Federation with Azure AD
Federation trusts between domains allow organizations to manage their own identities within their own environments. Azure AD also supports federation with on-prem AD. When a federation trust is in place, users can log in to Azure AD using the same on-prem AD passwords. With this method, on-prem users will always be authenticating via on-prem AD. We can use AD Federation Services (AD FS) or PingFederate to create federation trusts between Azure AD and on-prem AD.
In Chapter 13, I have explained how AD FS works with Azure AD and also demonstrated how to enable federation between Azure AD and AD FS. Please check Chapter 13 if you need more details.
Pass-through authentication
To create federation trusts between Azure AD and on-prem AD, quite a bit of work is involved. We need additional servers, SSL certificates, licenses, a HA solution, firewall changes, and advanced configurations. But Azure AD Pass-through Authentication allows organizations to...