What is the difference between TLS and mTLS?

• A. TLS is deprecated; mTLS is current.
• B. In both, the client validates the server's certificates. In only mTLS does the server validate the client certificates.
• C. TLS validates the client; mTLS validates both directions the same.
• D. TLS uses certificates; mTLS uses passwords only.

Answer: (B)

The key idea is how authentication is handled during the TLS handshake. In standard TLS, the server presents a certificate and the client verifies it to ensure it’s talking to the right server. The client authentication part is optional, so the server doesn’t necessarily validate a client certificate. Mutual TLS changes that by requiring the client to present its own certificate and by the server validating that certificate as well as the client validating the server’s certificate. In other words, both sides authenticate each other, establishing two-way trust.

That’s why the correct choice describes that the client validates the server’s certificate in both cases, but only in mutual TLS does the server validate the client’s certificate. The other statements aren’t accurate: TLS isn’t deprecated and remains in use; TLS doesn’t rely on passwords only for authentication; and mutual TLS specifically adds client certificate validation, not just “same” validation in both directions.