In an IaaS model, while the cloud provider is responsible for the physical infrastructure, networking, and virtualization, the client is responsible for managing the operating system, storage, and applications. As such, patch management for the operating system falls under the client's responsibility. It's a common misconception that the cloud provider would manage this aspect in IaaS, but they only manage the underlying infrastructure layers. Additionally, physical network controls and hypervisor configuration are managed by the provider, not the client, which can lead to confusion.