What of the following is NOT an essential characteristic of cloud computing?

Broad Network Access is one of the five NIST-defined essential characteristics, referring to access over standard network mechanisms from heterogeneous client platforms.

Measured Service is one of the five NIST-defined essential characteristics, referring to metered resource usage that enables pay-per-use billing and monitoring.

Third Party Service is not included in the five essential characteristics defined by NIST SP 800-145. The five official characteristics are: on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. Cloud computing can be deployed as a private cloud operated entirely by the consuming organization, so being a third-party service is not essential.

Rapid Elasticity is one of the five NIST-defined essential characteristics, referring to the ability to provision and release resources quickly in proportion to demand.

Resource Pooling is one of the five NIST-defined essential characteristics, referring to the provider serving multiple consumers via a multi-tenant model with dynamically assigned resources.