Azure frontdoor CName DNS Issue

DJ 0

I have an issue with a domain name registered external to Azure. I have setup two subdomains for the same domain name alongside the standard Azure domain created by default for Azure Frontdoor. We can then setup the routes against the subdomains to route through to our virtual network. This is straight forward to this point.

We update our DNS records to point to the Azure created domain name ending in azurefd.net for Azure Frontdoor. These being CName records. This is required by Azure for external domains managed outside of Azure. Thereafter the web browser tries to access the subdomains but fails. This scenario here is we have two subdomains of the same domain name both with CName records pointing to the same Azure created domain generated by Azure Frootdoor. Https requests fail to reach Azure Frontdoor. We did leave enough time for DNS records to propagate. I get the impression this scenario would only work if the domain name were registered directly with Azure.

This is the question we would like answered. Is there a fix that can be applied to Azure Frontdoor to allow external domains to be accepted using subdomains of that same domain in the routing using CName records held externally to Azure, allowing the use of only one instance of Azure Frootdoor for multiple subdomains?

KapilAnanth-MSFT 47,996 Reputation points Microsoft Employee

2024-07-02T04:57:10.0166667+00:00
@DJ ,

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

I am not aware of any such limitation.

After creating the CNAME Record, did you make sure you had Associated the custom domain with your Front Door for both the subdomains?

For Standard/Premium : Add a custom domain

The provisioning state of the custom domain should change to Provisioned. The validation state should change to Approved.

Pleases share a screenshot of the domains saying approved.

Can you please elaborate on what you mean by "web browser tries to access the subdomains but fails"

Do you get a timeout?

Or get a error message?

Cheers,

Kapil
Daniel noyn 1 Reputation point

2024-12-17T23:41:34.95+00:00

This is a chicken and egg issue they cannot update the front Door Custom Domain and have it full approved because Godaddy does not allow CNAME records with no IP address (and a second reason godaddy does not work also exists)
Go Daddy won't allow it, and if you try the trick that used to work to use a redirect, it will add two A records that cannot be deleted, and once that happens, then FrontDoor won't EVER resolve.

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Azure frontdoor CName DNS Issue

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