The System.Security.Authentication.ExtendedProtection.ExtendedProtectionPolicy is always enforced. Clients that don’t support extended protection will fail to authenticate.
Syntax
PolicyEnforcement Always
Requirements
Namespace: System.Security.Authentication.ExtendedProtection
Assembly: System (in System.dll)
Assembly Versions: 4.0.0.0
Assembly: System (in System.dll)
Assembly Versions: 4.0.0.0