A staple in OpenStack interview questions for experienced, be prepared to answer this one using your hands-on experience. Once you run instance in a virtualized environment, open new security controls that might be available while deploying onto bare metal. We can implement various technologies to the virtualization stack for improving the information assurance for cloud tenants.  The OpenStack users with strong security requirements must deploy these technologies. It might be possible that all technologies are not available for every scenario. Some technologies inspect instance data like run state that are not required by the users of the system. Different security services for instances are-  Entropy to instances.  Trusted images   Migration of instance  Update and patches  Monitoring, alerting, and reporting.  Firewalls and other security controls.