Cloud Shared Responsibility: OS Patching in IaaS vs PaaS
An organization is selecting a cloud architecture and does not want to be responsible for patch management of the operating systems. Why should the organization select either Platform as a Service or Infrastructure as a Service for this environment?
Community Insight
The exam often traps candidates on who owns the OS; remember that in PaaS, the vendor manages the OS stack, whereas in IaaS, the customer does.
This question tests the cloud shared responsibility model, specifically who manages operating system patching. Platform as a Service (PaaS) is the correct choice because the provider handles the underlying OS.
Candidates frequently choose Infrastructure as a Service (IaaS), mistakenly believing that moving to the cloud automatically offloads all infrastructure management, including the guest OS.
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Expert Analysis
Why the Answer Is Correct
Platform as a Service (PaaS) provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app. In a PaaS model, the service provider manages the hardware, operating system, middleware, and runtime, leaving the customer to focus solely on the application data and code. Therefore, if an organization wants to avoid OS patching, PaaS is the ideal selection.Why the Other Options Are Wrong
Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet. While the provider manages the physical hardware and hypervisor, the customer is responsible for managing the guest operating system, including security patches and updates. Options claiming the provider manages the OS in IaaS are factually incorrect regarding the standard shared responsibility model.Community Comment Notes
Community feedback confirms this distinction. As one commenter noted, "PaaS builds on the IaaS model... Cloud providers... host and manage operating systems." This reinforces that PaaS abstracts away the OS layer for the consumer.Exam Strategy
Memorize the boundary lines between IaaS, PaaS, and SaaS. A good rule of thumb is that as you move up the stack from IaaS to SaaS, the customer's responsibility decreases. If the question asks about avoiding OS management, look for PaaS or higher.
Frequently Asked Questions
Does IaaS ever include OS patching?
No, in standard IaaS, the customer is responsible for the guest OS patching. Some managed services exist, but they are not standard IaaS.
What does the provider manage in PaaS?
The provider manages the physical hardware, virtualization layer, operating system, and middleware. The customer manages the application and data.