If a certificate expires, or soon will, you can reset the validity period. If an external certificate authority (CA) signed the certificate and the firewall uses the Online Certificate Status Protocol (OCSP) to verify certificate revocation status, the firewall uses the OCSP responder information to update the certificate status (see Configure an OCSP Responder). If the firewall is the CA that issued the certificate, the firewall replaces it with a new certificate that has a different serial number but the same attributes as the old certificate.