Which of the following are valid OpenVPN authentication modes? (Choose TWO correct answers)

S/Key is an older one-time password authentication system and not a native OpenVPN authentication mode.

Kerberos is an authentication protocol, but it is not one of the primary, built-in authentication modes offered directly by OpenVPN; external integration would be required.

Static Key (pre-shared secret key) mode uses a single, shared key for both encryption and authentication between client and server, offering a simpler setup for peer-to-peer or small networks.

Password authentication can be used *in conjunction* with TLS, but TLS itself is the underlying authentication *mode* for client/server trust, not 'Password' as a standalone mode in the context of OpenVPN's primary options.

TLS (Transport Layer Security) mode uses X.509 certificates and Public Key Infrastructure (PKI) for robust authentication and key exchange, enabling secure and scalable VPN deployments.