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

S/Key (one-time passwords) is not a native authentication mode directly supported by OpenVPN.

While OpenVPN might be integrated with Kerberos through external plugins, Kerberos is not a native, standalone authentication mode within OpenVPN itself.

OpenVPN can be configured to use a pre-shared static key (PSK) for authentication, which provides a simpler setup for point-to-point connections without requiring a Public Key Infrastructure.

While username/password authentication can be layered on top of a TLS connection in OpenVPN (e.g., using `auth-user-pass`), "Password" itself is not considered a primary mode of authentication in the same architectural sense as Static Key or TLS.

TLS (Transport Layer Security) is the most common and secure authentication mode for OpenVPN, where both client and server authenticate each other using X.509 certificates and keys as part of a secure TLS handshake.