Hello @Rafael Gil Sanchez ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
I understand that you would like to know how to redirect your root domain to a www domain that is in classic Azure Front Door.
To start with, you need to onboard your root or apex domain to Azure Front Door Classic following the below doc:
Mapping your apex or root domain to your Front Door profile basically requires CNAME flattening or DNS chasing. 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.
If you are using a different provider than Azure DNS, then you would need to contact the DNS provider and check if they support CNAME flattening or if there is any way to achieve this on their end. If it is not supported with your DNS provider, then maybe you could delegate your domain to Azure DNS and manage your DNS records in Azure DNS and here you will be able to create an Alias record which will help you onboard your apex domain to Azure Front Door.
Please refer: https://docs.microsoft.com/en-us/azure/dns/dns-domain-delegation
https://docs.microsoft.com/en-us/azure/dns/dns-delegate-domain-azure-dns
After you onboard your root domain to Azure Front Door Classic, you need to use a redirect rule and make rules engine configuration in order to redirect your root domain to www domain as below:
Refer: https://learn.microsoft.com/en-us/azure/frontdoor/front-door-url-redirect?pivots=front-door-classic
https://learn.microsoft.com/en-us/azure/frontdoor/front-door-tutorial-rules-engine
Kindly let us know if you need further assistance on this issue.
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