add two more notes to switching certificate type

Author: jessie-jyy

articles/frontdoor/standard-premium/how-to-configure-https-custom-domain.md

@@ -131,7 +131,7 @@ In order for the certificate to be automatically rotated to the latest version w
 
 If you want to change the secret version from ‘Latest’ to a specified version or vice versa, add a new certificate. 
 
-##### How to switch between certificate types
+### How to switch between certificate types
 
 1. You can change an existing Azure managed certificate to a user-managed certificate by selecting the certificate state to open the **Certificate details** page.
 
@@ -141,7 +141,9 @@ If you want to change the secret version from ‘Latest’ to a specified versio
 *Bring Your Own Certificate (BYOC)*. Then follow the same steps as earlier to choose a certificate. Select **Update** to change the associated certificate with a domain.
 
     > [!NOTE]
-    > It may take up to an hour for the new certificate to be deployed when you switch between certificate types.
+    > * It may take up to an hour for the new certificate to be deployed when you switch between certificate types.
+    > If your domain state is Approved, switching certificate type between BYOC and managed certificate causes zero downtime. While switching to managed certificate, unless the domain ownership is revalidated and the domain state becomes Approved, you will continue to be served by the previous certificate.
+    > If you switch from BYOC to managed certificate, domain revalidation is required. if you switch from managed certificate to BYOC, there is no need for a domain re-validation.
     >
 
     :::image type="content" source="../media/how-to-configure-https-custom-domain/certificate-details-page.png" alt-text="Screenshot of certificate details page.":::