The Transport Layer Security (TLS) protocol creates a secure communications channel over public media (such as the Internet). In a typical TLS session, what is the usual means for establishing trust b

Out-of-band authentication involves using a separate communication channel for verification, which is not the primary mechanism for establishing trust in the TLS handshake.

Multifactor authentication requires multiple credentials for user login but is not the method by which communicating systems establish trust within the TLS protocol itself.

During the TLS handshake, the server presents its X.509 digital certificate, which contains its public key and is digitally signed by a trusted Certificate Authority (CA). The client verifies this certificate's authenticity and validity through the Public Key Infrastructure (PKI), thereby establishing trust in the server's identity before encrypting communications.

Preexisting knowledge of each other is not a scalable or general mechanism for establishing trust in TLS sessions across the public internet; PKI certificates provide this universal trust anchor.