Types of Authentication

[SAP Online]

There are two types of authentication

one step authentication
two steps authentication

In two steps authentication verification of two resources is required

[davidsmith21]

There are three types of authentication.
1. The first type of authentication is accepting proof of identity given by a credible person who has first-hand evidence that the identity is genuine.
2. The second type of authentication is comparing the attributes of the object.
3. The third type of authentication relies on documentation or other external affirmations.

[Mywebbee]

There are three common factors used for authentication:

Something you know (such as a password)
Something you have (such as a smart card)
Something you are (such as a fingerprint or other biometric method)

[jerryperes]

Are you talking about asp.net authentication or something else? Firstly confirm, then I will let you know about this