How does AD FS work?

Rebeladmin Inc. is an IT service provider. There are many customers who use different IT and cloud-based services from the company. Recently, the company introduced a new web-based control panel where customers can access their resources. The same application is also used by internal staff to manage the infrastructure services. Rebeladmin Inc. uses Active Directory Domain Service (AD DS) to manage identities. When a member of internal IT staff logs in to the portal, it doesn't ask for any login details. This is because the web application uses Integrated Windows Authentication (IWA) to allow access. This is also called NTLM authentication or domain authentication. It doesn't prompt for the login information initially, or transfer hashed data about the currently logged-in user to the web server to check whether it's allowed. This web server is...