You are implementing SAP Customer Identity via a server-side REST API.

To start making API calls against your existing API key in SAP Customer Data Cloud using a server-side REST API, you need to:

A: Create a new application and generate a secret key. The secret key is required for authenticating API requests securely. The API key alone is insufficient for server-side API calls; the secret key ensures secure communication.

The other options are incorrect:

B: Creating a CNAME in the site settings is related to custom domain configuration, not API authentication.

C: Adding the IP address to the IP-Allowlist is optional and only required if IP restrictions are enabled. It is not mandatory for making API calls.

D: Enabling the REST interface in the site settings is unnecessary because the REST API is already enabled by default.

SAP Customer Data Cloud References:

API Authentication.

Creating Applications and Secret Keys.