Unable to re-use a DNS name label in a different tenant

Polka Oliver 5

We are migrating our infrastructure from one tenant to a new tenant. We would like to have as little downtime as possible. We have a kubernetes cluster and using Public IP Addresses with assigned DNS name labels such as "service-name.westeurope.cloudapp.azure.com". We unassigned the DNS name label from the IP address in old tenant, and wanted to use the same name "service-name.westeurope.cloudapp.azure.com" in the new tenant. Unfortunately we receive an error saying:

"DNS name label not available. Try using a different label." We have moved our "Test" environment successfully couple of weeks ago, now we started with our "pre-prod" environment and have those issues. My first question is: What changed in the last couple of weeks that this was possible before and now suddenly we are not able to do it? My follow up question is: Is there some grace period that makes the DNS unavailable for some time? In case there is - how long is the grace period? Is there a way to go around it? Thanks for any feedback or pointers.

ChaitanyaNaykodi-MSFT 26,101 Reputation points Microsoft Employee

2023-04-17T16:27:55.0333333+00:00

@Polka Oliver

Welcome to the Microsoft Q&A forum.

If I understand correctly, you have unassigned the DNS name label from the IP address in old tenant but still are getting the error "DNS name label not available. Try using a different label."

Can you try running a nslookup command for the your domain above and see which public IP address it resolves to (Example for nslookup)

If the domain resolves to the old tenant's IP address, can you please check if the DNS name label is removed from the Public IPs configuration? You can find the configure option here on the portal

If the domain resolves to a new IP address, can you please check if the IP address belongs to your subscription. if it is already taken/used by another customer in the same region, it may not be available.

Please let me know if you need any help here. Thank you!
ChaitanyaNaykodi-MSFT 26,101 Reputation points Microsoft Employee

2023-04-20T03:29:24.7266667+00:00

@Polka Oliver Just following up here to see if you were able take a look at my comment above. Thank you!
Polka Oliver 5 Reputation points

2023-04-20T08:26:44.89+00:00
Hi, when I do nslookup after un-assigning the DNS label I'll get a following response:

nslookup <service-name>.westeurope.cloudapp.azure.com Server: 2a00:11b4:4110::a Address: 2a00:11b4:4110::a#53 ** server can't find <service-name>.westeurope.cloudapp.azure.com: NXDOMAIN

So it looks like it does not resolve to the old tenant's IP address, also it does not resolve to a different IP address that does not belong to us. In the new tenant I still can't assign it - will get the same error message. In the old tenant I can assign it to the same IP address or a different IP address with no issues.
ChaitanyaNaykodi-MSFT 26,101 Reputation points Microsoft Employee

2023-05-07T21:36:39.7066667+00:00

@Polka Oliver

Just checking in to see if the below answer helped. If this answers your query, please don’t forget to click "Accept the answer" which might be beneficial to other community members reading this thread. And, if you have any further query do let us know.
Joro 0 Reputation points

2023-10-31T02:46:18.5066667+00:00

@ChaitanyaNaykodi-MSFT Hi was there a resolution for this problem? I am having the same issue.

1 answer

ChaitanyaNaykodi-MSFT 26,101 Reputation points Microsoft Employee

2023-04-21T04:19:54.64+00:00

@Polka Oliver

Thank you for the response. Based on your observation above I think to resolve this issue we will require a support ticket as a support engineer can take a look at backend logs and determine the exact cause and help you with the DNS label transition. Meanwhile I will request you to keep the DNS label assigned in your old tenant, just in case if the label is unassigned and if it is taken by any other customer then it won't be recovered. Please follow the instruction from support engineer for further actions.

Please let me know if you do not have a support plan, I can help you with a one-time free support in this case. Thank you!
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ChaitanyaNaykodi-MSFT 26,101 Reputation points Microsoft Employee

2023-04-21T04:21:38.48+00:00

@Polka Oliver

If you do not have a support plan, could you please send an email to azcommunity@microsoft.com with the below details so that I can enable a one-time free support in this case.

Subject : Attn Chaitanya

Thread URL: Link to this thread.

Subscription ID

Please let me know once you have done the same.

Polka Oliver 5 Reputation points

2023-04-24T08:24:12.7+00:00

Hi, I've created the support request, should I mark this as answered or wait for the support team and post the findings here? @ChaitanyaNaykodi-MSFT

ChaitanyaNaykodi-MSFT 26,101 Reputation points Microsoft Employee

2023-04-24T23:42:53.3233333+00:00

@Polka Oliver Thank you for getting back. In such cases usually creating a support case is the way to move forward, but I would like to see the support case resolution first just in case. Will it be possible for you to email the support ticket number to azcommunity@microsoft.com? so that we can track the issue on our end. Thank you!
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Unable to re-use a DNS name label in a different tenant

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