What should you use to ensure that the members of an Azure Active Directory group use multi-factor authentication (MFA) when they sign in?

To ensure that members of an Azure Active Directory group use multi-factor authentication (MFA) when they sign in, a conditional access policy is the most appropriate choice. Conditional access policies are a key feature of Azure Active Directory that allow organizations to enforce various security controls based on specific conditions.

When you create a conditional access policy, you can specify criteria such as user group membership, the application being accessed, the location of the user, the device being used, and even the risk level associated with the sign-in attempt. By specifically designing a policy that requires multi-factor authentication for a particular group, you ensure that those users must complete an additional verification step (in addition to their username and password) during the sign-in process.

This capability is crucial for enhancing security, especially for access to sensitive applications or data. By incorporating MFA into the authentication process, organizations can significantly reduce the risk of unauthorized access due to compromised credentials, thereby strengthening their overall security posture.