In an IaaS environment, what is the proper way to apply a list of OS patches?

In an Infrastructure as a Service (IaaS) environment, applying OS patches effectively requires a strategic approach that minimizes downtime and disruption. The correct answer involves identifying the hypervisor type, selecting a group of instances, and performing a rolling application of patches.

This method is beneficial because it allows for continuous availability of services while patching. By applying patches in a rolling fashion, only a subset of instances is taken offline at a time, ensuring that the overall service remains available to users. This is particularly crucial in cloud environments where uptime and reliability are top priorities.

Additionally, understanding the type of hypervisor in use can influence how patches might be applied, especially since different hypervisors can have varying capabilities and limitations regarding the virtualization and maintenance of guest operating systems. Using this approach also helps to ensure that all virtual machines are aligned to the same configuration, reducing the risk of inconsistencies.

In contrast, focusing on the guests, applications, or services individually could lead to increased downtime and complexity, as it does not take advantage of the efficiencies gained by managing multiple systems at once, nor does it provide a streamlined way to handle patching across a larger environment effectively.