Final answer:
The Azure service that should be used is Azure AD Conditional Access to prompt Azure AD users to change their password when connecting from the Internet with an anonymous IP address.
Step-by-step explanation:
The Azure service that should be used to prompt Azure AD users to change their password when connecting from the Internet with an anonymous IP address is Azure AD Conditional Access.
Azure AD Conditional Access enables organizations to apply policies to manage and control access to Azure resources based on specific conditions, such as user location, device type, and risk level. By configuring a Conditional Access policy, you can require Azure AD users to change their password when accessing Azure AD from the Internet using an anonymous IP address.
For example, you can create a Conditional Access policy that applies to users connecting from an IP address range known to be anonymous, and configure the policy to require users to change their password upon login. This way, users will be prompted automatically to change their password when accessing Azure AD from the Internet with an anonymous IP address.