Which NSX-T built-in role is the most restrictive while still allowing a user to apply configuration changes on a NSX Edge?

The most appropriate choice for a role that is both restrictive and allows a user to apply configuration changes on an NSX Edge is the Network Engineer role. This role specifically enables users to make configuration changes related to network functions without granting broader administrative privileges that come with other roles.

The role provides targeted permissions that allow operational management of the network infrastructure. Users assigned this role can perform various configuration tasks on NSX Edge devices, such as creating or modifying logical switches, routers, and firewalls, while ensuring that their access is limited in scope to prevent unintentional or unauthorized changes to the overarching NSX environment.

In contrast, roles such as the NSX Administrator offer comprehensive permissions and can manage the entire NSX environment, which would be less restrictive than what is aimed for in the context of this question. The Cloud Service Administrator role focuses on managing cloud service capabilities rather than specific edge configurations. The Network Operator role generally has read-only access or limited configuration capabilities, making it less suitable for tasks that involve applying changes on NSX Edge directly.

Thus, the Network Engineer role strikes the right balance, allowing necessary configuration permissions without overextending user capabilities within the NSX environment.