Which expression confirms that all client certificates presented to the authentication vServer are valid through the year 2023?

• A. CLIENT.SSL.CLIENT_CERT.VALID_NOT_AFTER.EQ(GMT2023)
• B. CLIENT.SSL.CLIENT_CERT.VALID_NOT_BEFORE.EQ(GMT2023)
• C. CLIENT.SSL.ORIGIN_SERVER_CERT.VALID_NOT_AFTER.EQ(GMT2023)
• D. CLIENT.SSL.CLIENT_CERT.DAYS_TO_EXPIRE.EQ(2023)

Answer: (A)

The main idea is to verify the certificate’s expiration date to ensure it remains valid for the desired time window. The client certificate’s Not After date (VALID_NOT_AFTER) tells you when the certificate expires. By comparing this date to a fixed point representing the year 2023 (GMT2023) you’re constraining the certificates to expire within 2023, which means they would still be valid through the year 2023.

If the Not After date equals GMT2023, the certificate’s expiry falls in 2023, so the certificate is valid for the year 2023, satisfying the requirement for all client certificates presented to the authentication vServer.

Other options don’t fit as well because: the Not Before date would indicate when the certificate became valid, not when it expires; the origin server certificate is the server’s certificate, not the client’s; and DAYS_TO_EXPIRE gives a numeric countdown rather than a fixed expiry year, so it doesn’t directly confirm validity through 2023.