Your customer has an external system, which is used to perform changes. Your customer wants to capture these changes in your instance for reporting and CMDB maintenance purposes. What baseline…

Automated Changes represent changes executed by automated processes within or directly integrated with ServiceNow, not changes originating from a separate external system that needs to push records in.

Cloud Infrastructure is not a baseline Change Model in ServiceNow's Change Management module; it refers to an infrastructure category, not a change workflow.

Unauthorized Changes are used to document changes that were made without any approval or record, typically as a compliance or audit response, not as a structured integration mechanism for an external system.

Change Registration is the baseline Change Model built to record changes that originate outside of ServiceNow - for example, from third-party automation or external ITSM tools. It creates a change record in the instance after the fact so the CMDB reflects the actual configuration state and reporting remains accurate. This model is purpose-built for the integration scenario described, where the source of the change is an external system.

Retroactive Changes are used when a change was performed without prior approval but still within the ServiceNow ecosystem; they differ from Change Registration, which is specifically for capturing externally originated changes.