These are the steps for an Azure subscriber to expose an endpoint on Azure Front Door:

1. **Create an Azure Front Door Profile**: If you don't already have one, create an Azure Front Door Standard/Premium profile.

2. **Obtain a Custom Domain**: Purchase a custom domain from a domain provider or use an existing one. If your DNS domains are hosted on Azure, delegate the domain provider's DNS to Azure DNS.

3. **Create a CNAME DNS Record**: Create a CNAME record with your domain provider to point to the Front Door default frontend host. This maps your custom domain name to the Front Door default hostname.

4. **Map the Temporary afdverify Subdomain**: Map the temporary `afdverify` subdomain to verify domain ownership.

5. **Add the Custom Domain to Azure Front Door**: Go to the Domains pane of your Azure Front Door profile. Select "+ Add" to add a new domain.

6. **Validate the Custom Domain**: Choose the domain type (Non-Azure validated domain or Azure pre-validated domain). If it's a Non-Azure validated domain, manually enter the custom domain name.

7. **Associate the Custom Domain with Your Endpoint**: Associate the validated custom domain with your Azure Front Door endpoint.

8. **Verify the Custom Domain**: Ensure the custom domain is correctly associated and verify it through the Azure portal.

9. **Configure HTTPS (Optional)**: If you want to secure your custom domain with HTTPS, configure it by following the steps to enable HTTPS for your custom domain.

10. **Test the Configuration**: Test the setup by accessing your custom domain to ensure everything is working correctly.