Final answer:
Preservation of metadata is not an essential characteristic of the cloud model set by NIST, unlike resource pooling, broad network access, and on-demand self-service.
Step-by-step explanation:
In the context of the cloud model, preservation of metadata is NOT an essential characteristic. The National Institute of Standards and Technology (NIST) outlines several essential characteristics of cloud computing, which include resource pooling, broad network access, and on-demand self-service. These features allow multiple customers to access computing resources that are available over the internet, and they can do so without human intervention from the service provider.