Friday, January 18, 2019

Recover custom DNS domains in deleted Microsoft Demos tenant

In the past Microsoft cloud consultants they are using the MS cloud demo platform are sometimes connecting their own DNS domains to the Office365 tenant. 

When they delete later the tenant (it typically runs for 90 days only!) and they want to reuse their custom DNS domain in another tenant then the old DNS name is still attached to the old deleted tenant! And they can not attach it to the new tenant anymore. 

But this can be fixed!

Here is how this works:

1. The old tenant is somehow deleted but not really completely. This means:
2. Login to with your custom name: e.g. still works. Same with Azure portal. But you can not use any services from it. Also the licenses are removed for the users.
3. Navigate to: SETUP -> Domains

4. Notice the name!
5. Logout
6. Login again with the - use your DNS name you noticed from your tenant instead!
7. Navigate again to: SETUP -> Domains
8. Click on your custom domain name e.g.
9. Now you see in the top menu the option to delete it.
10. Follow the instructions (e.g. which include to move the custom DNS mail addresses back to the Microsoft generic DNS entry)
11. Voila you have your custom DNS back for using somewhere else!
12. Now you can exit the admin portal.