The firewall can use three multi-factor authentication methods to authenticate access to the firewall: SMS, user certificate, and one-time password. These methods can be used in combination with other authentication factors, such as username and password, to provide stronger security for accessing the firewall web interface or CLI. The firewall can integrate with various MFA vendors that support these methods through RADIUS or SAML protocols5. Voice and fingerprint are not supported by the firewall as MFA methods. References: MFA Vendor Support, PCNSE Study Guide (page 48)