An IT Security Compliance Auditor is assessing which nonfunctional requirements (NFRs) are already being implemented...

Understanding Nonfunctional Requirements (NFRs):

The NFRs in this context are related to security measures implemented for the Web API, such as rate limiting, LDAP-based authentication, JSON threat protection, and IP allowlist policies.

Evaluating the Options:

Option A (Correct Answer): The IP allowlist policy restricts access to known subnets, ensuring that API invocations come from a defined range of IPs.

Option B (Correct Answer): Basic Authentication with LDAP enforces a username/password validation, satisfying an NFR for identity verification.

Option C: Masking sensitive data is not part of the listed NFRs, as none of the mentioned policies address data masking.

Option D: XML threat protection is not mentioned, so this option is incorrect.

Option E: While rate-limiting implies performance control, it does not directly enforce a specific performance expectation.

Conclusion:

Options A and B are correct as they directly address the implemented security measures related to IP range restrictions and username/password authentication.

Refer to MuleSoft's documentation on API security policies for details on LDAP, rate limiting, and allowlist policies.