Onboard a root or apex domain to Azure Front Door
Azure Front Door uses CNAME records to validate domain ownership for the onboarding of custom domains. Azure Front Door doesn't expose the frontend IP address associated with your Front Door profile. So you can't map your apex domain to an IP address if your intent is to onboard it to Azure Front Door.
The DNS protocol prevents the assignment of CNAME records at the zone apex. For example, if your domain is
contoso.com; you can create CNAME records for
somelabel.contoso.com; but you can't create CNAME for
contoso.com itself. This restriction presents a problem for application owners who have load-balanced applications behind Azure Front Door. Since using a Front Door profile requires creation of a CNAME record, it isn't possible to point at the Front Door profile from the zone apex.
This problem can be resolved by using alias records in Azure DNS. Unlike CNAME records, alias records are created at the zone apex. Application owners can use it to point their zone apex record to a Front Door profile that has public endpoints. Application owners point to the same Front Door profile that's used for any other domain within their DNS zone. For example,
www.contoso.com can point to the same Front Door profile.
Mapping your apex or root domain to your Front Door profile requires CNAME flattening or DNS chasing, which is where the DNS provider recursively resolves CNAME entries until it resolves an IP address. This functionality is supported by Azure DNS for Azure Front Door endpoints.
There are other DNS providers as well that support CNAME flattening or DNS chasing. However, Azure Front Door recommends using Azure DNS for its customers for hosting their domains.
You can use the Azure portal to onboard an apex domain on your Azure Front Door and enable HTTPS on it by associating it with a TLS certificate. Apex domains are also referred as root or naked domains.
Apex domains are at the root of a DNS zone and don't contain subdomains. For example,
contoso.com is an apex domain. Azure Front Door supports adding apex domains when you use Azure DNS. For more information about apex domains, see Domains in Azure Front Door.
You can use the Azure portal to onboard an apex domain on your Azure Front Door profile, and you can enable HTTPS on it by associating it with a TLS certificate.
Onboard the custom domain to your Azure Front Door profile
Select Domains from under Settings on the left side pane for your Azure Front Door profile and then select + Add to add a new custom domain.
On Add a domain page, you'll enter information about the custom domain. You can choose Azure-managed DNS (recommended) or you can choose to use your DNS provider.
Azure-managed DNS - select an existing DNS zone and for Custom domain, select Add new. Select APEX domain from the pop-up and then select OK to save.
Another DNS provider - make sure the DNS provider supports CNAME flattening and follow the steps for adding a custom domain.
Select the Pending validation state. A new page will appear with DNS TXT record information needed to validate the custom domain. The TXT record is in the form of
Azure DNS-based zone - select the Add button and a new TXT record with the displayed record value will be created in the Azure DNS zone.
If you're using another DNS provider, manually create a new TXT record of name
_dnsauth.<your_subdomain>with the record value as shown on the page.
Close the Validate the custom domain page and return to the Domains page for the Front Door profile. You should see the Validation state change from Pending to Approved. If not, wait up to 10 minutes for changes to reflect. If your validation doesn't get approved, make sure your TXT record is correct and name servers are configured correctly if you're using Azure DNS.
Select Unassociated from the Endpoint association column, to add the new custom domain to an endpoint.
On the Associate endpoint and route page, select the Endpoint and Route you would like to associate the domain to. Then select Associate to complete this step.
Under the DNS state column, select the CNAME record is currently not detected to add the alias record to DNS provider.
Azure DNS - select the Add button on the page.
A DNS provider that supports CNAME flattening - you must manually enter the alias record name.
Once the alias record gets created and the custom domain is associated to the Azure Front Door endpoint, traffic will start flowing.
- The DNS state column is used for CNAME mapping check. Since an apex domain doesn’t support a CNAME record, the DNS state will show 'CNAME record is currently not detected' even after you add the alias record to the DNS provider.
- When placing service like an Azure Web App behind Azure Front Door, you need to configure with the web app with the same domain name as the root domain in Front Door. You also need to configure the backend host header with that domain name to prevent a redirect loop.
- Apex domains don't have CNAME records pointing to the Azure Front Door profile, therefore managed certificate autorotation will always fail unless domain validation is completed between rotations.
Enable HTTPS on your custom domain
Follow the guidance for configuring HTTPS for your custom domain to enable HTTPS for your apex domain.
Create an alias record for zone apex
Open Azure DNS configuration for the domain to be onboarded.
Create or edit the record for zone apex.
Select the record type as A record and then select Yes for Alias record set. Alias type should be set to Azure resource.
Select the Azure subscription where your Front Door profile gets hosted. Then select the Front Door resource from the Azure resource dropdown.
Select OK to submit your changes.
The above step will create a zone apex record pointing to your Front Door resource and also a CNAME record mapping 'afdverify' (example -
afdverify.contosonews.com) to that will be used for onboarding the domain on your Front Door profile.
Onboard the custom domain on your Front Door
On the Front Door designer tab, select on '+' icon on the Frontend hosts section to add a new custom domain.
Enter the root or apex domain name in the custom host name field, example
Once the CNAME mapping from the domain to your Front Door is validated, select on Add to add the custom domain.
Select Save to submit the changes.
Enable HTTPS on your custom domain
Select the custom domain that was added and under the section Custom domain HTTPS, change the status to Enabled.
Select the Certificate management type to 'Use my own certificate'.
Front Door managed certificate management type is not currently supported for apex or root domains. The only option available for enabling HTTPS on an apex or root domain for Front Door is using your own custom TLS/SSL certificate hosted on Azure Key Vault.
Ensure that you have setup the right permissions for Front Door to access your key Vault as noted in the UI, before proceeding to the next step.
Choose a Key Vault account from your current subscription and then select the appropriate Secret and Secret version to map to the right certificate.
Select Update to save the selection and then Select Save.
Select Refresh after a couple of minutes and then select the custom domain again to see the progress of certificate provisioning.
Ensure that you have created appropriate routing rules for your apex domain or added the domain to existing routing rules.