Certificate Revocation List (CRL) Reasons | CCIE Security Exam - Cisco

Reasons for Certificate Revocation

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Question

What are two reasons for a certificate to appear in a CRL? (Choose two.)

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A. B. C. D. E.

AB.

A certificate can appear in a CRL (Certificate Revocation List) for various reasons, including:

A. CA key compromise: If the private key of a CA (Certificate Authority) is compromised, an attacker can issue unauthorized certificates. In such cases, the CA should revoke all the certificates that were issued using that compromised key. This is to prevent further abuse of the certificates by attackers.

B. Cessation of operation: If an organization that issues certificates goes out of business, it may revoke all the certificates it has issued. This is to prevent the use of certificates by unauthorized entities after the organization has ceased to exist.

C. Validity expiration: Certificates have an expiration date, beyond which they are considered invalid. When a certificate expires, it should be revoked to prevent its use after the expiration date.

D. Key length incompatibility: This is not a valid reason for a certificate to appear in a CRL. Key length incompatibility is usually an issue during certificate validation, where a certificate's key length may not be compatible with the security policy of the application or system using the certificate. However, it does not require revocation of the certificate.

E. Certification path invalidity: This is also a valid reason for a certificate to appear in a CRL. When a certificate is part of an invalid certification path (for example, when a certificate in the chain is revoked or expired), it should be revoked to prevent its use in an insecure context.

In summary, the two reasons for a certificate to appear in a CRL are CA key compromise and cessation of operation, while validity expiration and certification path invalidity may also require revocation, but they are not the specific reasons for a certificate to appear in a CRL. Key length incompatibility is not a valid reason for revocation.