diff --git a/windows/security/identity-protection/hello-for-business/hello-identity-verification.md b/windows/security/identity-protection/hello-for-business/hello-identity-verification.md
index bea20d5eec..83bb883504 100644
--- a/windows/security/identity-protection/hello-for-business/hello-identity-verification.md
+++ b/windows/security/identity-protection/hello-for-business/hello-identity-verification.md
@@ -73,3 +73,6 @@ The table shows the minimum requirements for each deployment.
 | Windows Server 2016 AD FS with [KB4088889 update](https://support.microsoft.com/help/4088889) | Windows Server 2016 AD FS with [KB4088889 update](https://support.microsoft.com/help/4088889) |
 | AD FS with Azure MFA Server, or</br>AD FS with 3rd Party MFA Adapter | AD FS with Azure MFA Server, or</br>AD FS with 3rd Party MFA Adapter |
 | Azure Account, optional for Azure MFA billing | Azure Account, optional for Azure MFA billing |
+
+>[!IMPORTANT]
+> For Windows Hello for Business deployment, if you have several domains, at least one Windows Server Domain Controller 2016 is required for each domain. For more information, see the [planning guide](https://docs.microsoft.com/windows/security/identity-protection/hello-for-business/hello-adequate-domain-controllers).