An enterprise that runs numerous proprietary applications has major issues with its on-premises server estate hardware, to the point where business-critical functions are compromised. The enterprise…

SaaS (Software as a Service) delivers fully managed applications to end users, leaving no control over the OS or application layer, which conflicts with the requirement to control proprietary applications.

PaaS (Platform as a Service) abstracts OS and runtime management away from the customer, providing only an application deployment platform, so the enterprise would lose OS-level control.

IaaS abstracts physical hardware so the enterprise avoids hardware procurement, failure, and maintenance concerns while retaining administrative control over the OS, runtime, and proprietary applications. This directly addresses both problems stated: hardware issues are eliminated and application/OS control is preserved. It is the appropriate model when the enterprise needs to manage its own software stack without owning physical infrastructure.

Hybrid cloud is a deployment model describing a mix of on-premises and cloud environments, not a distinct service model that resolves hardware issues while guaranteeing application and OS control on its own.