Subdomain validation in a different tenant

Question

Hi,

We have the following situation:

EntraID tenant 1

It contains a custom domain bbb.ccc.com which is hosted by a DNS zone in this same tenant.

The domain is verified in this tenant.

EntraID tenant 2

We must add and verify a custom domain here named AAA.bbb.ccc.com

After creating such custom domain in this tenant, we got the TXT record (MS=ms12121212) and were asked to add it to the DNS zone in "EntraID tenant 1".

Should this work?

We waited almost 24h and still not able to verify the domain in EntraID tenant 2.

There is one remark though: in the DNS zone in "EntraID tenant 1", there was an existing TXT record with a MS entry already there(MS=ms11111111), most likely from the days when we validated the "bbb.ccc.com" domain. To validate the second domain ("AAA.bbb.ccc.com"), we added an extra MS entry (MS=ms12121212) to that same TXT record, keeping the old one still there. Could this the reason for the failure?

Answer 1

Hi @PauloCosta55

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

Should this work?

Yes. As per the Microsoft document If you have already added a contoso.com domain to one Microsoft Entra organization, you can also verify the subdomain europe.contoso.com in a different Microsoft Entra organization. When adding the subdomain, you are prompted to add a TXT record in the Domain Name Server (DNS) hosting provider.

Refer this doc:

https://learn.microsoft.com/en-us/entra/identity/users/domains-manage

I hope it helps.

Thanks,
Rohith