A. Malicious IP addresses. B. Trusted CA’s. C. Untrusted private keys. D. Public keys.
Explanation: A certificate revocation list (CRL) is created and distributed to all CAs to revoke a certificate or key. By checking the CRL you can check if a particular certificate has been revoked. The certificates for which a CRL should be maintained are often X.509/public key certificates, as this format is commonly used by PKI schemes.