What is the purpose of checking the CRL during SMTP authentication on a Cisco ESA?

Question

Options

• ACheck if the certificate is not revoked.
• BConfirm that corresponding CA is present.
• CVerify the common name matches user ID.
• DValidate the date to check if the certificate is still valid.

• A
  92% (23)
• C
  4% (1)
• D
  4% (1)

Explanation

A Certificate Revocation List (CRL) is a list published by a Certificate Authority (CA) that contains the serial numbers of certificates that have been revoked before their scheduled expiration date - for example, due to key compromise or the certificate being issued in error. When Cisco ESA performs TLS/SMTP authentication and receives a certificate from the remote party, checking the CRL allows the ESA to confirm that the certificate has not been revoked and is still considered valid by the issuing CA. This is distinct from other certificate checks: verifying the CA's presence confirms the issuer is trusted; verifying the common name checks identity matching; and checking the validity period confirms the certificate has not expired. The CRL check specifically addresses revocation status.

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