A user attempting to log on to a workstation for the first time is prompted for the following information before being granted access: username, password, and a
four-digit security pin that was mailed to him during account registration. This is an example of which of the following?

A.
Dual-factor authentication

B.
Multifactor authentication

C.
Single factor authentication

D.
Biometric authentication

Explanation:
Multi-factor authentication (MFA) is a method of computer access control which a user can pass by successfully presenting authentication factors from at least two
of the three categories:
knowledge factors (“things only the user knows”), such as passwords possession factors (“things only the user has”), such as ATM cards inherence factors (“things
only the user is”), such as biometrics
In this question a username, password, and a four-digit security pin knowledge are all knowledge factors (something the user knows). Therefore, this is singlefactor authentication.
Incorrect Answers:
A: Dual factor authentication uses two factors of authentication. There are three main factors of authentication: knowledge factors, possession factors and
inherence factors. In this question, only one factor (knowledge factor) is being used.
B: Multi-factor authentication uses more than one factor of authentication. There are three main factors of authentication: knowledge factors, possession factors
and inherence factors. In this question, only one factor (knowledge factor) is being used.
D: Biometric authentication is an inherence factor something specific to the user such as a fingerprint or a retina scan. Neither are being used in this question.

http://en.wikipedia.org/wiki/Multi-factor_authentication