits to the business.

How do you set up and virtualize a typical server?

The common technical question is about the use of virtualization to create and configure a typical virtual server. The process typically includes selecting an appropriate physical server with adequate compute and memory resources; verifying the storage resources for virtual server images; using the hypervisor to create the virtual server; configuring the new virtual server with the desired security, connectivity and operating system; and setting up any failover or availability features needed to support the VM.

How would you perform [X] functions using vSphere, Hyper-V or Horizon?

These are some of the most specific and hands-on questions that an interviewer might ask a virtualization engineer candidate. The idea is to evaluate a candidate's specific know-how and validate their expertise with key processes and tools.

The actual function can include simple tasks, such as VM setup or VM snapshot capture, to more complex tasks, such as VMware direct resource scheduler deployment, data migration, or high availability or fault tolerant clusters setup. Another aspect to such questions is the use of policy and process – or how the candidate follows company policies and adheres to security standards.

What was the toughest virtualization problem that you ever had to troubleshoot, and how did you handle it?

Once an interviewer enquires about the candidate's basic knowledge, they often focus on advanced topics, such as troubleshooting. Virtualization engineers have a strong knowledge of virtualization tools and techniques, but they are also expert problem solvers that frequently tackle complex system, infrastructure and application problems. These types of questions can go in several different directions, but there is really no wrong answer here.

What metrics do you gather and log, and how did you set up reporting and alerting?

Virtualization engineers frequently employ alerts to recognize and categorize problems, logs to help identify and isolate issues within the virtual infrastructure, and reports to outline the environment status and spark discussions for upgrades or expansion. Candidates should have a strong knowledge of popular virtualization-compliant management tools and understand how to access and use the management information that reporting tools offer.

As one example, an interviewer might ask about fault tolerance logging and how it's used to support two ESXi hosts configured for fault tolerance operation. The conversation might also include the use of specific metrics, such as processor and memory usage or processes for custom metric implementation.

Given [a certain scenario and current infrastructure], what changes or upgrades would you recommend?

Virtualization engineers are often involved in infrastructure evaluations in order to support changes and upgrades that can enhance virtualized infrastructure and benefit the business. An interviewer may pose several general scenarios and challenge the candidate to spot possible problems or recommend useful changes that could resolve or improve the situation.

The scenarios are often general, and the fixes are usually simple. The goal is to evaluate a candidate's ability to understand the environment in the moment and have enough virtualization technology expertise to formulate a recommendation worth exploring.