When a web application is secured by the DualShield IIS Agent with MFA, the agent adds an extra layer of authentication over the web application's form-based authentication. Without Single-Sign-On enabled, users will be first authenticated by the DualShield SSO, then by the web application's original login process that's usually the user's AD credential verification.

You have 2 options:

  1. Configure DualShield SSO to verify the 2nd factor only, e.g. one-time-password etc, and keep the application's original login process which will verify the user's AD password. In this option. you do not need to enable Single Sign-On. 
  2. Configure DualShield SSO to verify both the 2nd factor and the user's AD password. In this option. you will need to enable Single Sign-On.  

From the security point of view, both options have no difference. However, from the user experience point of view, option 2 will deliver a more coherent user experience. 

Furthermore, DualShield IIS Agent provides 2 options for implementing Single Sign-On

Between Auto-Filling and Auto-Post options, Auto-Post is preferred as it is easier to set up and quicker in performance. However, some IIS web servers have such restrictions that it is not possible to enable Single Sign-On by Auto-Post

Single Sign-On by Auto-Post

Single Sign-On by Auto-Filling