Which one of the following is associated heavily with vendor lock-in?

Concept: Cloud service models sit on a spectrum of who manages what. The less infrastructure a vendor manages and the more freely portable the workload, the lower the vendor lock-in; the more an application is built directly against a vendor's own proprietary platform (its APIs, managed services, runtime), the higher the lock-in.

Application: Building on PaaS means writing and deploying code against that vendor's own runtime, managed database/messaging services, and deployment tooling. These proprietary interfaces are rarely compatible across providers, so moving an application from one PaaS platform to another typically forces a substantial rewrite — this is exactly the dependency that defines heavy vendor lock-in.

Contrast with the other options:

• DaaS: delivers virtual desktops on demand; the dependency is on a consistent desktop experience, not on writing application code against a vendor's platform APIs, so it carries a much lighter technical lock-in.

• SaaS: delivers a complete, ready-to-use application; the customer never writes code against the vendor's platform at all, so switching mainly means exporting data and retraining users, not rewriting an application.

• IaaS: provides raw virtualized compute, storage, and networking behind fairly standardized interfaces (VM images, containers), so workloads can be redeployed on another provider with comparatively modest reconfiguration.

Result: because PaaS ties the developed application itself to one vendor's proprietary platform, it is the cloud service model most heavily associated with vendor lock-in among these four.