Which authentication approach requires two or more independent factors to verify a user's identity?

Which authentication approach requires two or more independent factors to verify a user's identity?

• A. In-Band Authentication
• B. Out-of-Band Authentication
• C. RADIUS
• D. Multifactor Authentication (MFA)

Answer: (D)

Verifying identity with two or more independent factors strengthens security by requiring different kinds of evidence, so no single compromised factor unlocks access. This approach—multifactor authentication—draws from categories like something you know (a password), something you have (a token or phone), and something you are (biometrics). The key is independence and diversity of factors, ideally across different senses or channels, so compromising one factor doesn’t automatically reveal another. The other terms don’t commit you to multiple factors by themselves. In-band and out-of-band describe how verification is delivered or communicated, not necessarily that multiple factors are required. RADIUS is a protocol for handling authentication, authorization, and accounting, not an authentication model that enforces two or more independent factors.

Verifying identity with two or more independent factors strengthens security by requiring different kinds of evidence, so no single compromised factor unlocks access. This approach—multifactor authentication—draws from categories like something you know (a password), something you have (a token or phone), and something you are (biometrics). The key is independence and diversity of factors, ideally across different senses or channels, so compromising one factor doesn’t automatically reveal another.

The other terms don’t commit you to multiple factors by themselves. In-band and out-of-band describe how verification is delivered or communicated, not necessarily that multiple factors are required. RADIUS is a protocol for handling authentication, authorization, and accounting, not an authentication model that enforces two or more independent factors.